I have a 1992 cherokee with the 4.0 HO automatic. The motor is making a knocking sound and gets faster when you rev it a little. Im really hoping its not a rod knock, any ideas on what I can do to be 100% if it is or isnt a rod bearing? It also has a valve tap but im not worried about that I will fix that shortly. Thanks!

 

You can check your flex plate for cracks an loose mounting bolts.

 

Like RT says, a thing to check at any time, known issue. You pull the little dust plate on the bottom/front of the bell-housing. The toque converter to flex plate bolts are up in there.

 

If it's making noise at idle there is a good chance it's the flexplate. A rod knock usually is heard at around 2000 rpm and has a sweet spot at a certain rpm. You will also notice low oil pressure.

 

Here's how to do it. So common, most of us consider it maintenance at this point.

https://www.cherokeeforum.com/f51/ho...ocking-125547/

 

I will check the plate and bolts after work today. I have good oil pressure (around 42-45) so im really hoping that means its just as simple as you guys said. Thanks for all the info and I will let ya'll know!

 

can also remove and cut open your oil filter. a bad bearing or something creating rod knock isn't limited to rpm or oil pressure.

we thought dads truck was knocking and it turned out to be the flex plate. so hopefully that's the culprit. this was a lt1 eng btw.