Bufetting sound and vibration above 40mph

[timfanelli01]

So my 2004 Jetta w/ 2.0L engine has been making a strange buffetting sound when it gets above 40MPH... I suspected something in the drivetrain -- I've recently done new control arms and bushings, axles, upper strut mounts and bearings, all 3 engine mounts, and passenger side wheel bearing which was grinding. I just had my mechanic recheck everything, and I was suspicious of the driver side wheel bearing -- but they say it's the engine.

They've been going over it with a fine toothed come, and have isolated the sound to the engine. I don't hear it while not moving (ie, revving in the driveway), so I guess I'm more suspicious of the transmission?

Anyone have any thoughts or experienced this before? I'm at a loss.

[ps2375]

Are your wheelwell liners fastened in place?Those are known to have screws missing/torn and flap in the wind. If one or both has a "v" notch cut into it, that means it has been rubbing on the tire.

[timfanelli01]

hmm - I'll check that out. The car is still at the shop - I just went down and took my mechanic for a drive... he was definitely looking into a different noise than the "buffetting" I described. He's going to go over the drivetrain with a fine toothed comb, retorque everything, and rotate+balance and take it out again.

In the meantime, the noise he *though* I was describing in a harmonic vibration from the engine at ~3,500 RPM. It makes a loud tone, and vibrates through the entire chassis... he asked if these engines have a balance shaft which may have broken, but I have no idea -- any input there?

Thanks!

[ps2375]

no balance shaft. You might look into another mechanic that has slightly more knowledge of VW's. Unless you are happy with this one.

[timfanelli01]

no balance shaft. You might look into another mechanic that has slightly more knowledge of VW's. Unless you are happy with this one.

My mechanic actually suggested the same thing. We're going to leave the engine noise alone for now, and just chase down the drivetrain noise -- he's not comfortable diagnosing it, so I'll bring it to a VW guy I know (my favorite part about these guys is they know when they're out of their element, and don't mess around if they don't know what they're doing)

[ps2375]

Most won't do that, they just want your money.

[Anony00GT]

Most won't do that, they just want your money.

I wouldn't say that. I know several shops, albeit they are larger shops, that regularly do this. They make their money on basic repairs (tires, brakes, tune-ups, etc), and when a diagnostic challenge comes in, they almost automatically punt.....

....and the car lands right in my shop

But yes, this mechanic is doing the right thing IMO. Get someone who knows VW's to look into it. It's also very hard for us to diagnose noises on an internet forum.