Update - Here is a video of the sound



I bought this with a blown head gasket and bad water pump and a noisy lifter(s).

Since, I have changed the head with a rebuilt one, all lifters, and I have dropped the oil pan to check for a loose/worn rod bearing....everything is really tight...I can't find any slop anywhere in the oil pan...checked Cam and wrist pins too.

I did get about 1/8 turn on the flex plate bolts, but they seemed snug enough to me. Just because I was there I went ahead and removed, added loctite , and reinstalled the bolt. Flex plate does not look cracked, but could be right at mating surface????

Oil pressure is running about 40 cold and 15-20 hot..moving up to 25-30 above 2k rpm.

I looked for an exhaust manifold crack, but looked fine.
Anything else I should check while I have this apart? Oil pump?

I have checked everything I know to check, and read and searched through a lot of threads. Kinda stuck.

 

Flex plate cracks at the crankshaft flange.

 

It's supposed to be hard to see for some people.
Lots of threads here for advice though.

 

Was wondering how to check for a cracked flex plate and found this:
https://www.cherokeeforum.com/f2/fou...emoval-171945/

 

Here is the video.


Updated original post above as well.

Tried a stethoscope but it echos everywhere and it's really hard to pinpoint. I guess I should drop the tranny and check the flex plate?

Seems if it were a rod knocking it would do it at all RPMs?

 

Sounds like piston slap to me.

 

When I had the oil pan off I ran each piston up and down and all cylinder walls looked very smooth. With piston slap...do the walls become scored/grooved.

I guess I could do a compression test too. I'll post my results when I get a chance.

 

piston slap is normal on start up but should go away when fully heated. You have Iron Block and Aluminum pistons, the pistons need heat to expand to be able to stop the slap with the iron block, two different metals cause this issue, it comes with slight piston slap out of factory, that's why people call them tractor or diesel engines. Gets worse with high mileage but nothing to be worried about.

Your video doesn't sound like piston slap to me.

 

This knock actually gets worse as I drive it for awhile, especially if I offroad for an 1hr or 2hr. Much more noticeable when the engine is good and hot.

 

I am pretty confident its not piston slap, could be flex plate crack as someone stated or piston skirt.

 

10-4, I know it's not a piston skirt, I inspected all of those when I had the oil pan out. I also inspected the flexplate per the "remove 3 bolt, loosen 4th method" and it seems solid. Could be cracked on the crank mating flange....just hate to drop the tranny and it be fine...lol I'd be cursing.

 

Sounds like Flex plate or the one place you couldn't check (which is what my 93 did) was a wrist pin.

 

That is a rattle....not a rhythmic knock. Check flex plate!

 

To me it almost sounds like wrist pins.

 

Ok, I dropped the oil pan again because the knock has gotten worse and it's the #1 rod bearing.

Here is what I found.