Jeep Cherokee Forum - Piston slap... questions for those who have or had it.

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- - Piston slap... questions for those who have or had it. (https://www.cherokeeforum.com/f2/piston-slap-questions-those-who-have-had-151981/)

I have a 92. Duelsportdad those vids you posted sounds kind of what my jeep sounds like but mind is quieter and comes and goes at start up and totally dissapears sometimes. I have always thought it was a sticky lifter but watching these video's kind of gets me thinking but i have found that when i switch over to 15-40 HDEO oil helped alot and also did running that Engine Restore that comes in the aluminum cans totaly gets rid of my noise for about 2000 miles a can. SO i just put it in at every oil change.

Radi's link to that lawsuit actually mentions that - apparently a machine in their engine plant was malfunctioning for 7-10 days before anybody noticed.

An interesting read to be sure, but unless your '97 XJ has a 1993 engine with screwed up pistons I doubt the specific issue described actually applies. For '96 Chrysler added a brace to keep the noise down. You could still have a crappy piston though.

Interesting thread. I am a new Jeep owner but have rebuilt other engines. In my experience it is usually the rod bearing at the crank or the wrist pin that wears causing the noise. I haven't had experience where it was just piston slap and everything else is good. However, if piston slap is the cause, would it not cause wear on the cylinder wall that would need to be honed or bored anyway? And if that is the case I would want to inspect the crank and all the bearings and probably replace all those too while everything is apart, unless they all spec out and appear in very good condition. I know I don't have that kind of luck. lol

Is this a common occurrence with the 4.0 or only on particular years? I'm just trying to educate myself so I know what to expect with our Cherokee down the road.

Quote:

Originally Posted by salad (Post 2083637)

This may have already answered part of my question with the affected years. Ours is a 98' so I guess maybe I'm safe for now. :dunno:

I let the jeep sit while I went to lunch with a fan blowing on it. When I got back I started it and the noise was almost non existent. When I turned the key to run the temp gauge did come up some but didn't reach the first mark. Hopefully it was cooled down enough. I'll Lea e it for the rest of the day with a fan on it and listen for the noise. If its gone I'll do one more induction service to it for good measure and call it a day.

I'm still reading through the law suit between working on customers cars today.

Quote:

Originally Posted by hankthetank (Post 2083495)

i work with a hd mechanic that worked at a chry dealer for over 20yrs. we were talking the other day and he actually brought this particular issue up. he asked me 'have you had any piston slap?'
i said no.
he said 'oh thats good, i had to fix a lot of jeeps that had bad slap on cold start up. we had to install new pistons and fit them to the bores, they were all under warranty'...word for word

i'll ask him when he comes in tommorow for particulars on years, which cylinders were always the worst and how a guy should go about fixing this issue himself and report back. hope this will help you out.

well my forklift mechanic showed up today. we chatted about the piston slap. he said basically there was no skirt on certain years, and the remedy was to measure the bores, then match the pistons to the bores based on a color code system (yes, different colors of pistons for bore diameter ranges). the replacement pistons had skirts and a black teflon coating. there was no repeating offenders as far as cylinder numbers...it could be one or all. and he did tell me that he replaced A LOT of short blocks at the time because of badly scored walls. he has a fuzzy memory on specific years, but if he had to guess, he tells me anywhere between 92 and 98 were the most common and when he was doing these jobs the most. hope this helps. hank out

it sound just like the tsb... i bet it was older ones. in 98 a 95 would have still been under warranty... and possibly even 94's depending on the in service date. my 98 made no noise. i do though see plenty of reports on the net about people with 97+ jeeps having the skirts break off the pistons. this is what i'm trying avoid.

Quick update. I started the jeep this morning for a few min and listened for the noise. It was very faint.... I'd say it was acceptable. If I was smart I would have taken my phone and got a video. I'll do that when I get home today or tomorrow morning.

I have a 1990 Cherokee. It runs great and sounds awesome! One of my problems is the flow by from the burnt piston rings. If I let her warm up to pretty hot my oil pressure seems normal. When I start and fit about 15 minutes I'm getting about 70 lbs of oil pressure. How do I figure out the bore of my pistons? Do I need to pull the motor out just the head and oil pan to get to the pistons?