# Help!! Vw golf mk4 bad brake issues



## kristian18t (Jun 26, 2015)

Hello guys!
I'm new to this forum but I have some major brake issues and can't solve them for almost an year. I'll be quite short with my problem (as I can).
I drive a VW Golf mk4 1.8T with AGU engine. The car is with stock internals but is running a TD05-16g turbo setup.

The brake pedal started to feel really spongy (it feels like the system has air in it). It happened instantly. I couldn't stop for a very short distance with very low speed, so I got concerned and besides I don't want to get killed.......
No brake faults with VAG-COM

I have a very long pedal travel, with no intensions of stopping. It starts stopping at the very bottom of it's travel, but then abs kicks in and makes it worse.

I've tried bleeding the system the old fashion way with a mate. No changes.... So I've decied to change parts one by one:

Changed the brake fluid - bled, no result
Master Cylinder - bled, no result
ABS Pump - bled with VAG-COM and by hand a couple of times, no result
New TRW Brake Liens - bled and still no result
Took also the calipers off for a look. They seem fine to me. 
Made a couple of tests of the brake booster, it seems fine. My car doesn't have rough idle nor is changing vaccuum, so I don't think it's causing it.. 

Now I'm desperate..
Please give me some hints!!

Thanks,
Kris


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## GasInMyVeins (Jul 11, 2010)

Are you ever having to top off the fluid? Kind of sounds like a leak, if you've bled everything so thoroughly.


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## kristian18t (Jun 26, 2015)

Thanks for responding!
I haven't lost any fluid at all... What is the easiest way to find a leak? Any other suggestions?


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## genixia (Feb 8, 2002)

Check for broken pcv system check valve allowing boost pressure where you should have vacuum. 

Sent from my SAMSUNG-SM-G900A using Tapatalk


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## kristian18t (Jun 26, 2015)

Hi,
Thanks for your reply! 
Today I took off my entire oil crank ventilation system and noticed:
The valve which is under my intake manifold and leads with a rubber hose to my intake, flows in both ways (which means that it has gone bad, since it's a one way valve). 
I think I'm going to make a new DIY oil vent system, eliminating the valve, since it's very expensive at my local VW dealer. Has someone already done this?
Just hope my brakes will get back eventually.


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## GasInMyVeins (Jul 11, 2010)

Please post a picture of the valve in question (I long ago deleted all my emissions stuff and simplified vac, so I can't go look at where you described).

You still need to have a check valve in the line to the brake booster though, so I think your plan may not work.


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## kristian18t (Jun 26, 2015)

Hi,
The valve that is connected to the brake booster is not involved in this process. I will upload some pics later today.


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## dogdog (Jul 26, 2007)

Bleed those brakes in proper sequences ?

Not sure about the "sudden" spongy brake.... and not sure if abs pump sequencing is replacing brake bleeding ? 
Maybe you have a newer car..... that self bleeds.

at least when I change my brake lines.... those "performances" lines. I had to bleed 3x or 4x in the sequences they recommend in the manual... which is either farthest line to closest line or closest line to the furthest line..... dependent on which type master cylinder you have.... but will say which sequence in your manual.

I am curious how is the PCV hose/valves have anything to do with your brakes being spongy?

You brakes should work with or without the engine running... think that is a safety standard. unless you have a defective brake component. such as master cylinder or leak in the brake line , air in systems etc.


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## maximizese (Jun 8, 2004)

dogdog said:


> Bleed those brakes in proper sequences ?
> 
> Not sure about the "sudden" spongy brake.... and not sure if abs pump sequencing is replacing brake bleeding ?
> Maybe you have a newer car..... that self bleeds.
> ...


I believe the PCV is related to the vacuum pump that runs to the brake booster. I've had a softer brake pedal for the last 10 years/150K miles but mine is not nearly as bad as the OP. My brakes feel linear, but with less power and a tad more travel than when everything was fine. When I had my TDI smogged, the tech mentioned that my PCV valve looked to be seeping a little oil. I'm going to replace it and cross my fingers. I've already determined that my brake booster, MC, calipers, lines, and vacuum pump aren't the issue.


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## dogdog (Jul 26, 2007)

maximizese said:


> I believe the PCV is related to the vacuum pump that runs to the brake booster. I've had a softer brake pedal for the last 10 years/150K miles but mine is not nearly as bad as the OP. My brakes feel linear, but with less power and a tad more travel than when everything was fine. When I had my TDI smogged, the tech mentioned that my PCV valve looked to be seeping a little oil. I'm going to replace it and cross my fingers. I've already determined that my brake booster, MC, calipers, lines, and vacuum pump aren't the issue.


..... the brake should operate and stops the car with or without the engine running. if it is spongy when the engine is off.. bleed the line or troubleshoot the master cylinder.
I usually just have the engine off.. 4 wheel jacked , some one pump and hold the brake if I am able to rotate the wheels by hand, there is air in the system or something is wrong.... PCV / brake booster not even in play at this point. Especially if OP says he changed the brake hose. Proper bleeding is required when ever there is a chance of air introduce into the system.


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## Kamikazee (Apr 20, 2013)

Hi, there!
I would check the feel of the brake before and after turning on the engine. If the sponginess is not present when engine off then the hydraulic part of the brake system is ok. If it is, then the brake booster assy is the culprit. Let us know what you find! Good luck.


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## autobahn1.8t (Jun 9, 2005)

I have this same issue..

Car brakes fine but at the final 10-5 mph, the abs kicks in and it feels / sounds like a grinding issue happening..

Now I recently broke a break line and had it replaced so I feel like it has to do with that some how. I just haven't had the time to look at it.


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## GasInMyVeins (Jul 11, 2010)

autobahn1.8t said:


> I have this same issue..
> 
> Car brakes fine but at the final 10-5 mph, the abs kicks in and it feels / sounds like a grinding issue happening..
> 
> Now I recently broke a break line and had it replaced so I feel like it has to do with that some how. I just haven't had the time to look at it.


I don't think your issue is the same. I had the exact same issue on my wife's Beetle and it was one bad wheel speed sensor.


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## Mr.AC (Nov 24, 2014)

If your break peddle is going to the floor before the breaks engage you have a major problem. If you have bled every thing and you still have poor braking performance and your brake fluid level is not going down and your 100% sure there is no leaks and air in the system your master cylinder is bypassing internally and you only have half your brakes working. You need to replace it. I'm not sure by reading your post if you have replaced it or just tried to bleed the air out there. If you did replace your master cylinder did you bench bleed it before you installed it? If you didn't and just tried to bleed it like you would if your replaced a brake line then you have air trapped in your master cylinder. The only way your going to get the air out is by beach bleeding it. Then you have to bleed the entire braking system again to get all the air out. 

As far as your abs coming on that's more then likely a separate issue. If it coming on when your at low speed your more then likely have a bad wheel speed sensor. You will need a scanner to diagnose where the problem sensor is. That will not always throw a code or a mel light.


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## drscott (Jun 13, 2015)

*Bleeding Brake System*

The Bentley manual states on 47-14 that the sequence for bleeding the brakes for ITT Mark 20 IE systems. I have a 2000 GTI 1.8. 

right rear caliper
Left rear caliper
Right Front caliper
Left front caliper 

on ITT Mark 60 IE systems 

Left front caliper 
Right Front caliper
Left rear caliper
Right rear caliper


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