Lousy Brakes, Vacuum leak?

[IDoSeaDoo]

I was in a hurry a few times during the past few weeks, and have had to stop pretty fast a few times. During this, I noticed that my brakes straight SUCK! If trying to slow down pretty hard, I'll apply a ton of force to the pedal, but it will slow down only slightly, not even really jerking me forward. Then, as the car slows down more and more, the brakes suddenly come out of nowhere and grab the rotors VERY hard, causing me to finally jerk forward. It's as if the force on a rotor is exponentially delayed. I'm going to the beach and towing a 1200lbs trailer. Naturally, this brake problem makes me quite concerned.

I thought this was due to really hard/cheap pads glazing my rotors. I went to the store and bought some Wagners Semi-Metallic pads. I also took off my rotors and resurfaced them with one of those plastic polishing wheels and drill. The rotors looked great when I put them back on, and indeed, the stopping felt more... fluid. But the brakes still suck. I can stand on them, and I KNOW in my heart of hearts that it should stop better than that. My 91 Eclipse with no ABS had shorter stopping distance.

I'm starting to think I have a vacuum leak or a bad brake booster. It doesn't feel like the pedal is going down to the floor... Going to bleed all the calipers today, but I don't think that's going to solve it.

Any suggestions?

 

[IDoSeaDoo]

Do TDI's have a vacuum pump?

How does a TDI even build vacuum? With the turbo and all, is there enough manifold vacuum to engage the brake booster? I know turbos only have pos. mani pressure on acceleration, but would a manifold/vacuum leak be causing this?

 

[Got Bearings?]

You probably have a vacuum leak. TDIs have a vacuum pump on the drivers side of the head. From the brake booster, there is a hard plastic line going to the vac pump. Inspect the plastic line and the rubber hose attached to it. I've had the rubber hose break and I slipped on the remaining hose to the pump along with a hose clamp and it's fine.

 

[IDoSeaDoo]

Inspect Brake Booster Hose

Thanks Bearings, can't wait to get home and check it out. I hope like hell that's it. My last PD TDI had great brakes, I hope that's all it is with this one.

 

[BobnOH]

Often these cars show some problems with vacuum supply to the power boost reservoir. But, it should still stop hard when you stand on it, the pedal will be very stiff.
I think your problem may be something hanging, like a caliper, slide pins or even stuck e-brake. That or the hydraulics, have you done a full flush and bleed ever?

 

[IDoSeaDoo]

Haven't done full bleed.

I'll do that today, but it almost feels like I have no power brakes. I stand on it, and it's as if my weight is not enough. I feel like I'm maxing it out and it just slides... It doesn't feel spongy, rather very stiff and inadequate.

Here's a curious thing, when I shut the car off, the pedal forces my foot up. It doesn't feel right, I don't think my old jetta did that. Could that be the air leaking back into the brake booster?

 

[BobnOH]

I'll do that today, but it almost feels like I have no power brakes. I stand on it, and it's as if my weight is not enough. I feel like I'm maxing it out and it just slides... It doesn't feel spongy, rather very stiff and inadequate.

Here's a curious thing, when I shut the car off, the pedal forces my foot up. It doesn't feel right, I don't think my old jetta did that. Could that be the air leaking back into the brake booster?

yea, that sounds like the vacuum pipe. Over by the vac pump, there's a plastic connector that the hose connects too. They will swivel for some reason, but it's a likely spot for leaks

 

[IDoSeaDoo]

Thanks Bob, I'll def. check that out today.

 

[PDJetta]

I had the same problem a few months back on my '04. Turns out that the hard plastic vacuum line from the vacuum pump to the brake booster had a small crack on the underside where the tight bend is. I only found it by running my fingernail over it. The pipe bend held the crack closed.

I too thought it was glazed brake pads. Light brake application, no problem. Hard brake application was scary.

The replacement line IS DIFFERENT than the one used on the ALH engine (I got the ALH one by mistake first go at it). The one for the BEW is:

1J0-612-041-FD.

Its about double the cost of the ALH line. I bought mine at 1stvwparts.com for $50 plus $10 shipping (my local dealer wanted $95 for it and it was special order, come in and prepay first).

Take a close look at the brake booster line and use a mirror to check the underside. Good chance that is your problem.

The bend on the line for the BEW is tighter than the line for the ALH, so I would suspect this line will fail more frequently. The brake booster line on my mother's 2000 Jetta TDI is still fine. Go figure!

--Nate

 

[IDoSeaDoo]

Resolution

Well, you guys nailed it. I pulled off the hose and there was a gnarly crack with even a hole in it. 10 seconds of taping with electrical tape got it fixed for now. Will be putting a solid rubber hose on it in the AM. Thanks Guys!

Job done

 

[oswegoPD]

I just found the same problem on my 2004 Jetta. Thanks PDJetta

 

[FanmaN3]

thanks for the advice, My daughter's 02 golf had same issue. replaced the plastic line with some thick wall Vac booster rubber hose, i had salvaged from somewhere and the problem is gone!!!