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Re: Problem with brake fluid.... Posted by eric in vermont [Email]  (#2058) [Profile/Gallery]
(more from eric in vermont) on Tue, 25 Mar 2008 15:22:08
In Reply to: Problem with brake fluid...., Slyde, Tue, 25 Mar 2008 13:51:34 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Oh boy...this could be a problem.
DOT 3 and DOT 4 are glycol based and are NOT compatible with DOT 5. DOT 5 is a silicone based brake fluid and introduction of DOT3/4 is bad, bad, bad! You will totally ruin your brake system!
If you truly have DOT 5 in there and wish to go back to DOT3/4, your only choice is to completely renew every brake seal in the system and flush out the lines. That means the brake master, the front calipers, and the rear cylinders. The same is true if you have DOT 3/4 and want to go to DOT 5.
How do I know this? I bought one of my Sonetts with a leaking master cylinder. I did some research and found out that a previous owner had converted to DOT 5. The last owner before me had a bad brake hose- had a garage change it and they topped off with DOT 3. Everything turned to...junk after that. So I had to replace the whole shooting match!
DOT 5 is a light purple color. Maybe you can drain a little and see the color. The other method is to buy a pint of DOT 3- smell it and feel it between your fingers to see what it's like. Don't drink it- it tastes terrible! Then do the same with the stuff in your car. You should be able to discern if its the same or different.
If you are going to use DOT 3, I highly recommend Castrol LMA for VSaab brake systems.
If it is indeed DOT 5 in your car, then you should make certain that you drain your fluid at the lowest point. DOT 5 does NOT absorb moisture- and moisture DOES get into your brake system- so it pools at the lowest point. Bad if its near the caliper 'cause it can boil, turn to steam and you have no brakes! It should be changed out completely every 2 years to get rid of the moisture buildup.
DOT 3/4 based fluids DO absorb moisture- by design. It's not a bad thing! These have moisture absorbing additives designed to absorb the moisture that gets into your brakes such that it doesn't pool. You have to worry about two things- as moisture is absorbed, the boiling point of the fluid goes down... and... the moisture absorbing additives get used up. So you still need to change/flush your fluid every couple of years.
Sorry to go on and on about this- but brakes are kinda important in a car and I've been through the whole DOT3/4 vs DOT5 thing before. Let me know if you have more questions...
Eric in Vermont
posted by 68.142.42...
, Tue, 25 Mar 2008 15:22:08 <-- Viewing This Message, Tue, 25 Mar 2008 16:22:54, Tue, 25 Mar 2008 16:42:19
, Wed, 2 Dec 2015 11:52:15, Wed, 26 Mar 2008 12:10:53
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