Changing brake fluid....

[scott s]

 I've often read that brake fluid absorbs moisture and needs to be changed on a regular interval.
 I, for one, have NEVER changed the brake fluid in any car I've ever owned. I don't even think cars that I've had dealer serviced have had it done. Heck, I don't even KNOW anyone who's had it done.
 How many of you actually change the brake fluid? What's your schedule? How do you "purge" all the old fluid out of the lines, wheel cylinders, etc.?
 The reason I'm asking is b/c I'm putting all new disc/drum brakes on the '70 next week. For all I know the fluid is original from Germany in that car. Just about every other element of the braking system will be new. How important is it to change the fluid? Is there a particular brand you guys like?
 I digress...I did put all new fluid in my '63, but that's b/c it was basically dry to start with. It's been in the for about 10 years now, though...

[Bad Bug Two]

Scott,

It would be a good idea if everyone changed their brake fluid every couple of years, but almost no one does... including myself... and I know better!  There are a lot of maintenance issues on cars that don't get done.  Any case back to the brake system...

I'd just use regular DOT 3 fluid.

I would just bleed the system out how ever you normally do, (Two person, gravity, pressure, or ?), until you get clean fluid at all four corners.  If you want, you might  be able to use a turkey baster to suck out the resevoir before you start.  Also, on our older cars, it is very possible to have a brake hose that still looks okay from the outside, but is coming apart on the inside causing all kinds of weird pulling issues.  I would just step up and replace all four of the flexible hoses!  Also don't forget to check the steel line that runs the full length of the car, especially around the pedals.  If there is any sign of rusting, just replace it now and be done with it!

Oh yea one final thing.... as you are going to be replacing components, it would be best, in my opinion, to flush out the sytem, or what will be left of it!, before putting in the new stuff so you aren't pushing old fluid through the new cylinders and calipers!

Good luck!

 

[The Inspector]

Was that a Brake Fluid Salesperson that has been telling you ya need to change it regularly?

[Alan Uyeno]

Dot 3 is all you need. If you were autox your car on a road track it'd be better to use  a dot 4 or dot5.1.  I'm talking polyglycol based here.

Silicon based dot 5 gets mushy even though theres no air in the system.

Make sure you have 2 people. I've used the Vacula at my shop and it sucks the fluid out of the bleeding nipples. Then I let it either gravity bleed for a while or I'll manually pump with someone helping me crack the nipple open and closed at the wheel cylinders.
 
or manually just pump and pump till the fluid turns apple juice color. You can buy a cheap check valve to put on the nipple to help you prevent sucking air.

Scott I'll warn you now that the VW beetles are real friggen stupid when it comes to bleeding. When the nipple is cracked open the brake pedal will go to the floor and stay there. Sometimes you'll need to literally kick it back up with your foot or use your hand to move it up.

[Bad Bug Two]

Was that a Brake Fluid Salesperson that has been telling you ya need to change it regularly?

 

No, I've just been teaching Automotive Technology for about 10 years now, I'm use to preaching what should be done... even if I don't always follow my own advise!

 

[John Palmer]

Also, on our older cars, it is very possible to have a brake hose that still looks okay from the outside, but is coming apart on the inside causing all kinds of weird pulling issues.  I would just step up and replace all four of the flexible hoses!

This is VERY GOOD advice and is often overlooked when chasing brake problems.

[Bruce Tweddle]

Scott, flushing the brake juice every 2 years is what virtually every automaker advises.  If eveyone did that, no one would ever need to buy new master cylinders, wheel cylinders or brake calipers.  Flushing the system is much more important if you live in a damp climate since the brake juice extracts moisture from the air. 

If every component in your system is new, consider DOT 5 silicone.  It never needs replacement since it does not pull moisture out of the air like DOT 3 & DOT 4.  You can treat it like everyone treats normal brake juice.

VW beetles are real friggen stupid when it comes to bleeding. When the nipple is cracked open the brake pedal will go to the floor and stay there. Sometimes you'll need to literally kick it back up with your foot or use your hand to move it up.

Maybe that's due to that damn Super Beetle MC you have.

[scott s]

 I've bled brakes plenty of times, so I know how to do that part. I've just never changed the fluid like you would, say, the oil.
 When I say every part new, I mean from the body out; i.e., hoses, backing plates, wheel cylinders, calipers, shoes, etc. The hard line in the body and the master cylinder and resevoir will stay as they are.
 I've considered doing the turkey baster thing. That way I'd have less old fluid to push out when bleeding. If I do that and basically fill up a fresh system I should have most of the old fluid out, right?

[martin]

If you're a brake fluid changer, you may want to buy one of the $50 pressure bleeders. I've got one and it works fine, provided you have good hoses between the reservoir and the mc, otherwise when you pressurize it, it leaks all over. Makes the job a breeze.

[Jerry D]

As everyone knows, Brake fluid absorbs moisture from the air (hydroscopic). The moisture sits in the steel brakelines and starts to corrode them. Most of the time when a steel brakeline fails, it fails from the inside out, because of rust caused by moisture in the fluid.
I use a "MityVac" on the brake bleeder and draw the fluid out of the system before installing new fluid.
Jerry...   

[Ed Brewer]

I agree that brake fluid should be occasionally changed.  Every two or three years is a fair interval.  DOT 3 is fine.  I simply bleed the brakes as usual until the fluid comes out clean.  I have done it using the typical two person method, and by using a vaccuum pump (Mity-vac).  Both work fine.

Unless the rubber in the brake system is designed for DOT 5, do not use it!  DOT 5 can swell the flex lines shut inside so that no fluid can flow through, which equals no brakes.  I have seen this happen.

[Bruce Tweddle]

DOT 5 can swell the flex lines shut inside ....... I have seen this happen.

That happens with DOT 3 fluid.  I guess it means the flex lines are not compatible any brake fluid. 

I've never seen any warnings on DOT 5 brake fluid or on any brake component.  IMO, if it was a problem, there would be a warning.

[martin]

I thought you were a DOT5 silicone hater, Bruce? What changed your opinion?

[Bruce Tweddle]

You got that backwards, Martin.  I've been a DOT 5 champion for a long time.
Many online experts (that have never used DOT 5) warn of disasterous failure by using DOT 5.  I've been waiting for 15 years to see any effects in my yellow car.  Five years in my Mexican Bug.

[martin]

o, ok, maybe it was you that said the brake lite switches don't last with DOT-5 then? if so, I came up with a solution in the last years by which I added a relay to the brake lite circuit taking the arcing out of the feeble little switch, works solid, and you can hear a faint click telling you that the brake lites should be on.

[Bruce Tweddle]

o, ok, maybe it was you that said the brake lite switches don't last with DOT-5 then?

Nope. never heard that one.  All my switches are original.

[Mag00]

Make sure you have 2 people. I've used the Vacula at my shop and it sucks the fluid out of the bleeding nipples. Then I let it either gravity bleed for a while or I'll manually pump with someone helping me crack the nipple open... use your hand to move it up.

Yikes!!!!

[Anton]

Bruce, i work at Audi dealer, used to work at VW, and i have seen the disasterous consequenses you speak of that cost a few thousands of dollars when some fast and furious kid (not calling you that) wants to have blue brake fluid to match the flourecent lights under the car. well when his entire brake system fails we replace the abs pump(module) master cylinder, all the calipers and lines, so personally i would never recommend using that crap(dot5 that is),
a fellow racer once asked me about using it, i told him what i thought about it, well he did it anyway, few days later he was complaining about mushy brake pedal and that it was sticking, he ended up replacing all the seals in the calipers, and replacing the master cylinder. i got more horror storys if you want

as far replacing the brake fluid, we (dealer) change it as a part of 2 year maintenance

[Bruce Tweddle]

How long am I supposed to wait?

Were these cars converted properly by cleaning out all traces of the old fluid, or did they ignorantly mix the two?

[martin]

That's a little hard to believe as these companies selling DOT5 would be sued out of existance, but no, it's still on the market decades later, hmmmm. Bruce, that's probably why you're not having problems with your brake lite switches, the OG ones aren't as problematic as the newly produced Brazil or whatever ones. I have installed a good used one most recently and it's still working. I have DOT5 in three bugs and while each has it's own braking personality, there doesn't seem to be any anomolies caused by the fluid. I love the fact that it doesn't remove paint if spilled.

[Gibber!]

If you're a brake fluid changer, you may want to buy one of the $50 pressure bleeders. I've got one and it works fine, provided you have good hoses between the reservoir and the mc, otherwise when you pressurize it, it leaks all over. Makes the job a breeze.

I've got a pressure bleeder too, makes the job a lot easier- and a one man job too!

Everyone should bleed their brakes everytime they change pads or shoes. If you weren't to, every time you change the pads (for example) and push the pistons back into the caliper, the same crappy fluid that has been heated by your brakes in the caliper is then kept in the system.  Just opening the nipple and pumping a couple of times will at least get 'cleaner' fluid into the caliper.

G-out!

[Jerry D]

I have been running DOT 5 in my 33 Ford for 20,000 miles, in my Manx for 3 years, in my Baja for 3 years and in my brother's 52 Chevy for 8 or 9 years with no problems at all.
Jerry...