Brakes go to the floor, help!

Cacree

Member
Joined
Jan 23, 2012
Location
Colorado
TDI
1998 Beetle, 2015 Passat
My 98 Beetle has terrible brakes. They are terrifying. The pads and rotors themselves are in great condition, I just had the master cylinder and brake booster replaced because it was leaking, I thought that would help and it only made it worse. My brakes now go all the way to the floor before applying. I was told maybe the vacuum pump? The outlet on the vacuum pump was very very loose so I sealed it with some JB weld and that’s doesn’t seem to have helped at all. Do these vacuum pumps fail internally? How would I test that?
 

turbodieseldyke

Veteran Member
Joined
Jun 6, 2010
Location
Free Mustache Rides
TDI
98 jetta
Air bubbles in the fluid? I thought a bad vacuum would give the opposite effect on the pedal -- make it really hard to push. You can test the vacuum by hooking up a gauge.
 

KrashDH

Veteran Member
Joined
Dec 22, 2013
Location
Washington
TDI
2002 Golf
You can test your vac pump by hooking a MightyVac to it and reading how much vac builds and how quickly.

If your booster fails, or vac pump fails, soft brakes aren't the symptom...hard, stiff pedal is. Vacuum is used to assist the breaks, so it's kind of common sense if there is no assistance, then your leg will be doing all the work, and it's a lot of push to get the car to brake.

Sounds like you have air in the system somewhere. I would follow the FSM and do a full bleed. You will need VCDS for it since you will want to bleed the pump to eliminate that.
 

BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
Well this is serious, dangerous even. Was the system flushed/bled? Something must be leaky, caliper, brake lines.
 

ToxicDoc

Veteran Member
Joined
Mar 1, 2018
Location
Virginia, US
TDI
2001 Jetta, S7, .216
You do not have a vacuum problem. You have a lack of hydraulic pressure problem. Take it back to the shop, ask them to look it over, consider maybe it just needs better air bleeding (that should be at no cost to you if they didn't do it right). A leak is possible but seems less likely if your mechanic had even half a skill set.
 

Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
Northern MD (HAGERBUSH)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress)
Depending on how things where done, you probably have trapped air in the lines and in the abs.
No issue with vaccum that would be a hard non assisted feeling going all the way to the floor is lack of fluid.
 

Wilkins

Veteran Member
Joined
Aug 19, 2005
Location
British Columbia
TDI
05 Jetta Wagon 5sp, 10 Sportwagen 6MT
I’m not sure I would completely disregard the vacuum pump as a potential cause. Totally agree the first check is to bleed any air out but I just went through something similar and flushing and bleeding didn’t fix the problem completely. A new vacuum pump did.

In my case the pedal would be hard until I started the engine then would go nearly to the floor.
 

KrashDH

Veteran Member
Joined
Dec 22, 2013
Location
Washington
TDI
2002 Golf
I’m not sure I would completely disregard the vacuum pump as a potential cause. Totally agree the first check is to bleed any air out but I just went through something similar and flushing and bleeding didn’t fix the problem completely. A new vacuum pump did.

In my case the pedal would be hard until I started the engine then would go nearly to the floor.
You either had 2 separate issues then or you were pumping the pedal a couple times with the car off. There is only so much vac storage built up in the booster when the pump isn't running. You pump the brake with the car off, it uses all that, pedal becomes hard. If this isn't the case, then you had a small vac leak somewhere causing the stored vac to bleed off.

The pedal to the floor is a separate issue.

Check the vacuum line that goes to the master cylinder. They tend to crack with age. Very easy fix if that is all it is.
This has been discussed in numerous posts above. This would result in a hard pedal. There are good videos on the interwebz of how vac systems work with brake boosters if you are not familiar. It's a good watch.
 

VWMatt

Well-known member
Joined
Mar 6, 2013
Location
Pennsylvania
TDI
2002 Golf TDI
This has been discussed in numerous posts above. This would result in a hard pedal. There are good videos on the interwebz of how vac systems work with brake boosters if you are not familiar. It's a good watch.
Comment deleted. Good luck
 

Cacree

Member
Joined
Jan 23, 2012
Location
Colorado
TDI
1998 Beetle, 2015 Passat
Well this is serious, dangerous even. Was the system flushed/bled? Something must be leaky, caliper, brake lines.
I had it the master cylinder and brake booster replaced at a shop, so I would assume he did the whole flush/bleed, but the brakes went almost all the way to the floor beforehand so I thought that would fix the issue as it was leaking.
 

burn_your_money

Veteran Member
Joined
Oct 16, 2012
Location
North Bay, ON
TDI
99 Beetle, 96 B4V, 05 Passat wagon
I'm shocked that a mechanic would let a car leave with brakes that bad.
I would first give all the brake components a visual to verify that there are no leaks. I've had issues in the past with the bleeders leaking.
The most likely cause is air trapped in the system. Master cylinders can be hard to bleed and are usually bled on the bench. As mentioned, the ABS pump can also trap air in it and it needs to be cycled with VCDS while bleeding.
Once you are 100% sure it is bled properly, and there are no leaks, then I would fully apply the brakes and look at all the flex hoses. They can balloon out under pressure and cause excessive pedal travel. I would also ensure that all the calipers and sliders are functioning properly and not moving excessively.
 
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