Engine Vibration

[Mannster]

I'm wondering if anyone has any ideas on where I can look to resolve an ongoing problem. My engine vibrates pretty bad when accelerating from about 30mph on up. The vibration decreases as soon as I lighten up on the accelerator and stops when I hit the clutch. I can accelerate slowly and minimize the vibration but not altogether.

The things I've done/checked are: timing, all cylinders firing, plugs, distributer cap, ignition coil, fuel filter, and tightened motor mounts.

My Jeep is a 1979 CJ7 6 cylinder. I appreciate any help and advise.

 

[thiswontbetooexpensive]

Sounds like it could be U-joints or clutch. U-joints are easy, shake and replace if necessary. Check for free-play in clutch and fluid in drivetrain as well.

I'm not the expert, I'm sure one will be along shortly...

 

[Mannster]

thiswontbetooexpensive, thanks for the reply. The clutch seems great - but what do I know. As for the U-joint, that would be great if that's it - I know I can handle that. Clutch, not so much.

 

[tarry99]

I'm wondering if anyone has any ideas on where I can look to resolve an ongoing problem. My engine vibrates pretty bad when accelerating from about 30mph on up. The vibration decreases as soon as I lighten up on the accelerator and stops when I hit the clutch. I can accelerate slowly and minimize the vibration but not altogether.

The things I've done/checked are: timing, all cylinders firing, plugs, distributer cap, ignition coil, fuel filter, and tightened motor mounts.

My Jeep is a 1979 CJ7 6 cylinder. I appreciate any help and advise.

How is it at 65 mph?

From the top:
Motor and Transmission mounts
Clutch & Flywheel or Vibration dampner
Driveline , U-joints
Tires & balance
Suspension both front and rear.

 

[Mannster]

I only get it to 65 when I'm going down hill!

I'll go through that list tho, and I appreciate it. I've check the mounts - all good. Tires are balanced. Clutch is something I think I'd have to have someone else check - I have no idea how to check that. As for the u-joint, am I just looking for play in the joint? And same question for suspension? What should I be looking for in suspension that would cause the vibration?

 

[tarry99]

I only get it to 65 when I'm going down hill!

I'll go through that list tho, and I appreciate it. I've check the mounts - all good. Tires are balanced. Clutch is something I think I'd have to have someone else check - I have no idea how to check that. As for the u-joint, am I just looking for play in the joint? And same question for suspension? What should I be looking for in suspension that would cause the vibration?

Anything that's loose......ball joints, Tie rod ends, worn out rubber inserts at the ends of your springs,
On the clutch , try revving the motor while standing still w/ the Transmission in neutral, if it does not vibrate then it should be fine... that will somewhat eliminate the motor and clutch , then start looking for things that are in motion at the speed when it is worst.
Sometimes you can also Jack up the vehicle on 4 jack stands under the axles so that the suspension is under load and run it slowly through the gears while someone is outside watching and listening........be careful and make sure your on level ground.

 

[Mannster]

Great advice. I'll go through those steps. Thanks again!

 

[mtnwhlr]

When I had this problem it turned out to be the water pump. It wasn't leaking but I could grab the fan and move it back and forth I found it when I had it running and when I reved it you could see it moving around. And it was on a AMC 258 i6 / 4.2l .

 

[Mannster]

Great info, I'll check that out as well. thanks!