1977 Westfalia - Buzzing Noise -Vibration

[mattg]

OK - now lets play name that noise. In 2nd and 3rd gear as I accelerate I notice a weird buzz that will last for about a second or two and then goes away as I continue to accelerate in gear. It seems to be some type of vibration that is coming from the rear of the vehicle - on the inside - perhaps on the right rear. As I stick my head out the window while I am driving the sound does not seem to be coming from outside. I have looked around inside and have not found anything that is rattling. The vibration happens at higher rpms and is not at all audible at idle. Any ideas? I would like to rule out any major issues - The bus starts, stops and continues to run fine. I have yet to hear the noise in 1st or 4th gear even as I was cruising at 65 yesterday.

[mattg]

I checked a few things today - read some older posts and still am unclear where the noise is coming from. I can reproduce the sound when I give it gas in gear. I cannot reproduce the sound out of gear. Is there a sound that the fuel pump gives when it is on its last leg. The bus does not hesitate under load. I am stumped and driving the family crazy. How about the transmission - does it ever make a buzzing, whirling sound only under load - the bus stays in gear and does not seem to have any signs of transmission trouble. Ramblin on - winter is approaching. Only a few more weeks until it is parked in the garage and this noise takes a break only to reappear in the spring.

[Sluggo]

Had that happen on mine and changing out the tranny fluid with Redline MT90 got it 1/2 way eliminated. Refurbishing the clutch cable, pedal and connections got it the rest of the way. Mine was a whirring noise only while in motion. Usually in 2nd. I think it was the whir of the gears vibrating through the cable.

[Amskeptic]

I checked a few things today - read some older posts and still am unclear where the noise is coming from. I can reproduce the sound when I give it gas in gear. I cannot reproduce the sound out of gear. Is there a sound that the fuel pump gives when it is on its last leg. The bus does not hesitate under load. I am stumped and driving the family crazy. How about the transmission - does it ever make a buzzing, whirling sound only under load - the bus stays in gear and does not seem to have any signs of transmission trouble. Ramblin on - winter is approaching. Only a few more weeks until it is parked in the garage and this noise takes a break only to reappear in the spring.

Imagine that the engine/transaxle combination twists a little under load and the heater control valve on the right is vibrating against the bell housing carrier support, or something like that.
Colin

[Manfred]

Maybe a loose tin?

[Robert]

Sounds like a sympathetic viberation.
Bob

[mattg]

Had that happen on mine and changing out the tranny fluid with Redline MT90 got it 1/2 way eliminated. Refurbishing the clutch cable, pedal and connections got it the rest of the way. Mine was a whirring noise only while in motion. Usually in 2nd. I think it was the whir of the gears vibrating through the cable.

Was it a buzzing noise? This noise kinda sounds like a buzzer if you were to remove the keys without turning the lights out kinda thing...

[mattg]

I checked a few things today - read some older posts and still am unclear where the noise is coming from. I can reproduce the sound when I give it gas in gear. I cannot reproduce the sound out of gear. Is there a sound that the fuel pump gives when it is on its last leg. The bus does not hesitate under load. I am stumped and driving the family crazy. How about the transmission - does it ever make a buzzing, whirling sound only under load - the bus stays in gear and does not seem to have any signs of transmission trouble. Ramblin on - winter is approaching. Only a few more weeks until it is parked in the garage and this noise takes a break only to reappear in the spring.

Imagine that the engine/transaxle combination twists a little under load and the heater control valve on the right is vibrating against the bell housing carrier support, or something like that.
Colin

What are you saying - should I check the heater control valve? I am very good at imagining - not so good with diagnosing unknown noises - all of sudden I hear a voice - do you hear that voice. You know what I'm saying.

[mattg]

I think if I have the wife sit in the back she can help me determine where the noise is originating from. Only problem is getting out for a quick ride with 3 kids 5 and under. Perhaps she can narrow down the source of my unknown noise.

[AzironaZack]

My guess is that you're missing a bushing on the torque tube for your shifter and that the tube is vibrating inside of the tube that it runs through to get to the transmission.

I only guess that because I've had that trouble myself. It was annoying and it only occurred within a narrow range of engine RPM (I guess it must have been some sort of harmonic frequency).

[mattg]

My guess is that you're missing a bushing on the torque tube for your shifter and that the tube is vibrating inside of the tube that it runs through to get to the transmission.

I only guess that because I've had that trouble myself. It was annoying and it only occurred within a narrow range of engine RPM (I guess it must have been some sort of harmonic frequency).

I will check it out and see if this corrects the noise. Hopefully this weekend I will have my wife in the back to determine the exact origin of the noise. I will report back with any findings.

[vwlover77]

Check to see if the outer sheet metal on your heater boxes is vibrating against the inner core. Give them a rap with the palm of your hand to see if any strange vibrations result. Also check where the fresh air pipes route through the tin. Anything rubbing or loose?