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?
Brakes go to the floor, help!
- Thread starter Cacree
- Start date
turbodieseldyke
Veteran Member
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
Top Post Dawg
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.
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
Well this is serious, dangerous even. Was the system flushed/bled? Something must be leaky, caliper, brake lines.
ToxicDoc
Veteran Member
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
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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.
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
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.
In my case the pedal would be hard until I started the engine then would go nearly to the floor.
KrashDH
Top Post Dawg
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.
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
Comment deleted. Good luck
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
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.
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.