2002 Volkswagen Beetle Repair Question
Volkswagen Beetle Noise Problem
The only way to find the source of any noise, is the follow the sound to the source with the ear.
I have not run into such a noise, aside from turbo spool, throttle body whistle, radiator fan squeal, suspension bushing squeaks, starter pinion etc.
Did any of the people looking at the vehicle actually hear the noise? Record the noise with your cellphone / video camera and follow it to
as close to the source as you can.
Is it louder "in the car" or "under the hood"?
Sorry... post the video on youtube (free) and then post the link here so that we can listen to the noise.
Thank you for your reply, Thomas. I recorded the sound back when it first happened end of August 2012. It's not a video though. It's hard to film it while driving the car :-) hope it works! . While going through my records to find this sound file, I realized that this issue started to happen right after the seat belt buckle and door latch were replaced. I recorded the sound back then to send it to the mechanic that worked on the seat belt buckle and door latch but when he checked the car, he said, the noise cannot be related to the fixes he made...
Anyway, hope this helps! In this sound file noise is really short but that's not always the case. Sometimes it can go on for almost 20-30 seconds, which is very annoying.
Wow, that is a weird and annoying sound!
Any aftermarket boost gauges in the car?
I really don't know... It's an 11 year old car and I honestly don't remember if any boost gauge was replaced or not and if it is aftermarket or not :-(
Does the car need to be driven for the noise to occur, or can it be replicated by just revving the engine while parked?
Obviously if it needs to be driven, it may be harder to find, since one can not look and drive at the same time.
It does sound like an air / vacuum / boost leak and not an electrical component issue (relay).
The brake booster and valves were a good starting point... I would not know what to guess at this point.
If I ever run into a similar noise, I will post here with the fix!
No, the car doesn't need to be driven for the noise to occur. It occurs at any of these situations:
1) car is parked, start the engine, noise comes on
2) or noise comes on randomly any time during driving. Doesn't matter if you are turning, or braking, or speeding, or cruising. Could happen any time
3) car is driven but *just* parked and engine *just* stopped, noise can sometimes continue for another 10-20 seconds
So, any of the situations above could happen. Even all of them could happen during one single ride. This is why it is so frustrating. It is just so hard to pinpoint the problem.
Thank you for your help so far, I appreciate it! Yeah I hope someday someone figures out this issue and posts the fix here :-)
The brake booster is supposed to "retain / store" vacuum after the engine is shut off.
There is a check valve that in the engine bay by the booster, that is supposed to be closed when the engine is off, that is supposed to prevent
the vacuum from leaving the booster and enter the engine.
Atmospheric pressure can enter the booster on the brake pedal side.
Something is probably not right with that part of the system, hence the booster and valve replacement (logical place to start).
Have him re-check the system, smoke test the vacuum system and the booster.
If it is automatic, there may also be a an electrical "vacuum pump" that assists in providing enough vacuum to the booster... which should be checked.
In that case, also, vacuum and pump operation can be checked with a scan tool via the ABS Module.
Diagnosis from the dealer (with their exact words on the report): "found suction jet pump check valve bad, causing turbo boost to leak into brake booster. Recommend replacing check valve and brake booster"