unusual engine vibration

[limestang]

Hey everybody,

Just recently a strange vibration has been coming from my engine. It only occurs at the lower RPM's of each gear and fades away after further acceleration. In addition, it cannot be felt when the car is idling or when the engine is revved in park or neutral.....just when the engine is under a load. The engine is a 289 with 145,000 miles on it and has never been rebuilt if that helps at all. Any ideas or responses will be greatly appreciated.

 

[2+2GT]

Start with the basics. Do a full tune-up, new wires and plugs, etc. While you have the plugs out, check the compression.

 

[CraigMBA]

I'd do a motor mount check if it were me.

 

[jonfor]

ditto for me, but i have an '87 engine with *who knows* what front cover and accessories? i heard a sliver of information that my dampener was suspect for being the wrong size???

 

[2+2GT]

ditto for me, but i have an '87 engine with *who knows* what front cover and accessories? i heard a sliver of information that my dampener was suspect for being the wrong size???

If true it would vibrate badly, increasing with engine speed.

 

[gtss]

are you sure it is actually coming from the engine, based on what you are describing, the first thing that came to mind is a u-joint/driveline issue.
but it is really hard to diagnose that without feeling it,

gtss

 

[mhjo]

Check also tranny- mount

 

[suki243]

I had a similar issue; check spark plugs; i had the original air filter and cover with the snorkel and everything; one of the wires had cracked a little and would actually jump to the air cleaner's snorkel. I also had to adjust the idle rpm. I did both at the same time so i'm not sure which one did it but i think it was a bit of both.

 

[limestang]

The plugs, wires, and motor mounts are all in great condition. I checked the wheels and wheel bearings themselves just to make sure nothing was loose or going bad and they are all fine. Timing is spot on and I even adjusted the valves and its still doing it. Another thing i did that 2+2GT recommended was check the compression and all of the cylinders were below recommended compression but still within the recommended allowance of each other. Could this be the source of my issue?

 

[Rusty67]

Do you have a stick or auto trans ? If you have a stick, check your clutch adjustment.