Vibration after new mounts and Dampner

s10quinn · Dec 1, 2003

I just posted 2 threads and got plenty of help. Enough to fix one problem and further test another. Thanks from all who helped.

Here's my third problem:

Got a new motor that ran good in the wrecking yard. I dropped it in. There was tons of vibration in the motor at idle, in motion, clutch in and clutch out.

After changing out my motor mounts with a new set, the tremedous vibration still persisted, there was definately a reduction in vibration because the mounts were definately shot.

But still plenty of vibration remained, certain rpms made the vibration go away.

I saw some twist in the harmonic balancer so I pulled the one from my old motor (no vibaration before in old motor) still the vibration remains.

I go to the other end of the motor, I haven't put the cover on the flywheel to bellhousing yet. The flywheel is spinning perfectly true.

The trans mount looks fully intact, nothing like what my motor mounts looked like. Could it fool me? It kinda feels like the vibration is closer to the cab, possibly under my ass?

Everything looks solid under there. (Headers were dropped for motor swap)

Truck pulls very well, no hesitation, but the rpm of the motor is what drives the vibration.

All pulleys spin true.

Do I go back to the tranny mount?

tom3 · Dec 1, 2003

Don't know the exact details, but the 2.8 had a changeover from internal balance to external balance from year to year. I'd guess you have the wrong flywheel on the replacement engine. Search the forums for external balance and you'll determine when the change was made and if your engines are different.

SY2932 · Dec 1, 2003

60 degree V6 evolution: http://forums.s-series.org/viewtopic.php?t=52 HTH's

Mike Campbell

s10quinn · Dec 3, 2003

I looked at the link provided by Mike Campbell, looks like it was '88 that had the internal balancing, I have an '87 motor (external). At any rate, the flywheel is the one that came with the motor (aparently) so it should be a match to the engine. When I picked up the motor, the flywheel had been removed.

The wrecker says,"Yeah, I always sell motors without flywheels."

I told him, the flywheel stays and that he should never have taken it off. I walked away with the flywheel pressure plate, and clutch in hand.

This vibration couldn't be caused by the pressure plate could it?

I ordered the tranny mount, $16 canadian, not bad, its the last of the mounts to be changed out. After that, I guess the tranny has to drop and a closer inspection made?

bobgolding · Dec 3, 2003

There isn't a chance that the wrecker gave you an 88 or later flywheel is there? Did it have the same welded weight as you original?

Dr.Fiero · Dec 3, 2003

87 was actually a crossover year - some were internal, some external.

If you've had the pan off, look for a large disc like object about half way down the crank. That shows that it's an internal balance model (it was for the DIS rig that was to follow). If so, you should have no bumps on the front face (engine side) of the flywheel.

All the clutches are neutrally balanced, so they can be used on either configuration.

Ditto goes for the harmonic dampeners as well.

Vibration after new mounts and Dampner

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