Where's my brake fluid going?
Moderator: Fatmobile
Where's my brake fluid going?
I've got plenty of brake pressure. Always stops good.
At the end of the day driving, the level is down a 1/4'' to 1/2''.
I can't find any leak anywhere. New wheel cylinders installed.
Any ideas? Thanks.
At the end of the day driving, the level is down a 1/4'' to 1/2''.
I can't find any leak anywhere. New wheel cylinders installed.
Any ideas? Thanks.
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Re: Where's my brake fluid going?
What kind of car??/
Early Rabbit '79ish? Check under passenger carpet.
Early Rabbit '79ish? Check under passenger carpet.
'91 Golf gasser converted to a 12mm pump, M-TDI.
'84 1.6TD Rabbit with a VNT-15 turbo, still setup to run on vegetable oil.
'84 GTI with 1.7TD pistons and intercooled.
2003 TDI wagon
2000 TDI Jetta.
'84 1.6TD Rabbit with a VNT-15 turbo, still setup to run on vegetable oil.
'84 GTI with 1.7TD pistons and intercooled.
2003 TDI wagon
2000 TDI Jetta.
Re: Where's my brake fluid going?
If you don't find it in the area of the passenger area as fatmobile says, have the car sit in the driveway and push on the pedal many times and see if you can find a spot somewhere. It may a very small leak and show up now, or more later. It could be a leak that's going into the brake booster if the master cylinder is starting to go out on the main pushrod.
Everybody else lists their cars here - but not me.
I have too many to count
I have too many to count
Re: Where's my brake fluid going?
Sorry about that. It's a '81 pickup.
I'll check the floor mat.
I've put it up on ramps and pumped the brakes like crazy, but everything is dry underneath.
Anyway to check the brake booster or master cylinder before I pull it all apart?
I'll check the floor mat.
I've put it up on ramps and pumped the brakes like crazy, but everything is dry underneath.
Anyway to check the brake booster or master cylinder before I pull it all apart?
Re: Where's my brake fluid going?
Not sure about the pickups but the US built Rabbits (or at least post 1980) routed the rear brake lines outside the body. My 79 accumulated about a half quart in the rear carpet before I figured out where that leak was.
My 82 had a leak near the rear swing arm mount before it let go completely or at least I assume so since mine went down a tiny bit too before blowing the steel line in traffic one night. Glad there was a grassy median to pull onto that time.
If it's going down it's leaking somewhere and a careful inspection of all the lines is in order. I have heard of cases where fluid leaked past the master cylinder seal into the booster. I think you can loosen the nuts holding the master cylinder on enough to pull it forward and look for moisture and you can probably do that while still leaving all the lines attached.
My 82 had a leak near the rear swing arm mount before it let go completely or at least I assume so since mine went down a tiny bit too before blowing the steel line in traffic one night. Glad there was a grassy median to pull onto that time.
If it's going down it's leaking somewhere and a careful inspection of all the lines is in order. I have heard of cases where fluid leaked past the master cylinder seal into the booster. I think you can loosen the nuts holding the master cylinder on enough to pull it forward and look for moisture and you can probably do that while still leaving all the lines attached.
Bob
'06 Jetta TDI
'82 Rabbit 1.6NA
Honda, 99 GMC Suburban, '41 Chevy Coupe
'06 Jetta TDI
'82 Rabbit 1.6NA
Honda, 99 GMC Suburban, '41 Chevy Coupe
Re: Where's my brake fluid going?
No clue how to inspect booster first since its sealed and on the car.
But I junked an 82 jetta this year and wanted to use the booster and found my master must have pushing it in there because I tipped it over and got wet with nasty stuff
But I junked an 82 jetta this year and wanted to use the booster and found my master must have pushing it in there because I tipped it over and got wet with nasty stuff
1985 jetta turbo diesel, 5 speed manual
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Re: Where's my brake fluid going?
You pretty much have to pull the master cylinder to see if it's leaking into the booster.
Probably is.
Doesn't mean you need to replace the booster,.. but you'll need to clean and dry it good.
There is an o-ring on the end of the master cylinder and since the master cylinder is still working you could probably get away with just pulling it apart, cleaning it up and finding a replacment for that o-ring.
Most people would just get a new master cylinder,.. I don't think you can even get a master cylinder rebuild kit anymore.
Probably is.
Doesn't mean you need to replace the booster,.. but you'll need to clean and dry it good.
There is an o-ring on the end of the master cylinder and since the master cylinder is still working you could probably get away with just pulling it apart, cleaning it up and finding a replacment for that o-ring.
Most people would just get a new master cylinder,.. I don't think you can even get a master cylinder rebuild kit anymore.
'91 Golf gasser converted to a 12mm pump, M-TDI.
'84 1.6TD Rabbit with a VNT-15 turbo, still setup to run on vegetable oil.
'84 GTI with 1.7TD pistons and intercooled.
2003 TDI wagon
2000 TDI Jetta.
'84 1.6TD Rabbit with a VNT-15 turbo, still setup to run on vegetable oil.
'84 GTI with 1.7TD pistons and intercooled.
2003 TDI wagon
2000 TDI Jetta.
Re: Where's my brake fluid going?
Well I pulled out the vacuum hose from the brake booster and inserted a small rubber tube attached to a syringe and pulled brake fluid out.
So that solves where it was going. Would this be from a o-ring failure or the master cylinder?
I have a new mc I'm going to install, I was just wandering.
So that solves where it was going. Would this be from a o-ring failure or the master cylinder?
I have a new mc I'm going to install, I was just wandering.
Re: Where's my brake fluid going?
Bad master cylinder for sure. Hope you can dry out the booster.
Bob
'06 Jetta TDI
'82 Rabbit 1.6NA
Honda, 99 GMC Suburban, '41 Chevy Coupe
'06 Jetta TDI
'82 Rabbit 1.6NA
Honda, 99 GMC Suburban, '41 Chevy Coupe
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- Global Moderator
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- Joined: Wed Oct 30, 2002 10:28 pm
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Re: Where's my brake fluid going?
Bad o-ring inside the end of the master cylinder plunger.
Nice way to check for fluid in the booster.
Nice way to check for fluid in the booster.
'91 Golf gasser converted to a 12mm pump, M-TDI.
'84 1.6TD Rabbit with a VNT-15 turbo, still setup to run on vegetable oil.
'84 GTI with 1.7TD pistons and intercooled.
2003 TDI wagon
2000 TDI Jetta.
'84 1.6TD Rabbit with a VNT-15 turbo, still setup to run on vegetable oil.
'84 GTI with 1.7TD pistons and intercooled.
2003 TDI wagon
2000 TDI Jetta.
Re: Where's my brake fluid going?
Double kudos on the idea to check for fluid. Pretty good thinking on that one.
Brake fluid attracts moisture, and will eat the paint off anything. So, when you change out the master cylinder, get as much of the brake fluid out of the booster as you can. Not sure if there's anything that you can put in there to slosh around to clean it out, or if this makes things a lot worse.
Brake fluid attracts moisture, and will eat the paint off anything. So, when you change out the master cylinder, get as much of the brake fluid out of the booster as you can. Not sure if there's anything that you can put in there to slosh around to clean it out, or if this makes things a lot worse.
Everybody else lists their cars here - but not me.
I have too many to count
I have too many to count
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Re: Where's my brake fluid going?
x2 on washing out if you can. My vaccum diapham on my stepvan usually lasts about 5 years. My rebuilder told me that the brake fluid will eat the diapham evenually. I have hooked a vacuum gauge up to it. 6 tons is hard to stop without it.
99 TDI Jetta (Z1 engine code)
94 Grand Caravan
89 Dodge Gold Stream B class
http://www.antiquedollhouseofpatterns.ca/
94 Grand Caravan
89 Dodge Gold Stream B class
http://www.antiquedollhouseofpatterns.ca/
Re: Where's my brake fluid going?
I've got a spare one on a parts truck. I think I'll just swap it out and let the other one dry out after I try to clean it.
Every so often I have an original thought, by accident.Fatmobile wrote:Nice way to check for fluid in the booster.
Re: Where's my brake fluid going?
So now I've put on the new master cylinder and it's leaking out both rubber plugs that the fluid reservoir goes into.
Do these need to swell up before they hold fluid?
I haven't even bled the brakes yet so there is no pressure.
There is a drip coming out both plugs about every 10 seconds or so.
What gives?
Do these need to swell up before they hold fluid?
I haven't even bled the brakes yet so there is no pressure.
There is a drip coming out both plugs about every 10 seconds or so.
What gives?
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- Global Moderator
- Posts: 7566
- Joined: Wed Oct 30, 2002 10:28 pm
- Location: north central Iowa
Re: Where's my brake fluid going?
That isn't common.
I'm not sure why the rubber plug wouldn't seal around the plastic resevoir barbs.
Did you pull the rubber plugs and clean them out?
Take care with the plastic resevoir unless you have a spare. NLA.
I'm not sure why the rubber plug wouldn't seal around the plastic resevoir barbs.
Did you pull the rubber plugs and clean them out?
Take care with the plastic resevoir unless you have a spare. NLA.
'91 Golf gasser converted to a 12mm pump, M-TDI.
'84 1.6TD Rabbit with a VNT-15 turbo, still setup to run on vegetable oil.
'84 GTI with 1.7TD pistons and intercooled.
2003 TDI wagon
2000 TDI Jetta.
'84 1.6TD Rabbit with a VNT-15 turbo, still setup to run on vegetable oil.
'84 GTI with 1.7TD pistons and intercooled.
2003 TDI wagon
2000 TDI Jetta.