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Strange noise after shut-off

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passat_0115

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Discussion starter · #1 ·
01 AWM

I'm not sure if it was always making this sound or not.... I certainly don't remember it. It's a humming/buzzing sound.... fairly low pitched, but loud enough that you could hear it 20 or so feet away from the car with the hood closed. It is not a clicking sound (as I recall there is a part there that clicks when its working... it's not that piece). It's definitely coming from the airbox area. The sound happens every time the car is shutoff when the engine is hot (not sure about cold... don't usually shut the car off when its still cold but will try in the morning) and lasts about 2 or three seconds. The sound could be happening when the car is running as well and it seems like it might be but it's too difficult to say for sure over the noise of the running engine.

No CELs and the car runs great. No other noises or problems.
 
#2 ·
passat_0115 said:
01 AWM

I'm not sure if it was always making this sound or not.... I certainly don't remember it. It's a humming/buzzing sound.... fairly low pitched, but loud enough that you could hear it 20 or so feet away from the car with the hood closed. It is not a clicking sound (as I recall there is a part there that clicks when its working... it's not that piece). It's definitely coming from the airbox area. The sound happens every time the car is shutoff when the engine is hot (not sure about cold... don't usually shut the car off when its still cold but will try in the morning) and lasts about 2 or three seconds. The sound could be happening when the car is running as well and it seems like it might be but it's too difficult to say for sure over the noise of the running engine.

No CELs and the car runs great. No other noises or problems.
Click to expand...
normal.its the secondary waterpump circulating coolant thru the aluminum heads/ engine ,both my
V-6 passats do that when hot /shut down..always have
/sleep well
 
#3 ·
passat_0115 said:
01 AWM

I'm not sure if it was always making this sound or not.... I certainly don't remember it. It's a humming/buzzing sound.... fairly low pitched, but loud enough that you could hear it 20 or so feet away from the car with the hood closed. It is not a clicking sound (as I recall there is a part there that clicks when its working... it's not that piece). It's definitely coming from the airbox area. The sound happens every time the car is shutoff when the engine is hot (not sure about cold... don't usually shut the car off when its still cold but will try in the morning) and lasts about 2 or three seconds. The sound could be happening when the car is running as well and it seems like it might be but it's too difficult to say for sure over the noise of the running engine.

No CELs and the car runs great. No other noises or problems.
Click to expand...
normal.its the secondary waterpump circulating coolant thru the aluminum heads/ engine ,both my
V-6 passats do that when hot /shut down..always have,but it lasts appx 1-2 mins if thats the samr noise you mean
 
#8 ·
When I had the same sound in my 1.8T in the same air box area, it was the wastegate flap inside the turbo. It breaks after a while and remains open permenatly, thus causing air to pass through it and creating that sound. I installed a new KO3 since it happened to me. Sure enough, the sound went away after the new turbo was installed.

Image
 
#9 ·
Strangely enough, it is probably your PCV bleeder valve. There is a storage tank for vacuum which, when you shut down, is still equalizing and pulling air through the PCV. They make noise, to a greater or lesser extent, and that noise travels down the metal pipe/puck valve/etc to the airbox.

I replaced my PCV valve, while in there for other components (pipe, T, suction pump) a while back. The replacement one was so noisy that it sounded like a party horn. I could hear it even when the engine was running. Got another one, still a bit noisy, so I ended up putting the original back in.

Try this: while the engine is running, pinch off the hose that goes to the PCV bleeder valve. You can do this with your thumb/forefinger or maybe a pair of pliers. I bet you will be able to hear a decrease in humming noise. You could also have someone else shut down the engine while you pinch that hose, and there will be no noise.

The good news is that you have audio confirmation that your PCV bleeder valve is not clogged.

VW kept changing this arrangement slightly from model to model. In my AUG, the bleeder is sucked by the suction pump; in your AWM the vacuum seems to come from somewhere else, and the suction pump routes elsewhere (just from the diagrams).

OTOH, it could be something else, like an arcing flux capacitor.
 
#11 ·
passat_0115 said:
01 AWM

I'm not sure if it was always making this sound or not.... I certainly don't remember it. It's a humming/buzzing sound.... fairly low pitched, but loud enough that you could hear it 20 or so feet away from the car with the hood closed. It is not a clicking sound (as I recall there is a part there that clicks when its working... it's not that piece). It's definitely coming from the airbox area. The sound happens every time the car is shutoff when the engine is hot (not sure about cold... don't usually shut the car off when its still cold but will try in the morning) and lasts about 2 or three seconds. The sound could be happening when the car is running as well and it seems like it might be but it's too difficult to say for sure over the noise of the running engine.

No CELs and the car runs great. No other noises or problems.
Click to expand...
Did you ever figure out what the noise was? I recently changed my jet pump for the PCV system and now I am hearing that noise at shut off and to some extent when it is running. If it is the due to the bleeder valve it is sure traveling a long ways since the bleeder is on the opposite side of the engine.
 
#12 ·
JTL said:
Did you ever figure out what the noise was? I recently changed my jet pump for the PCV system and now I am hearing that noise at shut off and to some extent when it is running. If it is the due to the bleeder valve it is sure traveling a long ways since the bleeder is on the opposite side of the engine.
Click to expand...
If you got the noise when you replaced a (clogged) suction pump, then it is likely the bleeder valve. Pinch off the hose going to the bleeder and see whether the noise changes.

I first got the noticeable noise when I replaced the original bleeder (and suction pump). I ended up putting back in the original bleeder, which still worked fine and wasn't as noisy. I ordered another bleeder, from another distributor, and it also hummed a bit - more than original but not as much as the first replacement.
 
#13 ·
I had the bleeder valve out because I also replaced the breather tube. I could easily blow through it one way, the same with the check valves. Now I wonder if I never heard it before because the jet pump was clogged masked the noise. I am not sure that i can pinch anything off. The valve body is in the large 3-way connection and the other end goes up to the jet pump and it is pretty thick rubber. I suppose I could remove it from the jet pump and put my finger over it.
 
#14 ·
Update.
It appears to be a noise emanating from the puck valve. sort of like a weak fog horn for a couple of seconds. I did have that off and cleaned it when I did the rest of the stuff. The other thing that I have noticed since I replaced the jet suction pump is that my oil leak has almost disappeared. I have the VCG and the CCT seal and may replace them at some point but now it is hardly worth the effort.
 
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