Hi guys. I'm desperate for some help and hope someone can point me in the right direction. I've spent about a week on forums trying to find a solution but to no avail. About 200 YouTube videos later and I can't find a similar noise.
Here is the rundown.
99 Jeep Cherokee 4.0 with 66k miles. The Jeep still looks and smells new. It's like a time capsule. I've owned it for one year. I had an oil change when I first got it and have only put on about 3500 miles. This knock possibly didn't start until after the oil change I just did a few weeks ago.
The sound is a slight knock/rattle that only seems to primarily happen on light acceleration. The rattle does not have a pattern. The noise only occurs when it gets up to 200 degrees or so. After 20 minutes of driving it seems to go away. When I do have the noise it is around 1500 rpm. It goes away after that. I can't really hear it driving over 30mph. I can get it to do it in park as well.
I could not isolate the noise with a stethoscope so I brought it into my mechanic who primarily deals with Jeeps. They thought it was possibly lower end but then still weren't too sure. It's not the flexplate bolts,they were all tight and they didn't see any cracks. I can't see any cracks in the exhaust manifold. It does not sound like piston slap or rod knock or a noisy lifter.
Here's something else I'll throw out there. I had researched oil for hours on bobistheoilguy and decided to use Pennzoil Yellow bottle 10w-30 on my last oil change. This is supposed to run great in the 4.0's and have a good amount of detergents in it. Is it possible the oil degunked something in my engine and it's just getting clogged up? Since it only has 66k I am assuming there may be some build up from sitting. I also used a purolator pureone filter. My mechanic took it off and noticed it was rather heavy and the oils that I had just changed was pretty black. I got the Jeep back home yesterday and just changed the oil again with Pennzoil and substituted a quart for marvel mystery oil to hopefully further break everything down.
Any other ideas guys on what it may be? If it was the exhaust manifold or gasket wouldn't I be able to hear that noise loudest with the stethoscope on it? It seemed quiet but the fact that it goes away after hot would lead me more towards exhaust. The mechanic had an electronic stethocope and still couldn't pinpoint besides lower end and oil pan which most vibration will echo down to.
I'll try to get a video later if it helps. The jeep is hot now and not doing it. Thanks in advance for any sort of help and sorry for the novel.
Here is the rundown.
99 Jeep Cherokee 4.0 with 66k miles. The Jeep still looks and smells new. It's like a time capsule. I've owned it for one year. I had an oil change when I first got it and have only put on about 3500 miles. This knock possibly didn't start until after the oil change I just did a few weeks ago.
The sound is a slight knock/rattle that only seems to primarily happen on light acceleration. The rattle does not have a pattern. The noise only occurs when it gets up to 200 degrees or so. After 20 minutes of driving it seems to go away. When I do have the noise it is around 1500 rpm. It goes away after that. I can't really hear it driving over 30mph. I can get it to do it in park as well.
I could not isolate the noise with a stethoscope so I brought it into my mechanic who primarily deals with Jeeps. They thought it was possibly lower end but then still weren't too sure. It's not the flexplate bolts,they were all tight and they didn't see any cracks. I can't see any cracks in the exhaust manifold. It does not sound like piston slap or rod knock or a noisy lifter.
Here's something else I'll throw out there. I had researched oil for hours on bobistheoilguy and decided to use Pennzoil Yellow bottle 10w-30 on my last oil change. This is supposed to run great in the 4.0's and have a good amount of detergents in it. Is it possible the oil degunked something in my engine and it's just getting clogged up? Since it only has 66k I am assuming there may be some build up from sitting. I also used a purolator pureone filter. My mechanic took it off and noticed it was rather heavy and the oils that I had just changed was pretty black. I got the Jeep back home yesterday and just changed the oil again with Pennzoil and substituted a quart for marvel mystery oil to hopefully further break everything down.
Any other ideas guys on what it may be? If it was the exhaust manifold or gasket wouldn't I be able to hear that noise loudest with the stethoscope on it? It seemed quiet but the fact that it goes away after hot would lead me more towards exhaust. The mechanic had an electronic stethocope and still couldn't pinpoint besides lower end and oil pan which most vibration will echo down to.
I'll try to get a video later if it helps. The jeep is hot now and not doing it. Thanks in advance for any sort of help and sorry for the novel.
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