After car is shut off, I have a groan/vibration coming from drivers floorboard....

josh8loop

Veteran Member
Joined
Sep 15, 2009
Location
Vero Beach, Fl.
TDI
2002 VW Jetta TDI Manual(performed 01M to 5-speed swap) - 183,000 miles and climbing!
Fellas,

As the title suggests, after the car is shut off, I have a groan/vibration coming from the drivers side footwell/fire wall area. I notice it when I shut the car off, and remain seated in the car for a little while gathering my stuff. It subsides after 10 seconds or so. Seems like it could be vacuum system related-perhaps a damaged check valve or damaged vac brake booster. Anyone have any experience with this? Thanks!
 
T

tyrone shoelaces

Guest
push down the brake pedal while engine is running, remember how hard it is to push down, shut off your car, wait for it to make the sound and subside, then try pressing the brake pedal again, is it harder to press down then while the engine is running? if so then it is most likely your booster or a line to it is leaking and not holding the vaccum in, it is a standard when manufacturing vehicles that the booster should be able to hold enough of a vaccum so that if your engine was to stall that you should be able to get three to four good braking events out of the vehicle with the engine off, and the boosters are supposed to hold a vaccum for X amount of minutes without losing the vaccum it has stored.

Tyrell
 

josh8loop

Veteran Member
Joined
Sep 15, 2009
Location
Vero Beach, Fl.
TDI
2002 VW Jetta TDI Manual(performed 01M to 5-speed swap) - 183,000 miles and climbing!
push down the brake pedal while engine is running, remember how hard it is to push down, shut off your car, wait for it to make the sound and subside, then try pressing the brake pedal again, is it harder to press down then while the engine is running? if so then it is most likely your booster or a line to it is leaking and not holding the vaccum in, it is a standard when manufacturing vehicles that the booster should be able to hold enough of a vaccum so that if your engine was to stall that you should be able to get three to four good braking events out of the vehicle with the engine off, and the boosters are supposed to hold a vaccum for X amount of minutes without losing the vaccum it has stored.

Tyrell


It seems as though I can pump the brake a good four or five times after the car is shut off, and I still have vacuum brake assist. After the vacuum bleeds off, the brake pedal once again gets hard as expected. I know my vacuum system regarding vacuum lines and all is good. I have in the past replaced all the lines, resealed the vacuum pump outlet nipple, and repaired/replaced larger lines going to the brake booster. Only question now is if the vacuum check valve is having issues and oscillating intermittently when the system bleeds down. I will have to monitor things over time to come to a conclusion on this. I will give updates as I get new info.

..
 

josh8loop

Veteran Member
Joined
Sep 15, 2009
Location
Vero Beach, Fl.
TDI
2002 VW Jetta TDI Manual(performed 01M to 5-speed swap) - 183,000 miles and climbing!
does the groan- vibration change in pitch or intensity when you step on the brake pedal ?

Well, never though to check that when it was happening. That is a good idea, and one I hope to look into soon. Although it is somewhat intermittent and hard to catch.
 
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