engine knocking 1998 disco

[buddycraigg]

Hello,
I am working on a 1998 disco with a knocking sound.

It sounds like a cracked flexplate but the sound doesn’t change if it’s in gear or not.

And it sounds like it is coming from the right side catalytic converter.

I have heard stories of a cylinder coming loose in the engine.
Is there a sure fire way of checking to see if it’s the cylinder?

Also the sound is present from idle up to about 2500rpm

 

[joey]

Check the compression for each cylinder...If it is a bad Cylinder you will find it.

 

[buddycraigg]

thanks.

as a added note...
oops
this is a 1995

 

[joey]

I would also check to make sure your knocking sound isn't just a cracked exhaust manifold....

but this would go away after warm.

 

[buddycraigg]

I wanted to let everyone know what it was in case someone runs across this thread from searching.
It was in fact the honeycomb material in the right cat was loose in the shell and knocking around. Even sitting still in park.
I took off the Y-pipe and cut it open and sure enough the one of the honeycomb (there are two separate parts in there) one of them was broken “against the grain” of the comb making 3 parallel sections.

I welded the shell back together, reused the old flange gaskets and no more knock.
It does sound kinda odd since the cat is hollow now, but i have piece of mind that it's not something in the engine or drive line.

Good luck with your project.

 

[joey]

I hope you hollowed out both cats, or you will have more issues than you can shake a stick at.... One side will try to run lean and the other rich.... big issues.

 

[buddycraigg]

no i didnt. but i only have O2 sensors before the cats. so i'm hoping for the best.