Car Shaking

[SwissCheese]

I have a 66' 230S 4 speed manual, with a 250SE Engine. The car shakes uncontrollably, at idle, while driving, etc.
I replaced the engine mounts and transmission mount with OEM parts. Still shaking like a washing machine.
What are your thoughts? My mechanic said it can be my flywheel, since the 230S engine was externally balanced, and the 250SE engine is internally balanced. The 250SE engine came from an automatic car, so it could be possible.

Thanks

[Sugar Bear]

When did the shaking start or was it equipped with it when you got it?

A freebie to do...check the firing order and then double check it.

If it is the flywheel I guess you could have it balanced independently.

Good luck!!!

[97 SL320]

Do you have both old flywheels / flex plates? It is possible to match balance without too much trouble.

[SwissCheese]

IIRC the car did not shake like that when I bought it. The firing order is correct, and the engine swap was done before my ownership, so I do not have any other flywheels. I'm getting frustrated, so many problems with my baby...

[Dubyagee]

Check for a bad spark plug wire or a bad plug. I would just do a full tune if it hasnt been done in a while.

If all electrical is good then a compression test is in order

[SwissCheese]

Compression range is from 140 to 150 psi. Spark Plug wires have been changed, and new Bosch non resistor spark plugs have been installed.

[Dubyagee]

If so, it would appear a balance weight may have broken loose of the flywheel. Which would be weird on a standard trans. Maybe the crank damper has spun. A video may help.

[BWhitmore]

Check for vacuum leaks. A vacuum leak can cause erratic/shakey engine operation. Using WD40, with the engine running, squirt WD 40 at any suspected vacuum leak (intake manifold gaskets, vacuum fittings, vacuum modulator etc.). If the engine speeds up you have located a vacuum leak.

[97 SL320]

The pressure plate could have thrown a spring ( if it uses coil springs ).

I would not drive the car until the problem is solved.

Do a cylinder balance test by grounding out each spark plug wire and see if one cylinder isn't firing. ( Use 3" pieces of black rubber vacuum hose to make extensions between the distributor cap / plug wire then use a grounded insulated screw driver to short out each cylinder one at a time. )

[SwissCheese]

Lets stay on topic... I will try spraying the WD40 and grounding out each cylinder this evening when i get home and report back. And record a video.
Thanks for all the help so far.