engine vibration at 3500 and above

[mech]

I just bought a 91 tsi talon and the engine has a violent vibration when rpm's are at 3500 and above, no vibration at all when below 3500. I can see that the transmission was changed because of the writing on the case. When I raise the hood and rev the engine I can see the engine vibrating. the car runs well other than the vibration.

 

[Spicyorange]

I am currently trying to chase down a similar problem. I have a bad vibration at that starts at 3500 rpm and up, and a light shake at idle, I originally thought that it was a balance shaft problem and replaced The belts and realigned the balance shafts. everything was perfect when I took it apart but I re-did it anyways. I bought the car with the tranny out because the kid took it apart to replace the clutch (Spec stage 1). He neversaid that he had these vibrations and I am starting to suspect a flywheel/clutch problem since the vibrations are definately in the engine area and not the tranny/driveline since it will vibrate with the clutch in or clutch out. moving or not moving.

Has anyone had balance problems with their aftermarket clutches? I have a SPEC stage 1 clutch that I just installed 300 miles ago and this motor has shaked since I got it running. How do you fix the imbalance problem? Can a machine shop balance the clutch and flywheel together?

Sorry to hijak your thread but we seem to have VERY similar issues,
Nick

 

[Melio]

seems simple, but check your motor mounts while the engine is running at 3500+

see if the engine is physically lifting .. sometimes when you replace transmissions, (nearly always) people remove the engine, OR they lift one side and not disconnect the motor mounts on the other. so it streches them.

It's possible they were damaged a little and the engine isnt being tightly held in place.

of course engine vibration like that isnt JUST motor mounts. but take a look anyhow.

could be just that.

(replacement motor mounts are cheap, and very easy to install with a hydrolic jack and a little effort)

 

[gurrmanator]

I just bought a 91 tsi talon and the engine has a violent vibration when rpm's are at 3500 and above, no vibration at all when below 3500. I can see that the transmission was changed because of the writing on the case. When I raise the hood and rev the engine I can see the engine vibrating. the car runs well other than the vibration.

it could be the flexplate/flywheel(auto/manual) Or look and see if anyone has messed with the timing belt....u can see if the bolts have been touched lately...chances are that if they changed the belt they got the oil pump shaft /balance shaft out of time....very easy to do...im doing one rite now

 

[JRod]

.....I have a resonant type vibration that starts at 2700 rpm and quits by 4000 rpm. I thought it was exhaust resonance, so I swapped a few things, and couldn't make a notable difference. Replaced the motor mounts, no difference. I am next going to try a new crank pulley/harmonic balancer. Have you check that yet??? I really just hope mine isn't an out of phase bal shaft.

 

[Defiant]

Rear balance shaft is 180° out-of-phase.