Hard Brake Pedal

jwebb335xi · 11-09-2017, 01:59 PM

Hey guys,

I have replaced the gasket/grommet between brake booster and check valve pipe and that fixed the hard brake pedal for a few months. Then, i replaced both grommet and check valve. Again, Issue was fixed for a few months. Then, I did blue Gasket Maker to seal the grommet. And, again, the issue was resolved, but only for a few days.

Wednesday morning I installed a new grommet and new check valve. The car sat outside on purpose last night (roughly 35*), and the brake pedal was not stiff like it had been.

I wonder whether I should just expect to replace that damned grommet and check valve every year!?!!

Is this issue very common??

Could there also be a leak in the booster itself or in the gasket sealing master cylinder to booster or booster to firewall? Both would seem extraordinary.....

juld0zer · 11-11-2017, 07:36 AM

Did you use genuine BMW grommets or the ATE OEM version?

Does your vacuum line sit properly in the firewall grommet?

jwebb335xi · 11-12-2017, 10:54 AM

Quote:

Originally Posted by juld0zer

Did you use genuine BMW grommets or the ATE OEM version?

Does your vacuum line sit properly in the firewall grommet?

All good questions. New vacuum with check valve purchased at the dealer last week. Installed and sitting properly. No problems thus far!

PhaseP · 11-14-2017, 01:44 AM

You may have a leak somewhere else and each time you change the grommet or line you maybe reseating in the process wherever else is leaking to hold for a while the vacuum.

I had leak on the grommet and years back had replaced grommet and line using gasket maker on the seal groove it had fixed it and it is still good.

There was a post suggesting by pro (Fureur?, sorry my typo) that the o-ring between brake booster and the master cylinder also leaks sometimes.

If not those it could be your vacuum booster itself, assuming the check valve on the tube and the grommet seal is good.

jwebb335xi · 11-14-2017, 12:40 PM

Quote:

Originally Posted by PhaseP

You may have a leak somewhere else and each time you change the grommet or line you maybe reseating in the process wherever else is leaking to hold for a while the vacuum.

I had leak on the grommet and years back had replaced grommet and line using gasket maker on the seal groove it had fixed it and it is still good.

There was a post suggesting by pro (Fureur?, sorry my typo) that the o-ring between brake booster and the master cylinder also leaks sometimes.

If not those it could be your vacuum booster itself, assuming the check valve on the tube and the grommet seal is good.

The car sat for over two days; no vacuum loss. Brake pedal was "normal" at start-up this AM!!! Maybe I got it.

juld0zer · 11-19-2017, 01:22 AM

Were the old grommets OEM or purchased from a dealer each time?

PhaseP · 11-19-2017, 03:41 PM

I had bought BMW branded grommet online though, most probably ECS tuning, but came with a BMW bag and sticker. There wasn't any other option anyway at that time only BMW.

2002 · 01-28-2019, 05:48 PM

A couple of weeks ago I had the EGR valve heater recall done at the local stealer on my 2009 328i e92 (SULEV). Next morning the brake pedal was rock hard. I read about your solutions of the brake booster gasket above, so changed it by removing the DCS after a brake fluid extraction. I put a thin film of silicone grease on the gasket, as described above, mated the check valve, put the DCS back in, and bled the brakes. The next morning the brake pedal was a little hard, but tolerable. During the next week it was apparent that the gasket change had not solved the issue. Over this last weekend I removed the alternator (had to buy a new set of aluminum bolts), and replaced the vacuum line attached to the pump. I tested the old line and it appeared to be OK, but while I was there I went ahead and replaced line with a new one. Before inserting the vacuum line into the pump I coated the internal diameter of the pump flange with a thin film of silicone grease, also doing the same to the opposite end of the vacuum line, reinstalled the alternator, and connected all of the vacuum line pieces. Yesterday morning and this morning the brake pedal acted normal, as before the stealer work. I think the work done in replacing the EGR valve heater somehow broke the seal between the vacuum line and the vacuum pump. Anyway all is good now, and I didn't have to fight with the stealer for the $55 worth of parts I got from FCPEuro. Thanks for your help here and suggestions.

juld0zer · 02-05-2019, 06:51 AM

The check valve should prevent loss of vacuum in the servo once the engine is switched off. There is another check valve on the pump connection but that shouldn't cause the servo's check valve to stick open.

Perhapa you have a sticky check valve?

11-09-2017, 01:59 PM	#1
jwebb335xi Major 207 Rep 1,070 Posts Drives: 2008 335 XI Join Date: Jun 2014 Location: Chicago Burbs iTrader: (0)	Hard Brake Pedal - Again Hey guys, I have replaced the gasket/grommet between brake booster and check valve pipe and that fixed the hard brake pedal for a few months. Then, i replaced both grommet and check valve. Again, Issue was fixed for a few months. Then, I did blue Gasket Maker to seal the grommet. And, again, the issue was resolved, but only for a few days. Wednesday morning I installed a new grommet and new check valve. The car sat outside on purpose last night (roughly 35*), and the brake pedal was not stiff like it had been. I wonder whether I should just expect to replace that damned grommet and check valve every year!?!! Is this issue very common?? Could there also be a leak in the booster itself or in the gasket sealing master cylinder to booster or booster to firewall? Both would seem extraordinary..... __________________ JWebb335xi MHD / Wedge / 93 Octane/ xHP / FMIC / Inlets / Catted DPs / CP / DVs
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11-11-2017, 07:36 AM	#2
juld0zer Lieutenant Colonel 480 Rep 1,600 Posts Drives: Prev 135i 7DCT, Now 130i 6sp Join Date: Jul 2016 Location: 2153 iTrader: (0)	Did you use genuine BMW grommets or the ATE OEM version? Does your vacuum line sit properly in the firewall grommet?
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11-14-2017, 01:44 AM	#4
PhaseP Colonel 1034 Rep 2,113 Posts Drives: 325XI Join Date: May 2010 Location: Earth iTrader: (0)	You may have a leak somewhere else and each time you change the grommet or line you maybe reseating in the process wherever else is leaking to hold for a while the vacuum. I had leak on the grommet and years back had replaced grommet and line using gasket maker on the seal groove it had fixed it and it is still good. There was a post suggesting by pro (Fureur?, sorry my typo) that the o-ring between brake booster and the master cylinder also leaks sometimes. If not those it could be your vacuum booster itself, assuming the check valve on the tube and the grommet seal is good.
	Appreciate 2 jwebb335xi207.00 Quote

11-19-2017, 01:22 AM	#6
juld0zer Lieutenant Colonel 480 Rep 1,600 Posts Drives: Prev 135i 7DCT, Now 130i 6sp Join Date: Jul 2016 Location: 2153 iTrader: (0)	Were the old grommets OEM or purchased from a dealer each time?
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11-19-2017, 03:41 PM	#7
PhaseP Colonel 1034 Rep 2,113 Posts Drives: 325XI Join Date: May 2010 Location: Earth iTrader: (0)	I had bought BMW branded grommet online though, most probably ECS tuning, but came with a BMW bag and sticker. There wasn't any other option anyway at that time only BMW.
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01-28-2019, 05:48 PM	#8
2002 Private 21 Rep 79 Posts Drives: 2009 BMW 328i E92 Coupé Join Date: Oct 2012 Location: Santa Rosa, CA iTrader: (0)	A couple of weeks ago I had the EGR valve heater recall done at the local stealer on my 2009 328i e92 (SULEV). Next morning the brake pedal was rock hard. I read about your solutions of the brake booster gasket above, so changed it by removing the DCS after a brake fluid extraction. I put a thin film of silicone grease on the gasket, as described above, mated the check valve, put the DCS back in, and bled the brakes. The next morning the brake pedal was a little hard, but tolerable. During the next week it was apparent that the gasket change had not solved the issue. Over this last weekend I removed the alternator (had to buy a new set of aluminum bolts), and replaced the vacuum line attached to the pump. I tested the old line and it appeared to be OK, but while I was there I went ahead and replaced line with a new one. Before inserting the vacuum line into the pump I coated the internal diameter of the pump flange with a thin film of silicone grease, also doing the same to the opposite end of the vacuum line, reinstalled the alternator, and connected all of the vacuum line pieces. Yesterday morning and this morning the brake pedal acted normal, as before the stealer work. I think the work done in replacing the EGR valve heater somehow broke the seal between the vacuum line and the vacuum pump. Anyway all is good now, and I didn't have to fight with the stealer for the $55 worth of parts I got from FCPEuro. Thanks for your help here and suggestions.
	Appreciate 1 Quote

02-05-2019, 06:51 AM	#9
juld0zer Lieutenant Colonel 480 Rep 1,600 Posts Drives: Prev 135i 7DCT, Now 130i 6sp Join Date: Jul 2016 Location: 2153 iTrader: (0)	The check valve should prevent loss of vacuum in the servo once the engine is switched off. There is another check valve on the pump connection but that shouldn't cause the servo's check valve to stick open. Perhapa you have a sticky check valve?
	Appreciate 0 Quote