Ok, I've got a 98' 4.0L with 190,000 miles. It's got a ticking sound that goes away under load. It carries 40+ oil pressure. I can't tell if it's rod knock or wrist pin or a collapsed lifter. Any suggestions on how to narrow it down?
It's the distributor type. I thought similar about the oil. What do you think about 20W50? I feel it's a ticking sound and I thought it went away under load but it just gets quieter. I'm thinking it's a wrist pin but I just don't want to admit it.
I tried the plug thing and didn't notice any difference. I've always prided myself on knowing engine sounds and been pretty good at figuring them out. But this one's stumping me. I changed the oil to 20w50 and no change in sound. As I drove it today, the word chatter came to mind, It doesn't sound like a rod knock, more of a chattering sound but it gets quieter either accelerating or decelerating. I doesn't matter if the engines cold or hot, the ticking/knocking sound is there.
I had a 91 YJ with a 4.0 that I bought with 67k miles that had a similar noise. Before I bought it, I took it to the dealership and got one of their mechanics to listen to it. He called it piston slap, and I bought it and drove it another 120k miles. I don't know if this is the same thing, but there's the 411.
well, I found my knocking problem. My worst fears were realized. Found a chunk of piston in the oil pan. I'm gonna pull the head and drop in a new piston, but that's it. I hope to do it in a weekend or so.