Engine Engine Knocking/Shaking

[MikeMirage]

Figured I'd give this a shot. Newly, inherited 76 CJ7 and there appears to be a knocking noise while idling (just got it started and no idea how long it has been sitting). Was wondering if any one had an idea what to look at? I've attached a video to see if that helps. Any ideas are appreciated!

View attachment 20250723_124318.mp4

 

[Manic Mechanic]

It's not a rod knock. To inconsistent. A rod knock would be more rhymatic (sp)

I'm thinking maybe collapse lifter or broken exhaust manifold.

 

[Finno7]

Start with

Figured I'd give this a shot. Newly, inherited 76 CJ7 and there appears to be a knocking noise while idling (just got it started and no idea how long it has been sitting). Was wondering if any one had an idea what to look at? I've attached a video to see if that helps. Any ideas are appreciated!

View attachment 104562

Start with the timing!

 

[CJ]

It's not a rod knock. To inconsistent. A rod knock would be more rhymatic (sp)

I'm thinking maybe collapse lifter or broken exhaust manifold.

Can't tell you how many crazy, hard to diagnose engine knocks I have traced back to something having to do with broken exhaust. Sounds like a flapping, rattling or loose exhaust part.

 

[MikeMirage]

I haven't gotten a chance to fix it and test if it is for sure the issue, but there are large leaks on both sides of the exhaust manifold. Thanks for the help. I'll report back when it stops raining and I can work on it

 

[CJ]

I haven't gotten a chance to fix it and test if it is for sure the issue, but there are large leaks on both sides of the exhaust manifold. Thanks for the help. I'll report back when it stops raining and I can work on it

LOL - When it stops raining... I too live in the Sunshine State ! Its pouring on the other side of my neighborhood right now but sunny here. Give it twenty minutes and it will be reversed...

 

[jzak]

Can't tell you how many crazy, hard to diagnose engine knocks I have traced back to something having to do with broken exhaust. Sounds like a flapping, rattling or loose exhaust part.

Like what CJ said, I doubt it's a timing or rod-knock problem. I've had those issues, and my CJ didn't sound like a broken driveshaft. I also think it could be something in the exhaust. Does the sound change or go away, when you step on the gas, or drive it?

 

[rmoledor]

Figured I'd give this a shot. Newly, inherited 76 CJ7 and there appears to be a knocking noise while idling (just got it started and no idea how long it has been sitting). Was wondering if any one had an idea what to look at? I've attached a video to see if that helps. Any ideas are appreciated!

View attachment 104562

I had three bent push rods in my 1978 CJ5 AMC 304 . And there was tons of sludge in the engine it had not been licensed since 1988 when I bought it and had been sitting for years. My advice is try running some seafoam products through it but you're ultimately probably going to need to pull your heads off and take a look at your valve train