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Discussion Starter #1
Howdy all.. been having a ticking sound while engine is cold but has gone away after about 5-10 minutes warming up. Yesterday while driving about 15-20 miles, the ticking started unexpectedly and got worse/louder the whole drive home. It is now constant warm or cold. Surfing the net, I'm seeing a lot of exhaust manifold gasket or crack, lifters, rockers, valve springs, etc... Wondering if anyone recognizes the sound and can help point me in the right direction.

Jeep 4.0L. 220k miles, compression was damn near factory spec, oil is due for a change but not anywhere in bad condition or low. Jeep is running well, no codes or drop in pressure, no raise in temp or even a lack of power in acceleration. Not seeing any difference in tailpipe exhaust, no misfires.

I posted a short video clip to my youtube page.. here's the link.

Thank you in advance for any input.

 

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Really sounds like timing chain slap, but a timing chain slapping that loud is pretty uncommon. Considering the motor is running well, good compression and oil pressure, it does make sense to take a long look at the timing chain.

Either way, to solve this, you're gonna have to pull the valve cover and oil pan. Check the rocker assemblies, rod bearings, crank bearings, crankshaft end play, timing chain and chain tensioner. You can also rotate the crank while inspecting the each cylinder for for a piston rocking in the bore. If you think it's piston slap, you could start by sending a borescope down each spark plug hole to check for excessive cylinder wear.
 

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Ouch...sounds like something internal and not an exhaust leak. Really hard to tell from a vid clip, but Im guessing if you laid underneath you'd hear it even louder. To me it sounds like a rod knock.
 

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Discussion Starter #4
[/ATTACH][/ATTACH]


Finally dropped the oil pan and found these pieces at the bottom. Quick look up in Cylinder #6 I'm pretty sure they are part of the piston. It appears the bottom portion of the piston blasted off but still seems to be in tact up on top. I have zero experience in this area so.. yea. any idea if i'm on the right track here or what may be the next step. The engine is still attached to the jeep but I now have access to top, side, and bottom. Hoping to rebuild/replace what i can from here.

Note: the parts are super lightweight; aluminum.
 

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Discussion Starter #5
Note: top portion under the valve cover all looked tight. I brotated the engine a handful of times and everything seemed to be working well. One rocker has the slightest of side to side play which seemed different from the rest but after a quick 1/8in turn of the bolt it went away. When the knocking was happening it was deff. coming from the bottom.. pretty much in the exact spot i found the broken aluminum pieces.
 

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I’m sure someone will correct me if I’m wrong, but those look like piston skirts.
The skirts hang down the sides of the pistons, thus the name. The 4.0 is known for them breaking off.
The missing skirts will allow the “bad” piston to rotate, at some point, as the story goes.
Did you get a good look up the cylinders while you had the pan off? You should have been able to “see” the piston that was missing the skirts.


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Definitely piston skirt. From here the motor really needs to be rebuilt. Judging by the wear on the piece of broken skirt, the #6 cylinder is probably chewed up along with the rings on that piston. But hey, it's your motor. If after you pull the head and inspect the cylinder, you feel you can get away with just replacing the one piston, go for it. Nothing wrong with old dingleberry rebuild. Without much experience with engines however, you might wan't to call your local automotive machine shops.



 

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I had #1 piston skirt break in feb last year. three or four others had hairline cracks in them too so won't have been too far behind. I had parts shipped from rockauto to the UK and was back on the road in a fortnight. I noticed that the OEM pistons only have three small oil holes on front and back for oiling the rings. Most of these were almost totally blocked with carbon deposits (5K oil changes with syn oil).

My cylinder walls only needed a light hone, even #1 and driving about 60miles before parking at work for repairs. As it seemed one or two lifters were not oiling as well as the rest I thought I might as well change them whilst I was in there. And since I was going to do that, I decided to get a new stock grind cam too. Standard size pistons and rings were used as the cylinders were still in spec. I left all of the bearing shells in place as wear looked normal and oil pressure was good before the strip down.

My engine was at about 188k miles I think when that happened. In all I changed cam, lifters, rods, rockers and pistons. I ground and lapped all valves and fitted new seals. Changed the distributor too as there was a little play in the shaft and slight wear on the drive gear. I was able to do this at work, and got it done over weekends and an hour or two before shift start during the two weeks. I have a lot of tools already, but had to buy a few, and borrow a valve spring compressor. All in including the extra tools, and shipping of parts to the UK plus taxes, I was in for around £850 ~$1k.


#1 cylinder pictured below.
 

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Just got done doing a in Jeep rebuild. Mine was rattling but no piston skirts broken yet. If it were mine I would go ahead and pull the piston and check the cylinder for damage. If nothing you can catch a fingernail in, hone and new pistons for sure. Do them all, while you're there.
 

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Discussion Starter #10
Howdy guys, quick update on this one.

After reading everything on the forum and talking with a couple engine guys, I've decided to go ahead and purchase a new engine. No sense in spending upwards of $1000 bucks for a reasonable rebuild when a new motor is only double that right?!? Been picking up pop cans for the last two weeks and I think we should have enough to place the order today/tomorrow.

Three options so far and unfortunately they all seem to have 3-4 weeks estimated delivery times. Either way, here's the down and dirty. Any experience with these mfg. please add your input and/or recommendations as to which is best all around. I'm looking for zero modifications during install, long life/longevity, and as Jeep 4.0 as it gets.

Thanks again as always!

We have all very similar quotes from...
Powertrain APS-L4099JSF. (CID ENGINE...not sure what that means)
Fraser.. haven't actually gotten the part number here but it's a 4.0 I6 242 to match the Jeep.
ATK. Part # VA32
 

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No sense in spending upwards of $1000 bucks for a reasonable rebuild when a new motor is only double that right?!?
Maybe you can get lucky with one of the crate motor companies and verify the parts and specs of the motor. They're all rebuilt motors, and typically they're all built with the cheapest parts possible. If you had your local engine builder do it, you could scrap those weak factory pistons for Hypers, Clevite Bearings, Moly Rings, Melling Oil Pump & Timing Set & a Cam of your choice with a little more lift (for less $). Do you have a means of pulling and transporting your current motor?
 

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Discussion Starter #12
Yea I can do the swap in my driveway which seems to be the best option given my tool set and experience. This would be the third engine swap I've done in the past 20 years on various jeeps so pretty confident about the work at least. Main thing now is to make the purchase of the new motor. Just looking for any input on the three quotes I got. I'm pretty much over the rebuild route as the cost seemed a little too high in comparison to buying a professionally mfg. new one.
 

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Discussion Starter #13
ok... I reread your last.. makes sense. I'll ask around the local engine shops and see what they'd be willing to quote me on something like that. Basically have a trusted rebuild with quality parts over a reman crate engine right? if the costs work out and I could trust the work, I'm def. down for something like that.
thanks again.
Maybe you can get lucky with one of the crate motor companies and verify the parts and specs of the motor. They're all rebuilt motors, and typically they're all built with the cheapest parts possible. If you had your local engine builder do it, you could scrap those weak factory pistons for Hypers, Clevite Bearings, Moly Rings, Melling Oil Pump & Timing Set & a Cam of your choice with a little more lift (for less $). Do you have a means of pulling and transporting your current motor?
 

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Discussion Starter #14
Update and further questions...

I'm about 3 weeks into this engine swap.. went with a reman by Fraser (great service by the way.) took my time cleaning old parts scrubbing covers, bolts etc... Engine is sitting pretty on the mounts, trans is snug up and bolted in, just getting stuck on a few little here an theres but hopefully ready to start this thing up sometime before the weekend. Anxious and nervous of course, I'll get a video of the first turnover for you guys.

Questions..
what the heck is this and where does it go?
4424387


I have a few other loose parts and little bracket thingies, cant seem to find out what they were for and my initial video/pics of the engine bay weren't clear enough to see. Been diggin in the Haynes manual for now.

more part pictures to come. we can play a game of what is it and where does it go?

thanks!
 

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Discussion Starter #17
Got another one for you guys.. hoping to start er up today before the rains come. Down to the last few wiring connections, stick shift, one bolt left on the exhaust manifold, and maybe headlights if there's time. Anyhooo... Haynes manual says this wire is an engine ground, except it appears to have been attached to the transmission bell housing. Wondering what your thoughts are on that. here's a pic. Left side of engine near the oil dip stick and that sensor thing. Already tried looping it over the sensor but the bolt was too big so i'm pretty sure it wasn't originally attached there. have a look.

4425348
 

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I don't think being bolted to the bell housing would cause any issues with the amount of bolts holding the bell housing to the engine, but I think the proper location for those ground wires is the bolt holding the top of the dipstick tube.
 

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Here's my engine ground location on that side of the block. You can see two cables. One lead (think from the starter) and the other ground are attached to the same ground post.

4425693
 

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Discussion Starter #20
Here's my engine ground location on that side of the block. You can see two cables. One lead (think from the starter) and the other ground are attached to the same ground post.

View attachment 4425693
Well i'll be danged, mine wont reach all the way over there. I stuck it on the Bell Housing and so far no issues.
 
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