89 Cherokee 4.0L Piston Slap & Replacement

1989 Jeep Cherokee XJ Pioneer Renix 4.6L I6 AW4 NP231 6" RE Lift 35"x12.5" KM2s
This is actually a 4.6L Stroker build which uses aftermarket pistons, but the process is exactly the same for the stock 4.0L. The engine started knocking after 700 miles so it was time to tear it down and fix it.
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[@MERCNRY]

I know this is several years old but I thoroughly enjoyed the testing/diagnosing aspect of the first video. Kudo's

[@DickShooter]

Never too old.

[@Bill_Landis]

I'm a Mechanic, that was an awesome informative video! Thank you, for explaining every detail, most people watch videos that only show parts of this procedure, then they have no idea how to finish it! Great job!

[@oakiemouse]

I am sorry for your jeep problems and taking so long to find the source but on the plus side it made for great video so thank you for that.

[@garyd.7294]

Hey Bud, great videos to a fix!!!! My 2000 Grand is lifted 2.5 and I couldn't imagine going through what you went through! In my younger years yea but not in my 60's. Thanks for keeping your head and demonstrating how to be methodical and persistent!

[@williamb5668]

Wish I had seen this video 2 years ago. Had the exact sound on my 2000 grand cherokee 4.7l, unfortunately it was misdiagnosed and then the unthinkable. The engine died. Put a used one in now its starting again. This time I'm prepared thanks to you. Fantastic job explaining and diagnosing the issue. Wish all mechanics had your dogged determination. Keep up the great work. First responding to a KZbin video ever.

[@tomgordon3273]

Thanks for posting this video. I been working on my Jeep for weeks trying to figure out where the noise was coming from. As soon as I heard yours run you solved my problem. My Jeep is making the exact same sound.

[@Reach3DPrinters]

Mine too... was it piston slap???

[@Cherokee-sz7xi]

Just a suggestion, use a short length of 3/8 hose over the rod studs, doesn’t leave any glue mess on the threads!

[@markcarpenter3600]

Did you replace all if the rings?

[@tearfree1600]

Thank you good idea

[@LittleMikeStarCraft]

Good job man-- I love the sound of a running engine after you've had it half apart.

[@guitar14]

Sooooo much information. By far the best Jeep engine vid on KZbin. Trust me, I've watched them all. Haha. Keep up the good work.

[@smokeydops]

These are old videos by youtube standards but this is really really good mechanic and education stuff thanks for sharing

[@daman9869]

Awesome Nick!!! I'm glad you got it sorted. It sounds great!! Can't wait to build my 4.6

[@ignisfatuuz]

Great in depth vids! I got a 98 Jeep Cherokee Classic with up country suspension option, only owner. Did upgrade to 3" lift kit with new shocks recently though. My first vehicle I ever bought brand new and drove it off the show room floor after I ordered it with the options. Within the last week over the holidays, a noise developed and found your video and others as well. But your's was the best at explaining the piston slap noise that resembled exactly my engine noise, and same location. All though I ride, I'd rather not ride in the winter if don't have to freeze, so I gotta resort to taking Jeep in to dealer and have them fix the issue. Hopefully they can fix it quick with only a rent a car for a day or so. Thanks for your detailed vids!

[@NickInTimeFilms]

Glad my vids help, hope they can take care of you quick!

[@jesseesmith1835]

Hey man i just want to thank you for your display of knowledge. Great work

[@philjackson9996]

Great idea taping the piston rod stud to prevent scratching the crankshaft -- scratches on the cranshaft lead to noise & needing a new crank!

[@timtomlinson6173]

Great video. Thank you for all the great details. I have the same issue. I may bring mine to the shop.

[@chrisk8794]

Thanks for sharing. Had the exact same noise and broken piston in the #6 cylinder.

[@mikedent4197]

nice job, as loud as it was i was thinking wrist pin from the start. a quality repair you performed for sure.

[@LusiTron]

The problem was your wrist pin, not enough clearance when installed, or oil starved. you can see the discoloration on the connecting rod and it seems to be chipped. It forced the piston into the cylinder, and, well, you see the results...

[@GrussimoGarage]

the rod is discolored from heating it to install press fit wrist pins. But I agree, the piston/wrist pin clearance seems tight.

[@dehavenp.2404]

Thanks a lot for the idea of changing the piston while leave the block in the Cherokee. Saved me time and money. Good instructions.

[@Rotpuck]

I’m having this same problem and just watching all the effort, time, and dedication that goes into this my head is spinning 😂 I’m just hoping it’s only one piston

[@plumberman19]

Did anyone else notice that the connecting rod was seized to the piston? They were not moving freely and independent from each other, also the piston end of the connecting rod is discolored, meaning it got REALLY hot. This was likely lubrication failure at the wrist pin/con-rod connection point. When they seized together, it started torqueing the piston inside the cylinder forcing the piston to start grinding into the cylinder wall. And since aluminum is much softer than steel, you see most of the wear on the piston, not the cylinder wall. This is a total bummer dude :(

[@bedlamite42]

Jeep 4.0 piston pins are an interference fit on the con rod. The discoloration is normal from heating the small end of the rod to fit over the pin during assembly.

[@tomsmith2361]

@@bedlamite42My 01 XJ was purchased from 3rd owner in 2019 with 187K. Heard low end knock at idle, bought it anyway. Had Jeep dealer pull oil pan and was told bearings good, and noise was coming from 2 loose/worn wrist pins. Sounds good while driving and made 3 cross country trips, at 204K now. At 195K or so had camshaft, lifters, rods, timing chain replacement at a different Jeep Dealership in Maine. Then ran it to North Dakota just fine. My 93 XJ ran great for 26 years with hardly a problem at all. Sold it at 199K and bought the 01. Long live the XJ 😊.

[@adammangan1342]

Awesome video . Lots of information . Keep it up . Now I can go fix my daughters Jeep 😊

[@michaelsanchez5805]

i also have an 89 XJ and have the exact same sound i believe you just saved my ass sir thank you.

[@NizR33]

wow... I was wheeling and heard Something let go... only slight unusual sound .... thought it was something to do with the lifters .. but after hearing your engine... I think I have the same issue... When the Motor is Cold it is very loud slap, but once it warms up it only Slaps when I'm underload.... yep makes sense now... Awesome vid and thanks... Ive driven about 100km with this noise Hope I haven't cuased to much damage.

[@omaralblowi6278]

I have the same noise in my XJ 99 , you save my time, thanks , I am going to fix it soon

[@luislunatorres2831]

I seriously learn a lot in this video my car has a piston slap and I thought there was no hope this video just gave me hope to fix my car

[@Spikernaut]

I’m so happy you fixed it Bro I’m going to have to do the same thing

[@nickj6275]

This video definitely help I found the piston skirt in my oil pan

[@nickj6275]

@Ricky Barber well it was knocking when I bought it I was a sucker and bought it anyways since it was $500 bucks I sent it to the ketchup redline and I heard a snap and a pop. I just swap it out with a ls engine (5.3)

[@tv10morehead]

Some one told me the 1998-2006 4.0L have thinner pistons that won't go 200K miles, they being a former Tractor mechanic put 1991 Pistons rods and crank I think into a 2002 and have ran it 20K miles so far. I had a 1997 Cherokee Sport 4.0L that went 398K before what we were told was a WRIST PIN but now I think it just needed new pistons

[@jamieblair8673]

Yeah I noticed one of the other guys posted it yeah you did make a really great video on this they have this helped me out a lot I do appreciate it I dig your videos

[@mrghonea]

Great video! I've been searching for a week trying to figure out this noise. Watched this video last night, pulled the head today and it was a very slight piston slap. Nothing a little honing and new rings won't fix. Solid video. Keep it up.

[@zackgarrett1278]

Love the copper look. Thanks for the video.

[@johnnynoche1387]

Dude that's awesome, you need a beer man.

[@DeepStateDestroyer]

Couldn’t of asked for anything else thanks man! Keep it 100

[@keithcerce8445]

And the valve cover looks like a million bucks. Nice job. Glad the um.... Rebiuld... Worked out for you

[@ronmcdade2865]

Im planning to do this on my 4.3 vortec. Very informative and useful info for any diyer

[@jacobyoung3102]

That’s a badass valve cover

[@DarkM34T]

Great info. This may be the problem with my 93 cherokee. Thanks for the video

[@Amarillobymorning777]

Did it get fixed?? Pancho.

[@OutnBacker]

Had a 96 Cherokee for 8 years, piston slap was there, but more typically the quiet low knock. Just bought a 95 GC, and the sound is there as well. Low end knocking. Yours was the loudest I have ever heard. I have often wondered if the short piston skirts contribute to what may be inherent wandering of the piston as it moves up and down, absorbing all the tolerance stack-up and making noise as a result. With all the 4 liters doing this, I'm assuming because they normally don't suffer for it.

[@TheMrDmack]

Good job as always. Thanks for the information

[@4wheeldriverican]

I defiantly learned more about the 4.0 while watching this video

[@adrienroy9310]

Good video. Good job. Would have liked to see the honing.

[@duanealbers7175]

I use a deep socket with an external hex on the top outside. Then i use a horizontal extension/crowsfoot and calculate the difference,, works good in lots of places like that rear bolt.

[@blaing3354]

That’s quite the job to do in the truck, wow. Kudos

[@jamesmichael3998]

Great job. Cheers from Jacksonville Florida

[@trickypete887]

great video, and love the colour choice!

[@michaelmallory9490]

Just FYI you can use rubber hose on the studs when removing and installing the pistons instead of duct tape they seem to stay in place better. Anyway great video I might be doing this same job here soon.

[@ducatidude4483]

I just had this exact thing happen after installing my stroker. About 10 miles after installing it. I was thinking maybe it was a spun bearing till I pulled it back out to investigate. I had .014 ring gap on that piston. Sad to see a brand new ic945 ruined..

[@ilovegodforever100]

awesome man, you should make more videos of you just driving around. haha maybe a good old 0-60? love the vids bro!

[@michaelmessenger3614]

@nick I've been watching your videos to help me get the transmission out got everything done but now won't start . you seem to know a lot about these Cherokee's Help haha

[@user-cu4zl9jn4n]

nice! thanks for sharing this. Very informative. So to be clear, initially when you got that sound it would happen all the time correct? From cold start to warm and continue... right? (*edit* n/m i just read in the comments it was constant)

[@dedrickgirley8605]

Awesome camera work

[@one100billneoone4]

Awesome video sir. You are freaking awesome. Thank you.

[@russellking201]

Thanks for the video. Suggestion when it comes to the socket. Can we just buy a deep socket and then grind or cut it to the best length?

[@randallcribb668]

I'm not a Jeep man but I have 45 years experience as a mechanic just wanted to drop some info, check your rod for a oiling hole in the rod near the rod bolt , some 6 cylinders had a hole in the rod to squirt oil on the piston skirts , don't know if yours has the hole, but keep it in mind if it happens again, hole could be clogged up.

[@cocainechestpains]

great vid man

[@LittleMikeStarCraft]

Cherokee's here are still fairly plentiful and cheap.. so I am planning on just buying a parts Jeep and pulling the engine and rebuilding it in my free time.. so when/if my 4.0L ever starts acting up I can do a little swaparoo.

[@carloscartaya9932]

Great video! Lots to learn from.....by the way, do you use it mostly off-road, how many miles on the engine? Thanks, peace

[@jon_pitt]

Great that you take the time to post this shit for all us knuckleheads

[@Stevesmods]

also ill do a video of mine over next few days , my truck been sat for aprox nine months , has a tapping sound now , if you could take a look once ive done it

[@JoeVizethum]

great video ! Did your machine shop guys also hone the cylinders ? What piston size did you use after honing ? Thanks !

[@FD-dh2fu]

Amazing job. What would a job like this normally cost? Thanks.

[@TheVaevictus24601]

If you have an extra deep well socket the size of that back head bolt you can cut it down to shorter than a deep well but longer than a regular socket. Then you won't bust your knuckles. Nice work by the way!

[@NickInTimeFilms]

I have thought about doing that, just never got around to it.

[@TheVaevictus24601]

If you decide to just don't do what i did and cut up your only deep well of that size. If you do you will need it 5 minuets later. Trust me.

[@AndrewBrowner]

snap on makes intermediate sockets that length.. im sure they wont a fortune for them, milwuakees new sockets have flats on the outside so you can throw a wrench on them in tight spots, i have 3 sets of cheapo mastercraft sockets and one good set from westward so i have no issue cutting into a mastercraft socket hahah

[@CharlesWillisBonsai]

Wow, I'm impressed.

[@williamwhite9767]

A piece of rubber hose on the rod bolts is also a good way to protect the crank and they won't fall off.

[@Jarod1941]

Did your tapping sound diminish as the engine temp rose? Excellent videos (the lifters vid too). Great visuals, description of what you're doing and why. Huge thumps up to you. My new fave Jeep channel. Sub'd.

[@onefastcyclist]

Excellent -thanks for sharing first class "shade tree" repairs ! It's wonderful that AMC left enough room around the engine bay to do this without pulling the engine. But it's even more amazing that AMC's early '60's design is still relevant 53 years later! BTW, How did you solve the exhaust leak that was present at the end of the lifter replacement presentation?

[@NickInTimeFilms]

I just cranked down the manifold bolts a little tighter and it was fine

[@mackacular]

I have a fresh 4.0 rebuild and this exact thing just happened to me, same piston, same scoring. Question for you, was the engine guy able to hone the cylinder from the top without dropping the crank? That's the point I'm at and trying to figure out what to do.

[@chrismeza6977]

I think my Jeep was having this same issue and now it doesn’t turn on. :(

[@sincitydude7296]

great video!

[@Saltinessboy]

But if six cylinder wasn't getting enough oil did you change the oil sending unit

[@gatordave6629]

Any chance you know what the intake and valve sting tension is supposed to be to check for weak valve springs?

[@nickaxe771]

Nice job.....can I ask....did the tapping get any less when the engine was fully warmed up.

[@davidram1974]

my 99 jeep grand cherokee is making the same noise and driving it at 70 mph I heard something broke loose and a few days later that particular same noise . Do you think a piston broke loose?

[@jerrywhalen2100]

When you're honing the cylinder how did you keep the crank from getting so dirty

[@tomaszstaron1408]

Exacly the same kind of noise in mine 4.0 Grand Cherokee ZG (european made in Graz). And as I see, a lot of work to vanish it ;)

[@Garrett053]

What was the problem with the oil flow then?

[@trgoles]

Job well done!!

[@svborek]

1500 mile motor I had the same thing just happen. Same cylinder too look exactly like yours did.. my wrist pin was almost seized to the pison

[@svborek]

All fixed. Sounds and runs great again. Only took 5 hours to put the whole thing back together.

[@timothyeschedor5750]

Great video! Could you elaborate on whether or not you honed the cylinder? If so, how? Thank you in advance!

[@NickInTimeFilms]

The engine guy just brought his flexi-hone and ran it on a drill for a few minutes to clean it up. Luckily that's all my engine needed before putting the new piston assembly in.

[@chrispirri8145]

Was it only making noise after the engine warmed up or also when it was cold?

[@hayzersolar]

so looks like you removed the ac and put the alternator in its place how hard was that

[@hallhouse5098]

I’ll be pulling my pan off. soon on my 99. Sounds like #2 or three slapping or rod bearing noise. Noise definitely near crank under pan. I have 280-k original miles on motor. Knock is slight bit used to be only when cold and would go away but now gets quieter when warm bit still there under load when warm. I have a 4.0 from a 1995 xj that I plan on building to have ready to put in if this 99 blows up or build the 95 and install it before my 99 blows up then build that one also. I haven’t been able to get an answer anywhere whether or not the 95 motor will accept all my 99 accessories in the same alignment .

[@NickInTimeFilms]

Hard to say. Id assume the blocks are similar from that era as far as mounting holes go. Might be worth looking up comparisons online of the different year ranges.

[@bueler4950]

So the Piston was not cracked or broken? Or was there other damage that we could not see in the video? I'm surprised at the noise was that loud with just some scoring on the skirt of the piston.

[@studiomoris4542]

very interesting, how many hours did it take ?

[@Spikernaut]

Ok so I have the same issue on cylinder 5 did you use a stock sized piston

[@geovannysolorzano2319]

WHAT I NEED TO DO TO CHANGE MY PISTON RINGS??? ANYTHING AROUND THE PISTON???? (

[@Stevesmods]

bud big help this is , i for sure will be shareing

[@WillysOverland]

So what was the cause for the oil loss?

[@davidgomez3737]

I know this is a stupid question but how did you move the piston in the motor im about to open up my motor for the first time ever in my life first timer here

[@ralphnabozny8494]

is the head cracked at #6 ? you do nice work. So that is what it is supposed to sound like. wow

[@samwiley4103]

I need that done too

[@Prepping2endure]

for that rear head bolt? could you replace it to a non stud type or cut the upper threads off?? i have to pull my head on a 96 xj that had the distributor gear take out the gear on the cam.. just curious if that could be done. Love your Vids full of great info. Also cool that you're from NJ as well.

[@NickInTimeFilms]

Don't see why not as long as its a proper Bolt. I'd probably just hack the top off 1 in the set

[@Wolfsar]

Can this problem increase blow by?

[@noearias2006]

Excellent. Video thank you

[@go4itpc]

He stole my work coat.

[@getsmart2594]

ha ha ha....i am laughing, because the sighs are very similar to the way i take on projects with vehicles. LOL, its like jump in, complain, undo this undo that, complain, maybe even cuss a little here, take more stuff off or apart, few more sighs. Your true blue human ! At least you have your experience that you can fall back on and your not totally in the dark. Great Video ! "NO MORE NOISE ! YES SIRE EEE ! SWEET BABY JESUS ! "

[@NickInTimeFilms]

+Michael Laverty This was a freshly rebuilt engine, only had 600 miles on it. Friend overheated it, wrist pin seized up, scored piston skirt. New piston assembly installed and she's been running strong for 6,000 miles now. Hi volume oil pumps are just asking for trouble, heard more bad than good, mine is fine.

[@markbreaux6613]

So, you changed from a high volume oil pump, to a regular oil pump? Just asking cuz you said it might've been an oil control problem?

[@nickconrad94]

Mine has the exact same noise. Is Piston replacement doable on my own? I am SO over spending money at aa shop.

[@NickInTimeFilms]

This entire video shows you how to replace a piston, so that is your call if you think you can do this. I wouldn't call it difficult, but it's time consuming since the head has to come off. Only thing I had the engine guy so is mount the new piston to the rod, install the rings, and tap it in. I bolted it all back up and it worked fine.

[@nickconrad94]

Just finished the video. Didn’t look to bad. I’ve definitely done as hard or harder work. The shop the Jeep is at right now (getting re geared) is pretty confident that it is a rod bearing but hearing what my Jeep sounds like sounds like piston slap. Would you mind checking out the video I posted on my account to see what you think? (If it sounds similar to yours) thanks!

[@nickconrad94]

Another point to note- mine got rebuilt just likes yours did at 158,000 miles. Had about 3k on the clock when it started ticking

[@adibrahiem7193]

Good job

[@lazy402boi]

3 years later and now I'm having the same issue😆