It sounds like its coming from the oil pan .Thats where its the loudest. What can this be? Its a 94 ZJ with 171,xxx miles on it. It runs good but does stumble at times. I've had it for a month now. I've had about 8 times where it will start and idle really rough, but then it smoothes out and runs fine. One time it wouldn't start at all, I put a quick shot of ether in it and it started right up. I pulled the throttle body, tps and iac, cleaned them and relpaced the fuel filter, air filter, plugs and wires. Also it has a new complete exhaust system. Any ideas? Thanks. Its an auto.

 

Crank maybe?, Possibly the oil pump

 

Anyone?

 

it's an automatic tranny correct?

I would get under it and check all of the bolts on the torque converter. Its a pretty common problem that they will come loose and make the sounds you are explaining.

Hope that helps,
Matt

 

so ,should I run it til it blows and junk it or what?

 

Mine has knocked for a year and still runs great. It's a Jeep thing

 

yea i would run it till you find a cheap motor to replace it with i have went 3000 miles on mine..and it sounds like a submachine gun lol

 

my old engine knocked for ever and finally blew at 248k. Hey you need a engine 4.0. I have one laying around with low miles

 

I would check the converter bolts, but if that do not fix, rebuild engine. I did many engines and it is not that much complicated. Most of the time, you can change the crank bearing with engine in frame. Do not mix the caps.
If crank is not damage then drop the pan and change one at a time.