Jeep newbie here. Just purchased a 2002 wrangler with a 4.0 engine and manual transmission. It will start up and run super smooth some days and others it sounds like a rod knocking in it. Oil pressure comes up a little slow but stays around 40 psi consistently. I’m really confused on what’s actually going with this motor. It has 200,000 miles on it and it could be several things but how can it sound like it’s going to orbit a rod any second and a day later it’s quiet and runs smooth??
Rod knock noise
- Thread starter Crankbait65
- Start date
You sure its rod knock and not a collapsed lifter? Might be the oil filter draining empty over night and until filled and oil is moving is a possible culprit.
Start with changing all the fluids!
At some point clean and inspect all your grounds.
Might see more if you pull the valve cover.
-Mac
At some point clean and inspect all your grounds.
Might see more if you pull the valve cover.
-Mac
Collapsed, sticky lifter. Try a high mileage oil, or the new Valvoline Restore and Protect seems to really clean up motors. My YJ would do this, ran M1 HM through it for a few changes and it cleared up. Hasn't done it again and it's been at least 10 yrs. Been running M1 0w-40 since then.
Cracked piston skirt.
Cracked piston skirt.
I had an engine (454 Chevy) start knocking, then not, then knock, then not, then she was so down on power it wouldn't move the vehicle. This was over the course of about an hour of driving. It turned out to be a bearing spinning, which destroyed the crank. I say that to say it is possible that you have a rod knock that comes and goes, but it won't do that very long. I suggest starting by draining the oil and cutting open the filter to see if there is any glitter. If clean, then probably not rod knock, move to the next thing.
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