I recently purchased the jeep. couldn't worry about the problem too much because of the price and excelent condition of the body. the gentleman that owned it, let his son drive it and he drove it off road. The undercarriage of the motor was caked in mud. when they cleaned the mud out and restarted it the engine had a knock. They believed it needed a new engine. it's not really a KNOCKING, more of a ticking or tapping. it doesn't get louder with raised RPM's. Before I drop the engine, i was just wondering if anyone had experienced the same problem or maybe knew what it was.
Knocking in Lower Engine on 1990 Jeep Wrangler
by lilhogge in Kilmarnock, VA on January 05, 2010
ANSWER by Andy Y , January 05, 2010
If it is truly not a rod knock, I would be looking at the timing chain. Get a timing light on and watch the timing advance. If it isn't stable, there's a good chance the timing chain is loose. With the advance floating around, this could be why you don't have power. Use a long length of hose as a stethoscope to try and isolate the location of the knocking/ticking. A long screwdriver works well for this too. One end goes in your ear and the other can be placed on the part or area. Be careful of the spinning fan!!