Chassis Vibration 1989 454 when idling

[spyro92]

Hey,

My baby (1989 Chevy 3500 7.4L 120K miles) recently started vibrating when idling. It was barely noticeable at first, but it has been getting worse.

At first I felt it through the steering wheel, but now the entire chassis vibrates. When I cold start the engine and the idling is at a higher RPM to warm up it's not noticeable. But when the engine warms up and the idling drops down to lower RPM thats when I can feel it.

There's also a suspect noise on the passenger side of the engine, recording here:

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Does anybody know what it might be?

Thank

 

[b454rat]

I've heard over time the balancer can slip, causing the engine to be out of balance. Is it running on all 8?

 

[Schurkey]

I've heard over time the balancer can slip, causing the engine to be out of balance.

Possible. Not tremendously likely.

Is it running on all 8?

Very likely that this is another every-day misfire.

How old are the usual "tune-up" items? Cap, rotor, plug wires, plugs, fuel and air filters, etc? When were the various systems checked--initial timing, electronic timing advance, PCV, EGR, heated-air intake, etc?

Connect a scan tool, find out what the computer wants you to know. "Codes" are fine, but the real knowledge is in the data stream.