Just hit the floor with the brake peddle. Checked the master cylinder and no fluid. When I see which seal has gone is Dot3 okey dokey to use to stop my chariot. It's a 36 Ford
flush whole system & refill with dot 5 - the dot 5 wont draw moisture and you wont have any more bad seals
DOT3 is fine, DOT4 has a higher boiling point. Whatever you use make sure its from a sealed container.
Dot l5 is silicone brake fluid and I wouldn't recommend using it in any brake system that had had dot 3 fluid without following the prescribed procedure for flushing the system. Dot 5 originally showed up on the Fiero's as there was a worry about Dot 3 damaging the plastic bodies. It also came out in Corvettes about the same time for similar reasons and rodders picked up on it because it didn't damage paint if you spilled on your paint or got some on painted backing plates or the axle when you bled the brakes. That was the big selling point for Dot 5 for hot rodders. Personally I have never seen the need to use anything except Dot 3 or possibly dot 4 myself but I do suggest flushing the old fluid out with new fluid every season on cars that sit for long lengths of time. On the Dot 3 though, the NAPA EIS brake rep told us not to buy more brake fluid for our shops than we could use up in a set period of time as the fluid draws moisture setting in the can if it sets around for long periods of time. He said even though he sold gallon and five gallon cans of brake fluid he didn't like to see shops that didn't have high volumes of brake work buy that large of quan***ies to keep around. He didn't like the pump setups to put in gallon cans either for the same reason.
DOT 5 brake fluid has been around A LOT longer than Fiero's LOL It was used in racing back in the 1970's because of it's higher boiling points, but then many race teams abandoned that practice because it is somewhat compressible as it has the ability to absorb air into the molecules. As it absorbs more air, the brakes become more spongy and the hardness of the pedal goes away. I think it has been around since the 1960's, although it did not really find any widespread usage until the 1980's. It is Not hydroscopic like DOT 3 and 4, which means it won't absorb water from the atmosphere, but it can trap water that gets in the system from say a non sealed cap, again causing a spongy pedal. DOT 5 can take quite a bit longer to bleed and get a good firm pedal because of it's attraction to the air on the system. Harley Davidson has used DOT 5 brake fluid for many years, (at least since the early 80's) mainly because it doesn't hurt the paint. But many Harley riders have experienced a loss of brake pressure at high elevations on a hot day due to the absorption of air in the fluid. They do NOT use it in High Performance bikes or anything with ABS as DOT 5 is Not compatible with any ABS systems, due to the compressibility issues and the fact that it is a poor lubricant so it is hard on the ABS pump. If you are considering using DOT 5 it is best to do so when overhauling the brakes. The reason being is any residual Glycol based fluids left in the system will tend to create "Slugs" which can block the system. Any water that is in the system from the old fluid will tend to puddle in the low spots and cause brake pedal issues. And lastly, the combined fluids have been known to cause havoc with seals. It is best to take the system apart and thoroughly clean all parts with Brake Cleaner then introduce the DOT 5 silicone. Because it does not absorb water from the atmosphere, it is good for a car that isn't driven a lot as it will cut down on the corrosion of brake cylinders and lines. Unlike Glycol fluids that should be changed every 2 years (although very few people ever due, and pay the price years later) Silicone will last for many years if the cap on the master is kept dry and tight. As a side note, by DOT regs, Glycol based brake fluids are clear to yellowish and DOT 5 is Purple. And Mr48Chev, your NAPA guy was right. You should not use bigger bottles or cans of fluid than you will use up in a month or two's time as it will start absorbing lots of air. Old containers of brake fluid that have been opened should be disposed of as the fluid will be contaminated before it ever goes in the car.
Dot 3/4 fluid is more than adequate for most brake systems. Personally prefer Castrol LMA. Although it doesn't have the highest dry boiling point, it does have the highest wet boiling point of the more wallet friendly fluids. What is really nice about LMA is that it stays clear for a very long time. Then when it begins to go off it turns brown pretty quickly. And most auto stores sell it by the pint/litre/gallon. Castrol SRF is(was?) re-bottled by Ford as their HD Dot 3 for years, but things have changed a bit, it is now called Ford High Performance brake fluid. Is it still a cheap way to purchase SRF*shrug*. http://www.timskelton.com/lightning/race_prep/brakes/brake_fluid.htm As hotroddon stated. Dot 5 is old and busted, even though it is hydrophobic(it will not mix/absorb water) this does not mean water will not get into the system. Even worse, it will keep water separated, which can cause areas in the brake system that will have severe corrosion. There is no way to know if water/moisture is in the fluid unlike hygroscopic fluid which turns color. Dot5 can absorb air, which will lead to a sponge pedal. DOT 5 is not cheap either. If you need a boiling point of Dot 5, Dot 4 comes pretty close, if not Dot 5.1 <table border="1"><tbody><tr><td>DOT 3</td> <td>205 °C (401 °F)</td> <td>140 °C (284 °F)</td> </tr> <tr> <td>DOT 4</td> <td>230 °C (446 °F)</td> <td>155 °C (311 °F)</td> </tr> <tr> <td>DOT 5</td> <td>260 °C (500 °F)</td> <td>180 °C (356 °F)</td> </tr> <tr> <td>DOT 5.1</td> <td>260 °C (500 °F)</td> <td>180 °C (356 °F)</td></tr></tbody></table> 5.1 can be used in systems that use Dot 3/4 without any adverse affects out of the ordinary.
I would not change fluid type unless I was changing/rebuilding all the cylinders, no mater how well we flushed the system, they always seem to fail soon after.
While we're at it... Probably the best brake fluid you can get for a stret car is Ate. Ate Super Blue Racing or Ate typ 200. Both are the same, the difference is typ 200 is goldish and Super Blue Racing is blue. The idea is that when you do flushes you alternate between the fluids as the colors are different. It's sold as DOT4 but the specs on it exceed DOT5.1. The only caveat is that the blue fluid may not be street legal, but who's going to check? I recently flushed the brakes in a few of my cars and they have either typ 200 or super blue. Probably overkill but for $15 a liter its worth being overly cautious.
No. Nope. Nuh-uh. No way. Fuggetabou***. As previously mentioned Dot 5 will still absorb moisture and worse air. But since the moisture does not mix into the siliicone you cannot tell it is there, it will ac***ulate somewhere in the system and rot it out. Normal Dot 3/4/5.1 will turn color as it will mix with the moisture, and when the moisture increases the color of the fluid will change. Giving a very easy visual indication of 'wet' brake fluid. Simply use a quality Dot 3 or 4 fluid and be done with it. The other 'advantage' to Dot 5 I've heard over the years is it does not affect paint. I've spilt my fair share of Dot 3/4 on paint, and as long as you don't let it sit, it will not immediately harm the paint as long as you wash it off with some water. Accidentally dumped about a cup of LMA on the fender of my OT car, poured water on it and you cannot tell where the fluid was spilt. EDIT: FWIW I can find LMA locally for ~ $8/litre. And recently picked up a gallon of LMA for ~$30. I had a few cars to do. I will preach on it is the best bang for the buck.
If you do not want silicone fluid, always pick up a dot 4 in preference to a dot 3. I ran clutch slave cylinder tests some time ago and they lasted better with dot 4. One actually failed with dot 3 and p***ed with dot 4. Mart.
DOT 3 is so ****py that its hard to believe that the Federal Government still allows it to be used. DOT 5 only
Really? REALLY?!? First... 5, and then 5.1 does not absorb moisture, so it can't rust anything. Second... I just... really?
I believe it. Since silicone fluid isn't hygroscopic it won't absorb moisture, moisture tends to then collect in the lowest parts of the system; in this case it's the wheel cylinders.
This argument will go on as long as there is any interest in cars, I'm afraid. My own old cars (8 of 'em over the years) have had DOT5 in them since 1984 without any failures. One of the cars I still have, a 1937 Chevy Sports Coupe, I switched over to DOT5 in 1991 and the fluid has been changed about every 7 or 8 years. The hardware is still the same, except for the M/C which was changed because I switched to a dual M/C. When I switched to DOT5, I completely rebuilt the entire brake system, installed all new rubber components and blew out the hard lines with solvent. In my opinion, any car that sits for extended periods of time is much better off with DOT5. Just my opinion based on my experiences.
yes REALLY - although DOT 5 is Not hygroscopic, meaning it can't absorb water from the atmosphere, water can still enter the systems and when it does it will congregate in the lowest parts of the system, so Yes this is possible. As for 5.1 it IS Hygroscopic, meaning it does absorb water from the atmosphere. it is still a Glycol Ether based fluid, and as DOT 3 and DOT 4
Castrol GT LMA is an interesting special case. It is currently rated as essentially DOT 4. The LMA means Low Moisture Absorbent and the reason for that it is a Glycol based fluid that has Silicone in it! Not enough to hit the 70% mark that is what makes DOT 5 fluid rated the way it is. it will still hurt paint, but does seem to offer better corrosion resistance with higher that normal DOT4 temperature ratings. it can be mixed with conventional brake fluids, but not DOT5
Yep. The silicone fluid does not mix with water, & the water sank down to the lowest point in my system & severely pitted out my cylinders. Since then, I've learned that brake fluid is made to absorb water "by design" due to the dead-headed nature of hyd brake systems. DOT 3/4 will absorb water, but it also keeps it in suspension, avoiding rust issues. Standard brake fluid will get muddy when it's at it's max saturation point. Most car maker recommend flushing out the system every 4 years. As far as fluid, I only use BMW Dot 4. I don't have the part #, but it's good stuff. You know, the funny thing is that this thread reminded me that my daily driver needs a flush - been 5 years. I just made an apt to get it done.
Castrol "GT LMA" is Low Moisture Activity which is a Dot 3/4 fluidwith advertised boiling points of 446/311.The newer Castrol "Brake Fluid Dot 4" is synthetic(like the original) and called an LMA fluid on the back, which it is, and has boiling points of 509/311. Actually, the black bottles of "Brake Fluid Dot 4" are just redesigned "GT LMA" bottles, which contains the same formula of fluid. I believe it was new SAE testing that allows Castrol to rename GTLMA from a 3/4 to a 4. Neither have any literature stating they have any silicone in them, and both are designed for disc/drum and ABS equipped systems. These are both glycol ester based fluids. Strangely enough, I am fairly positive that it is Castrol Dot 4
Someone above stated Dot 5 should be put in all new cars. I used to be the brake engineer at a GM ***embly plant. We got the contract to build Post Office vehicles. The gov't mandated we use Dot 5. We had to build a separate area to build those vehicles because silicone in the wrong area of an ***embly plant can cause havoc in paint and paint repair areas. Rags used to clean up a silicone spill getting in to the paint house can cause hundreds of ruined paint jobs. Just a little FYI. We pulled a vacuum in our equipment to cook out moisture and we tested it hourly to ensure the boiling point was 470 degrees or better.
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