What are those things in the title? Brake fluid is categorized as one of those three ratings. Most brake fluid that comes in a new car will be rated DOT 3. A few will Use DOT 4, and very few will ever use DOT 5 which is a silicone based product.
If you want to look at brake fluids from a chemical standpoint DOT 3 fluids are based on glycol and glycol esters. DOT 4 fluids are much like DOT 3 fluids, but also contain borate esters. There is another rating called DOT 5.1 that consists of borate esters.
Let’s look at what brake fluid’s (and clutch fluid) real job is. Brake fluid is used to transmit pressure from the brake pedal to the extreme ends where the disk brake calipers or drum brake cylinders are. This pressure is then applied to the pads (or shoes) against the rotation of the brake rotor (or drum). It is this property not to compress that allows it to do its job well.
Back to the chemistry. Notice that water is not listed as a component of brake fluid. Water boils (sea level air pressure) at 212 degrees F (100 C). Since the disk rotor can and will generate over 1000 degrees (F) of heat and transfer 400 degrees or more to the caliper water is not a good fluid to choose.
Why do I mention water? The chemistry of DOT3 and DOT 4 brake fluids attract water. Right out of the air. In fact the anti-freeze you use is probably glycol based just because it mixes well with water.
The difference between the DOT (Department of Transportaion) ratings of brake fluid are the boiling point ranges that they achieve both dry (no water absorbed) and wet (about 3-4% water content). For DOT 3 the dry boiling point is at least 401 and the wet 284 degrees. DOT 4 raises the bar to 446 and 311 respectively. Those are the DOT ratings mind you , and there are high performance brake fluids that exceed those ratings.
The cost of brake fluid can vary as well from less than $0.20 an ounce to over $2.00 an ounce. Some of the high performance fluids are rated well over 500 (to almost 600) degrees boiling point dry. Wet boiling points will also vary, but be well over 400 degrees.
The higher boiling points are critical to those of you that wish to spend time on a race track. Once you boil your brake fluid it will not recover and you MUST bleed and change out the fluid.
The every day driver will find brake performance just fine by sticking with the fluid that the dealership recommends unless they use their vehicle to the extreme, such as a newspaper delivery route or negotiating their way down curvy mountain roads. You will know because the brake pedal will start to feel mushy as the fluid overheats and the pedal may even go to the floor.
So what is the big deal? The big deal is that most of us never flush and replace our brake fluid. In fact, if you go to a garage and have a “brake job” done it is highly unlikely that they will do much more than bleed the brake lines. This means that the old – water soaked – tired – brake fluid will still be there. The water can react to oxidize brake components from the inside out. What you should do, probably once a year, is have the old fluid flushed and completely replaced with fresh brake fluid.
Bleeding Methods
If your mechanic does it the right way they will use a vacuum bleeding system. The first thing they will do is remove all the wheels so they can get to the brake bleed screws. Then they will vacuum out the brake fluid reservoir of old fluid. Then the technician will ensure that new fluid is always kept in the brake fluid reservoir and pull it through the system starting at the brake bleeder farthest from the master cylinder. Vacuum bleeding is preferred since pressure bleeding actually introduces and dissolves air into the new fluid. This will gas out as the new fluid is heated and the pedal will get spongy again.
If you do your own brake bleeding and don’t have access to a vacuum bleeder you can take longer and bleed it in the traditional fashion of using the brake pedal to push out fluid and air. The approach is similar. Loosen the lug nuts, get the car up in the air on jack stands (if you DON’T know how to do this safely, DON’T do it yourself), and take off all the wheels. Prepare yourself with some clear tubing and catch cans for the old fluid. I take used pint sized plastic milk containers and suspend them with bent coat hanger from the caliper or brake drum. The milk containers are nice because you can use the hollow handle to push the tubing into where it will be held on one end while the other end will go over the bleeder screw (valve). Use a box end wrench of the appropriate size to open and close the bleeder screw. You will need someone who follows directions well to sit in the car and use the brake pedal. Don’t let them take their foot off the brake pedal unless the valve is closed.
The goal will be to get the new fluid all the way to the farthest points in the system so the rear brakes will take the longest to flush. A company called Ate makes a blue colored fluid that makes it easy to tell that you have accomplished that.
Unless your factory manual specifies something different you start with the right (passenger side) rear, then move to the left (drivers side) rear, then the right front, and finally the left front. If you have ABS you may need to either leave the engine running or short out a test connector to ensure the ABS pump cycles while bleeding. This last part (ABS) will depend on you doing research on YOUR particular vehicle.
As you cycle from each corner you will have to work in concert with your buddy at the brake pedal. The goal is not to get any air introduced into the system while you bleed it. To prevent air from entering you need to keep the reservoir from going empty. So check it often and add new fluid as needed.
You should also remove as much of the old fluid from the reservoir before you add new fluid to the reservior. A turkey baster or similar device will allow you to do that. Just have spray “brake clean” ready in case any fluid get on painted surfaces. If left on paint it will remove it. PROTECT YOUR EYES.
The routine for bleeding as a team goes like this. The person in the car on the brake pedal needs to pay attention to your instructions so that they won’t lift their foot off the pedal if you have the bleeder still open. The first thing you will ask them to do it pump the brake pedal about three times. This is to ensure that some pressure is in the line so that fluid (and any air, water, etc.) will come out of the bleeder when you open it. They shouldn’t pump the pedal like they are making a panic stop. Just a nice easy stroke will do the job. They don’t have to keep an enormous amount of pressure on the pedal either. Just enough to move it toward the floor is fine.
After they have pumped the pedal, they should let you know that they are “holding” pressure on the pedal. You should be at the bleeder screw with a wrench on it and a tube going to the catch bottle. You open the valve and close the valve and then let the person on the brake pedal know that they can lift their foot. If the foot comes off the pedal while the valve screw is open you will introduce air into the line – that is not your objective.
There is a product call Speed Bleeders that can be a huge help. It is a bleeder screw with a spring loaded check valve that prevents air from getting back into the system. I’ve seen them sold in auto parts stores, but I know that they are also available on line.
You will need to continue this until you get nice, clean, new fluid out to the particular brake you are working on and then repeat for the other three. Be sure to keep enough fluid in the reservoir to prevent air from entering the system from that end.
You CAN do this yourself if you take your time, get prepared prior to starting, and have someone who knows what they are doing to help you. Otherwise – find a professional that knows what they are doing.
Brake fluids gain contamination as they age and should be replace periodically. If you race you should change your brake fluid as often as you change your oil.
January 9, 2007 at 5:27 pm |
Jim,
Very complete coverage of the topic. I recognize that can in the first pic, I believe it’s what you introduced me to in the corvette. With traffic as it is, and my reckless youth more fully in the rear view mirror these days, I haven’t boiled the fluid, nor warped a rotor in a very long time. However, having done both several times, your advice is really spot on. So many of us, especially in younger days concentrated on the engine, and did little for our breaks except pads.
Are there any extra proceedures for cars with antilock brakes? Especially the first generations? Do we need to do something to cycle the antilock pump to get any stored old fluid out during the flushing proceedure?
January 9, 2007 at 8:35 pm |
I don’t know how kosher it is but a technique I’ve used with ABS is (while the car is up on a lift) to put the car in gear and rev up the engine and then put on the brakes. That engages the ABS because it reads it as if the wheels have locked up. Of course I did this on an all wheel drive (AWD) car and maybe that makes a difference as well.
Some motorcycles with ABS have a pin you can short out that will cycle the ABS pump and I heard that some fo the Bosch ABS systems have diagnostic mode that does pretty much the same thing.
You can always just bolt up everything and go out and drive where you can engage ABS safely and then come back and put it up in the air and bleed again.
I think the vacuum method of pulling the fluid to the bleeder screw should do a pretty good job.
January 21, 2007 at 2:24 pm |
Hello Jim:
Thanks for your timely comments on brakes. As an old-timer mechanical type who still likes things done right (ie, DIY), but whose knees and hips are betraying him, I am disappointed that my just-completed brake job (pads, rotors, shoes, bleeding) has not corrected spongy brake pressure on my 2000 Pontiac Montana with ABS. I guess I have to get back on those knees and pull ALL of the fluid out of the system (I did not get a bubble out when I pump-bled each brake about 8-10 strokes, after replacing the parts). Better this than assuming the culprit is a bad master cyclinder, I suppose.
Any other possibilities?
Many thanks,
Harold Wilson,
Rockwood, Ontario, Canada
January 21, 2007 at 2:25 pm |
One more question… any problem mixing Dot 3 & Dot 4 brake fluids?
January 21, 2007 at 3:46 pm |
ABS can make a brake job can be a little tricky. You may need to find out if GM (Pontiac) has a special procedure to get the ABS ump active while bleeding the brakes.
But try a couple of things for me. Get in the car and start it up and put pressure on the brake pedal. If you continue to apply pressure does the pedal slowly move toward the floor? If the answer is yes that indicates that the system is not a closed system as it should be. So if you’ve removed anything like a brake line or a caliper or a wheel cylinder you need to make certain that the brake line fittings are tight.
Some vans and pickup trucks also have a load sensing proportioning and by-pass valve. On vehicles so equipped it is mounted to the body or frame and connected to the rear axle. It is also connected to the brake lines because it is there to control the amount of pressure that goes to the rear part of the brake system. Its function is to react to changes in loads on the rear of the vehicle. If it has worn or been contaminated with water in the brake system it can leak and make it impossible to get a firm pedal until it is replaced.
I don’t know enough about you Pontiac to know if it has this kind of valve or not.
I do know that GM has produced several models like the GMC Jimmy, Chevy S10 and they all seem to have the characteristic of a spongy pedal right from the factory. It seems strange that the corporation that can produce the Corvette feels that their standard vehicles should have mushy pedal feel.
Mixing DOT 3 with DOT 4? Not a good idea. They have different chemistry. In later cars you can probably get away with it, but older cars should stay with DOT 3 unless all the components are updated.
If this is the first time the brake fluid has been flushed and bled you may be correct in looking to the master cylinder as the culprit
Let me know how it goes.
January 24, 2007 at 5:19 pm |
Well My dirtbike says use dot 4 break fluid only
And I was wondering would dot 3 work If i absalutly had to use it
Like if i only needed it for an hour or so then change it??
January 24, 2007 at 6:11 pm |
OK – if you ABSOLUTELY HAVE to use it you can get away with DOT3, but I would avoid it if at all possible. Remember that the chemestry of the two are very different and one of the reasons the factory says use DOT 4 only is that DOT 3 may not be compatible with inner seals. If you use it for just an hour you really need to flush it out COMPLETELY with DOT 4.
April 11, 2007 at 10:18 pm |
Have a 1991 Toyota with ABS (Bosch/Denso) that I replaced the master cylinder on. When I bled the brakes I could not get more than a couple of drops of fluid out of the left rear and right front wheel cylinders. The right rear and left front bled normally. There are no bleeders on the ABS module.
Any suggestions.
April 12, 2007 at 6:38 am |
Did you “bench bleed” the master cylinder prior to mounting it? That is where you set the master cylinder on a bench and with tubes going from the outlets back to the reservoir and manually pump fluid through the master cylinder. This gets air out of the new part and makes sure that you don’t pump a big bubble of air into your brake lines the first time you bleed the system as a whole.
If you didn’t, you can still fix things. First take off the master cylinder and bench bleed it. You will still have air in your system, but I believe you can get rid of it.
There are a couple of ways to bleed the system now. Fortunately these early ABS systems are not usually as complex as the newer ones are so there is a good chance that normal bleeding techniques will get the job done.
There is the two person method (unless you have Speed Bleeders) where one person operates the pedal and another opens and shuts the bleeders, but it sounds like you know this already.
There is also gravity bleeding where you put hoses and containers on all the bleeders and then, keeping the master cylinder reservoir filled, open all the bleeders and let gravity slowly push fluid to the extremes.
Vacuum bleeding might also be an option for you, but I think you will be fine with the method you have been using.
As far as the ABS goes you can try leaving the engine running as you bleed the system. With the car safely up in the air you can always put it in gear and then hit the brakes. The ABS system will read that as the brakes locking up and will pump the ABS pump. Be careful when you do this and be certain that the car is secure. If you have any doubts – DON”T use this technique.
Good luck and let us know what happens.
April 16, 2007 at 7:11 pm |
I have a question about my motorcycle. I purchsed it used and the owner manual says use dot 3 or dot 4 brake and hydrilic fluid. I really do not care to mix the two and I am wondering if there is a way to tell what is in my system.
If worse comes to worse, in my situation, is there a problem mixing the two with out completely flushing the system
April 17, 2007 at 5:48 am |
Jeff -
The big concern with the type of brake fluid is its compatability with the flexible components of the brake system. Typically refered to as the “rubber” parts. They are not usually made of rubber but some will coexist well with DOT 3 and then start to fall apart with DOT 4 because of the difference in chemestry between the two fluids. If the owners manual says you can use either DOT 3 or DOT 4 then the manufacturer has taken into account the differences in chemical make up and the “rubber” parts won’t deteriorate because of the difference. So you could go along quite happiliy with a mix of DOT 3 and DOT4.
In order to tell which is in you system presently it would take some chemical analysis that you would best to go to a lab to have done.
You want to flush your brake fluid once a year in any case. So it might be more cost effective to just go ahead and put in your choice and completely replace what is in the system now. Any residual not flushed will not harm your brake systems components.
June 15, 2007 at 12:16 pm |
(i dont know perfectly english)
i have an 2000 mitsubishi galant, i cheked the brake fluid container, and it was to the minimum line, i dont know what type it was, if dot3 or dot4, i went to the autozone and i buy a dot 4 , and i fill with this… my question if there will be any problem by mixing dot3 with dot 4.
in top of the container says i can fill with dot3 or dot4.
June 15, 2007 at 8:53 pm |
Edwin you are in luck since the Mitsubishi brake systems can tollerate both DOT 3 and DOT 4 brake fluids. So no problem there. Mixing the two fluids should not cause any problem either.
What you should consider though, is why is the fluid low? Typically the fluid gets lowwer as the pads wear so you should pull the wheels and check the thickness of the brake pads soon. Many brake systems use the fact that the fluid level drops to turn on a warning light. This, along with noise makers on some pads, will tell you that your pads have warn to the point that they should be replaced.
When you change your pads (and or rotors) be sure to replace all the brake fluid with fresh stuff.
June 17, 2007 at 12:38 am |
thanks so very much i will check the pads soon.
July 13, 2007 at 1:28 am |
Jim, My 94 dodge Viper calls for DOT3 Brake Fluid. can i use Dot 4?
July 13, 2007 at 7:12 am |
Mitchell -
When DOT 3 is specified over DOT 4 it usually means that there could be incompatibility between the chemistry of the seals of the brake system and DOT 4 fluid. If you are looking for better performance you might want to see if any TSB’s (technical service bulletins) have come out from the factory on brake fluid for your Viper that would allow you to use a DOT 4 fluid.
A dealership should have the latest information on that. http://www.alldata.com can be a help there.
You can also check with a DOT 4 brake fluid manufacturer and see if they have something compatable with a DOT 3 system.
Jim
October 21, 2007 at 3:29 pm |
Jim, I have a 1969 Peugeot 404 Sedan and was at a recent import show when the topic of Dot 3 vs. Dot 5 came up. I need a second opinion. Since I don’t have ABS brakes on that car, I was told that the Dot 3 tends to damage the rubber seals in the wheel cylinders and if the car sits for a period of time the brakes can lock up or stick. The Dot 5, due to the silicone base, helps keep the old rubber parts in better shape. Any thoughts on that? Thanks for your help.
October 21, 2007 at 6:06 pm |
Rob -
If you drive the Peugeot from time to time and change and flush the brake fluid once a year you should have no problems. The 404’s brake system components were designed to be compatible with DOT 3. If you were to switch to a DOT 5 brake fluid you would have to replace all the components in the brake system. I have seen situations where people have tried to flush the brake system instead and the results have not been good. If you REALLY want to try a synthetic brake fluid then try a DOT 5.1. Motul makes a DOT 5.1. That way you won’t have to change out everything.
Are you storing your car for long periods, say 3-6 months? In that case a DOT 3 or 4 fluid will suck moisture out of the air, but since the fluid is not being disturbed by use the amount should be minimal and contained in the reservoir.
If this is a street driven car then you should be fine with yearly flush of the system. If you put this car on a road racing track you should flush the system as part of the normal preparation in any case.
Hope this information helps.
Jim
November 9, 2007 at 10:52 pm |
Jim
I am rebuilding an E type Jag from the ground up. Have had the brake system totally overhauled (stainless steel sleeved the calipers, new brake lines etc) It will be a weekend driver. What do you recommend as a brake fluid? If I use Dot5 what is the cleaning fluid you can use with it that is compatable?
November 10, 2007 at 7:44 am |
Geoff -
It sounds like a great car. I am so jealous. I don’t recommend the DOT 5 brake fluid as I have found it is more trouble than it is worth. It can be a bit more compressible than DOT 3 or 4 as well, and I don’t think you will require the high heat capabilities.
It is great that you have been able to sleeve the calipers as that was a weak spot. You really should be fine with a good quality DOT 4 fluid. I would just change it out once a year.
Enjoy this classic. I would love to see the photos of the finished project.
Jim
November 23, 2007 at 9:51 am |
I am restoring a 1962 Triumph TR4, and trying to determine whether it currently has DOT 5 brake fluid in the system. I’ve taken some DOT 4 and added some of the fluid from the car to see if they will mix, but the results are not conclusive. I don’t want to add the wrong fluid. How do I tell? The only other option is to replace everything in the brake system and start with new fluid.
November 23, 2007 at 4:07 pm |
DOT 5 is a silicoln based fluid and will not remove paint. So if you can take an eye dropper full of the fluid and put it on something that you don’t mind having the paint ruined on that should let you know in an hour or two if it is DOT 5 or not. If it disolves paint then it is DOT 3 or 4.
January 6, 2008 at 10:44 pm |
I have a H3 Golf Car. The cap on the brake fluid says to use ONLY Dot 4 fluid. The mechanic had to install a new brake line and drained and refilled with Dot 3. When I asked him why he didn’t use Dot 4, he said it didn’t matter.
When it states to only use Dot 4, will it matter? When I need to add fluid, can you mix 3 and 4? And yes, Jim you are right about it disolving paint.
January 7, 2008 at 7:15 am |
Robin -
You can “probably” get away with using DOT 3, but I would be concerned that the manufacturer said DOT 4 ONLY for a reason. Usually this is because of compatibility with some of the seals and cups in the brake system. You CAN mix DOT 3 and DOT 4, but of course the ideal would be to stick to one and make sure it is the right one.
I am surprised that it needed a new brake line so soon. I hope it was a warranty item.
I would recommend changing to DOT 4 ASAP.
Jim
February 14, 2008 at 12:58 pm |
Jim, you have a great site here. I’m still not clear on the 3, 4, and 5’s. I have a 2000 Dodge Durango and tow with a free wheeling tow-dolly (no brakes) Dodge recommends ‘DOT 3′. Should I move UP to a 4 or even a 5 ? Thanks for the tip on ‘bleeders’ and thanks ahead of time four your response. Tucky
February 14, 2008 at 5:32 pm |
First of all, have you experienced any problems so far? Rule of thumb is – if it isn’t a problem, don’t fix it.
Dodge insists on a DOT 3 for that truck’s brake system. Now I haven’t talked with a Dodge engineer, but I can only surmise that they are concerned about the fluid’s compatibility with seals and other parts of the system. If those parts of the system are designed for DOT 3 then there is a very real possibility that DOT 4’s chemistry would not be compatible.
I have seen cases where a DOT 3 system has been switched to a fluid that claimed to be compatible with both DOT 3 and DOT 4 and then small black particulates started showing up in the fluid after the braking system was subjected to high heat loads.
Stick with a high quality DOT 3 is my advice.
February 24, 2008 at 2:10 pm |
Great info, Jim. Thanks. 2 inside lower seized pistons on a 2003 4Runner today and will be replacing both calipers and flushing the system using your technique. Thanks again. Chris
April 19, 2008 at 12:12 pm |
hi Jim
I’ve a Toyata Camry, 2L, SV21,1992 which states that DOT 3 only be used. The brake shop mechanic told me it’s OK to use the Castrol Response Dot 4 with the front label which states it’s a DOT 4 and DOT 3 fluid. I’m not sure if I should use a straight Castrol DOT 3 instead.
Thanks for your attention
John hon
21/04/08
April 19, 2008 at 1:08 pm |
In the US I would recommend Castrol GT LMS brake fluid if you need to mix fluids. Although I would recommend you replace all the fluid.
http://www.castrol.com/castrol/liveassets/bp_internet/castrol/castrol_usa/STAGING/local_assets/downloads/p,q/pds_GTLMABrakeFluid.pdf
Castrol states that Castrol Response DOT4 “Advanced braking performance for every day driving. Castrol Response Dot 4 is recommended for use in all cars, motorcycles and light commercial vehicles operating under normal driving conditions where either a DOT 3 or DOT 4 product is required. It is suitable for both disc and drum brakes, including modern vehicles fitted with ABS. ” To me this says that Castrol has a product that will work just fine in your DOT3 system.
Castrol Response is not marketed as such in the US so I didn’t recognize it at first.
April 23, 2008 at 4:40 pm |
I have a 06 gsxr 1000 and not knowing my pap put dot 3 in it when it calls for dot 4. The first ride after he changed it my front brakes locked up tight when I was going about 50 mph, I didnt wreck but I had to bleed the brake line before I could move it. Could the dot 3 caused that or was it something else.
April 23, 2008 at 7:38 pm |
When you say he put in DOT 3 did he just add the fluid to the system or did he bleed the system? If he added it to the system then, it sounds like a true compatability problem. If he bled the system he might have gotten dirt or contamination where it caused the problem. Stick with the factory recommended fluid.
May 26, 2008 at 12:08 pm |
I have a 2001 Alero (DOT 3) and I just added DOT 4 brake fluid which on the can says can be used in all DOT 3 and DOT 4 vehicles. Now it feels like the brakes are locked up and the car won’t move. What can I do? What is going on? Thanks.
May 26, 2008 at 12:37 pm |
In this case I don’t think I would jump to blaming the brake fluid. First check to see if someone might have set the parking brake. It happens.
The next step would be to get it to someone (technician) that has a scan tool to check the control components. The Alero has an EBCM – electronic brake control module, BCM – body control module, and the IPC – instrument panel cluster itself. The technician can check for trouble codes.
If it is not the parking brake this sounds serious. Nothing I would want to try to diagnose through this blog. Have a qualified technician check it out please.
June 18, 2008 at 1:43 pm |
Jim, I need your help. As a father’s day gift, I took my husbands car for an oil change, washed and it topped off his brake fluid (jiffy lube said it was low). So my naive self stood in Pep Boys and figured I’d buy the most expensive one, figuring it was a better brand. Only after I put in 3 tablespoons of this new fluid did I wipe off enough grime to read the brake fluid cover says “DOT THREE ONLY”. And what did I put in? Dot 5. Reading the above comments, it sounds like I didn’t do him much of a favor. What is your advice for me? It’s a 98 Rav4 and I’m not looking to be a widow.
June 18, 2008 at 5:45 pm |
Three table spoons full isn’t too bad. One reason the brake fluid was probably low in the first place is that as the brake pads wear down the fluid level drops. If all it took was three tablespoons then the brakes should be OK as far as wear goes. If it is way down it may be time to replace the pads in any case.
So the two brake fluids are not compatable, but it should not lead to brake failure. Try to find a place (not Jiffy Lube please) and have the brake fluid replaced. A good shop should be able to suck all the old fluid out of the reservoir and then vacuum out the old fluid at each wheel’s bleeder valve as new DOT 3 is added to the reservoir.
That was a very thoughtful Father’s Day gift in any case.
June 18, 2008 at 10:37 pm |
Your advice is wonderful thanks! My neighbor told me that it was possible that the seals could wear out and the brakes might suddenly stop working!
Jiffy Lube actually refuses to touch brake fluid or fill it. I had to beg them to just check the level. Thank you Jim! Glad to know I have a couple of weeks before I have to deal with this. I was told a good clean out of brake fluid is about $200 due to labor.
June 28, 2008 at 7:44 pm |
Jim, I have a 1995 Nissan 240sx that is built up and has a turbo on it. I’m currently using a Centerforce dual friction clutch. I’m using Dot 3 fluild for the clutch. After it has been driven for a short time the pedal seems to feel softer then when I first put the fluid in and the fluid turns a brown color. Is the additional heat from the turbo causing the fluid to breakdown early? Can I run DOT 4 fluid for the clutch or will this have an adverse effect on any seals?
June 29, 2008 at 5:52 am |
Rod -
The soft pedal indicates that there is a leak in the system somewhere. The fluid getting darker indicate that the master and/or slave cylinder is worn out.
I would consider replacement of the clutch slave cylinder as well as the master cylinder at this time. It sounds like they are at the end of their useful life.
The DOT 3 fluid should be fine even with the hotter engine compartment temperatures that the turbo is creating.
There are aftermarket stainless steel braided lines for hydraulic clutches that replace the stock flexible hose, if you have one. This might be a good time to replace that flexible hose as well.
I’ll bet you are enjoying that 240SX. They are a great rear wheel drive car that is very responsive to modifications.
Jim
August 28, 2008 at 7:21 pm |
I have always wondered about how brake fluid gets contaminated by atmospheric moisture when its in a sealed system. I once read that the air (and the moisture in the air) is able to actually go through rubber brake lines (which seems terribly odd since clearly brake fluid can’t go through the other direction and at times the brake fluid is put under tremendous pressure). If true, it makes me wonder if switching to “stainless steel braided lines” (actually Teflon with braided stainless steel over it) might make brake fluid resist contamination longer.
I also had a conversation with someone at Valvoline who claimed that their DOT4 fluid has special additives to ensure compatibility with DOT3 only braking systems. It makes me wonder if any manufacturer would risk putting out a glycol-based fluid that isn’t compatible with all glycol-based braking systems.
August 28, 2008 at 9:05 pm |
Dan -
Thanks for the comments. I personally have not been impressed with Valvoline and their brake fluid product. When I tried it out for some track use on a previous car I found it did not stand up to the heat and ended up with some black deposits floating around in the fluid. I sent a sample to Valvoline and was told that it was fine. No more detail than that. Nothing to back up their claim that the fluid was fine even though I knew it had been over heated.
If the cap says DOT 3 I stick with DOT 3.
Jim
October 1, 2008 at 12:37 pm |
My base fluid is DOT5 it just needs topping up, not by a lot. Can I use DOT4 ?
All the garages I’ve been to only have DOT4 and trust me it’s a long way for DOT5.
I’d appreciate your advice.
Thanks
Bob
October 1, 2008 at 1:26 pm |
NO! You cannot mix a DOT 5 with anything else. It is not compatable with anything else.
October 5, 2008 at 12:25 pm |
Do not use brake cleaner around paint! Use a damp rag or paint care cleaner instead.
January 2, 2009 at 8:57 am |
hi, i have an old 86 nissan bluebird wagon that uses dot 3 . but here in portugal is very difficult to find this fluid. my question is can i mix dot 4 or do i have to fluch the system first? or can i only use dot 3??
thanks
January 2, 2009 at 6:16 pm |
Cesar -
Sounds like a tough one. The Nissan really should be kept with DOT3. Switching to DOT 4 would likely lead to deterioraion of the seals. But, if you were willing to change out the master cylinder and maybe the calipers and wheel cylinders with new ones the material used in those seals would likely be more modern and less likely to be affected in a bad way by DOT 4 brake fluid. I would not mix the two types of fluid. I would flush the system as best you can.
If you can find a garage that uses a vacuum bleeder that would be best. Otherwise gravity bleed by opening up all the bleeders and taking the cap off the master cylinder. Be sure to use hoses and catch containers so you don’t get the fluid all over.
I hope this helps.
Jim
January 31, 2009 at 5:59 pm |
Jim, I’ll have to disagree with you about Valvoline. I’ve road raced a Viper for 7 years, and I’ve gone the Motul and Castrol SRF route, and these days I just run Valvoline DOT 3/4 and it’s just fine for track days. I run large AP Racing calipers and typically peak around 160 MPH at my fastest track days and haven’t ever experienced any boiling issues. Just my two cents. (I ended up here because I’ve been considering a pressure bleeder. Good to see somebody helping people out like this.)
February 1, 2009 at 1:55 pm |
Mac -
I’m glad your experience with Valvoline brake fluid was better than mine. It my have been the difference in the make up of the seals in my calipers.
Vacuum bleeding is the way to go in my book and Speed Bleeders take a close seond.
Jim
March 27, 2009 at 2:16 pm |
Greetings: I am considering changing the brake fluid in my 08 Toyota Yaris to the SL.6 low viscosity product made by ATE. The main reason for this is to see if it will enhance my cold weather hydraulic clutch function, as it is noticeably harder to operate on the colder winter mornings.
I assumed it would also be an upgrade for my ABS as they recommend it for these systems. Toyota though specifies Dot 3 fluid be used in the clutch and brakes which in my case share the master cylinder, but does not specifically state not to use any other fluid. Would there be any downside to doing this change over?
Thanks
March 27, 2009 at 5:29 pm |
The SL6 version of Ate is new to North America. I don’t have any direct experience with it, but the write up on the Ate site certainly sounds like it would be just what you are looking for. I would suggest contacting Ate directly about any compatability concerns with its use in a DOT3 system. Ate does say that it meets or exceeds DOT3 requirements, but does not address compatability.
You can email them at:
ate-customerservice@continental-corporation.com
April 3, 2009 at 8:05 am |
Thanks for the help Jim. Here is the reply I received from ATE customer service verbatim.
Hello: I had forwarded to your question to my Quality Assurance Manager, his
response:
“SL6 may be used in vehicle higher than Model Year 1990 with ABS. It
should not be mixed with DOT3 or used as “add on”. Thx.”
Please let me know if you need further assistance.
Thank you for choosing ATE!
April”
They didn’t specifically use the word compatibility in their response and I used the term in reference to Toyota vehicles in my question to them, so I guess this is a go then!
Thanks again.
April 27, 2009 at 9:41 pm |
Hi Jim
I have a Honda CBR250RR and it says to use DOT 4 brake fluid. I used DOT 3 to top up because I didn’t know [any better]. So far I haven’t had any problems. After reading this thought I should use DOT 4 and planing to flush all DOT 3 and 4 mix and to fill with DOT 4. Will it harm the inner seals and washers?
Thank you
April 28, 2009 at 5:49 am |
Chinthaka -
Sounds like a good plan to me. You will probably get away without any damage as DOT 4 is more tolerant of DOT 3 in the mix than DOT 3 is of DOT 4 chemestry.
Jim
May 18, 2009 at 9:24 pm |
Hello Jim,
My wife’s 1981 Volvo 245 DL/B21F 4 cyl.engine with 81,457 original miles developed spongy brakes. Local gas station mechanic flushed the DOT-4 fluid out of the car and replaced it with DOT-5. Although there was very small improvement in the brake feel, mechanic assured my wife that this was much better fluid for the car. In one years time the pedal became progressively worse. Black film now coates master cylinder reservoir wall, and the pedal goes down half-way. I decided to replace master cylinder, all wheel calipers and brake hose. Please let me know the best way to flush (get rid of)the DOT-5 fluid to give brakes that hard feel they once had.
Thank you kindly for your help
Dan H.
May 19, 2009 at 5:33 am |
Dan H. -
I’m sure the mechanic’s heart was in the right place, but, as you found out, DOT 5 was not the way to go.
You have done the right (and expensive) thing in replacing the major components with new. Now the only DOT 5 is that left clinging to the metal lines.
While you have all the major stuff off the car (master cylinder, calipers, flexible hoses, etc. get some compressed air and blow the lines clear. DON’T DO THIS IF YOU HAVE ABS!
Then bench bleed the master cylinder and install it with the reservoir. Then add the flexible hoses, calipers, etc. and fill the master cylinder with fresh DOT 4.
I will assume that you have access to an air compressor because you need to use a vacuum bleeder for the next step. Not a hand vacuum bleeder, but one like the mityvac in the link above.
Start with the caliper on the front driver’s side of the car. I know, this is not the order that most cars do, but this is a Volvo. Vacuum through a good amount of fluid and keep the reservoir from going too low of fluid. Next do the same for the passenger front, then the driver’s rear, and finally the passenger rear caliper. Use plenty of fluid.
The front bleed screws take an 11mm wrench and the rears take an 8mm wrench.
When you are all done be sure to gently pump the brake pedal until it feels firm again. This should only take a half a dozen pumps. When it firms up hold the pedal firmly with your leg and feel if the pedal slowly moves toward the floor. If that happens go around to all the connectors with the proper wrench and make them tighter. You should get to the point where you pedal feels firm and doesn’t sink to the floor.
When you start the car the pedal will move toward the floor, that is normal with a brake booster system. do all your pedal testing with the engine off.
It is a lot of work, but should restore your brake system and make your Volvo safe to drive again.
Jim
May 19, 2009 at 7:55 am |
Hello Jim,
Thanks for the help and procedure. Although I have air compressor, I do not have vacuum device as you described. Could repeated use of compressed air through the system achieve similar result of evacuating DOT-5 from metal lines, -OR- should I after all the steps described by you are done, drive to a local shop with vacuum equipment and repeat the flushing by suction. One more thing; this Volvo has a pressure warning valve for the 2 hydraulic brake circuits and I was wandering when should the switch be disconnected at the start,later on or at all ?
Thanks again.
Dan
May 19, 2009 at 9:35 am |
Dan -
The idea behind the vacuum bleeding is to keep from mixing the two fluids.
I understand about not having the tool so here is an alternative method. It is called gravity bleeding.
It is using gravity to force the fluid to the bleeders rather than pressure or pumping the brake pedal. Pumping the brake pedal is to be avoided because it will stir things up.
I will assume that you have the vehicle safely up on jack stands with the wheels off. Keep the cap off the master cylinder reservoir and keep it full of fluid.
Put a clear hose on the bleeder screws and a plastic bottle at the end of the hose to catch the fluid.
Open the bleeder screws and let gravity drain the fluid for you. It will take a while. A long while.
Just be certain to keep the reservior from going empty.
After the bottles have collected a good amount of fluid you can close the bleeder screws and pump the pedal.
You can still go to a garage that has a vacuum bleeder, but it is likely that you will have flushed the system enough.
Best of luck, Jim
July 14, 2009 at 9:19 am |
I feel for Dan and his Volvo.. Hope all worked out for him.. His plight reminded me of some of the vehicles I have worked on…
I am a mechanic for the Army, and have had to repair quite a few HMMWV’s with issues related to contamination of DOT 5 with other fluids…
HMMWV’s (or Hummers, if you prefer) use DOT 5 fluid, but soldiers are sometimes ingenious at breaking things, and operating a vehicle with low brake fluid is a NO-GO, so… whatever is available WILL be put to use by those who wish to make it home on time.
The worst one I have worked on was a “heavy” (which has a nicely complicated brake system) that barely had brakes when I received it. I opened the MC to find it filled with what resembled grape jello. As I dug further and further into the system, I kept coming up with more and more purple goo…
I figured that this was a mix of DOT 5 and DOT 3 (probably scrounged or found, old and ‘wet’ from poor storage) in a rather ‘dirty’ system that was already overdue for maintenance. What can’t figure out is how it managed to so thoroughly mix throughout the entire system (unless the mixing occurred a LONG time before I eventually received it).
Much of the brake system ended up being replaced, and I had much fun launching long strings of purple spaghetti out of the stainless lines using compressed air…
The total job on that was a bit more than 18 hours.
July 14, 2009 at 5:30 pm |
J.Bob -
That is an amazing story! Thanks for sharing it with us. I groaned as I read your description.
Jim
July 15, 2009 at 1:22 pm |
I know you use a MityVac to suck the fluid out, but I have gone in the other direction. Motive Products makes a Power Bleeder ($50)which uses air pressure to bleed the brakes and like, MityVac, makes bleeding brakes a 1-person job. It works on Saabs, Volvos, BMWs and VWs, maybe some others.
Pour brake fluid into the hard plastic tank that’s a bit like a garden sprayer. Remove the cap from the fluid reservoir and replace it with the cap that is attached via a clear hose to the plastic tank. Pump the tank up to 15 PSI or so on the gauge.
Go to your bleeder, open it and out comes fluid and air. When the bubbles stop, close the bleeder and go on the the next wheel.
It works absolutely great, and can hold enough fluid to flush the entire system.
August 19, 2009 at 7:52 pm |
Hi Jim…Just have another question that you have answered but worried about having a problem. My Son just came home with his 97 Honda Accord Vetc. His Brake light was on so I checked Master cylinder and it was almost empty…so there is a leak. I had a new can of Dot 3 fluid so I added it. It was dark so I didn’t notice til we put the cap back on that it said DOT 4 only. Are we in trouble? Did I mess the system up? Won’t be able to get it checked out for a few days….Thanks Jim….
August 20, 2009 at 12:22 pm |
Wayne -
I don’t think you have ruined anything. If you can find a turkey baster or something like it you can suck out the fluid you put in and find some DOT 4.
When you bleed through the DOT 4 everything should be fine.
Jim
September 13, 2009 at 8:13 pm |
[...] Originally Posted by RockenZ you're right. I was thinking clutch and typed transmission. fixed. as far as this guys post on your other thread. the main difference between DOT3 and DOT4 is the boiling point of the fluid. The only concern with TEMP is in the BRAKE system, changing your CLUTCH fluid to DOT4 will do nothing for you. Probably the same as paying for a HIGH PERFORMANCE DOT3 fluid will do nothing for the clutch either. I say use the cheap stuff in the clutch and if you really abuse your car upgrade to a better DOT3 or DOT4 fluid for the brakes. "The difference between the DOT (Department of Transportaion) ratings of brake fluid are the boiling point ranges that they achieve both dry (no water absorbed) and wet (about 3-4% water content). For DOT 3 the dry boiling point is at least 401 and the wet 284 degrees. DOT 4 raises the bar to 446 and 311 respectively. Those are the DOT ratings mind you , and there are high performance brake fluids that exceed those ratings." taken from- DOT 3, DOT 4, and DOT 5 Jim’s Garage [...]
October 8, 2009 at 3:03 pm |
I have a 62 XKE convertable. I flushed the system and put DOT 5 in it years ago. I had the roters replaced and the mechanic cleaned the break fluid out and put in GT LMA without telling me. I noticed the clutch fluid was low and put in DOT 5. What is the best thing to do?
October 8, 2009 at 3:58 pm |
Very cool.
October 8, 2009 at 8:19 pm |
Kevin -
I assume you want to go back to DOT 5 – In that case you will need to flush out the GT LMA as soon as possible.
Sounds like you also need to find out why your clutch fluid was low. Unlike brake fluid your clutch fluid level should not change unless there is a leak.
Jim
October 10, 2009 at 7:24 am |
[...] sizes, but the difference in the fluids is the boiling point. This link talks about the differences DOT 3, DOT 4, and DOT 5 Jim’s Garage. __________________ Brad 2003 F-250 Lariat Supercab 4×4 6.0L PSD, Fumoto, Updated HFCM Plug, [...]
October 13, 2009 at 3:40 pm |
[...] mind you , and there are high performance brake fluids that exceed those ratings. Reference: DOT 3, DOT 4, and DOT 5 Jim’s Garage __________________ ——————————————– '07 Black Cherry, every option [...]
November 1, 2009 at 2:37 pm |
[...] DOT 3, DOT 4, and DOT 5 Jim’s Garage [...]