94 GMC 4.6L vibration

Check all mounts motor and Trans and so on good luck

thx1138v2 said:

I'm starting to feel a vibration in the steering wheel. It has 250K miles on it. The vibration is slow at idle in the driveway and speeds up as I pull out and drive it. I drove it @ 80MPH for 2 hours today and of course the vibration was gone at speed but it came back at idle.

I'm thinking crankshaft harmonic balancer but don't know how to test it.

Any advice appreciated.

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Watch the harmonic balancer while engine is running, you may see it wobble. Pulleys, belt tensioner, etc. revolving straight?

All good ideas for diagnostics but I didn't find any definite problems.

Harmonic balancer checks out with timing light. My gas mileage is as good as when it was new: 13-15 in town and higher 17's to lower 18's on the highway so I doubt there is any missing. I changed out the plugs, plug wires, rotor and cap just 18K miles ago but it was 3 years - I don't drive much any more. The motor and transmission mounts seem tight and it seems I would feel something when accelerating if it was mounts. U-joints are still good. I didn't see any wobble in the balancer, pulleys, or tensioner.

The only thing I can think of now is some kind of dampener in the steering column. Does anyone know if there is one in the steering column? I don't think that makes much sense because I can feel it in the floorboard if I have my shoes off but maybe...

I might do the plugs, wires, rotor, and cap again as a last resort but I hate to just throw money at it.

The only other thing I can think of is the "drive it till something breaks" diagnostic.

thx1138v2 said:

The only thing I can think of now is some kind of dampener in the steering column. Does anyone know if there is one in the steering column? I don't think that makes much sense because I can feel it in the floorboard if I have my shoes off but maybe...

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The "damper" in the steering is the rag joint connecting the steering shaft to the steering gearbox.

They're a high-failure item, known for creating sloppy steering--turning the steering wheel back 'n' forth an inch or three, but the vehicle doesn't turn. Not known for inducing vibration--in fact, I'd think the sloppier they get, the less vibration they'd transmit.

thx1138v2 said:

I'm starting to feel a vibration in the steering wheel. It has 250K miles on it. The vibration is slow at idle in the driveway and speeds up as I pull out and drive it.

Click to expand...

Does the vibration speed up if you rev the engine in Neutral?

That would narrow down engine/clutch/torque converter/engine accessories (PS, A/C compressor, water pump/fan, etc.) vs. the rest of the driveline.