4.0 engine noise

Morks

Morks

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2004 jeep 4.0 engine noise... read lots about all possibilities, I've made a post about engine issues before... Was hydro-locked. Thought it was lifters, replaced all, and wasn't it, wanted to get in there and check out the engine anyways so was a good learning lesson. Popped the valve cover too, everything is getting lubricated with 0 noises, and when my head is close to where the oil pan meets the tranny (manual) I get the noise the loudest/ clearest. Going to check compression and see what that tells me. If compression checks out fine, I am assuming piston slap or a bad bearing but probably piston slap as there was no metal in oil so my best bet says it is not a bad bearing.

 
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Automatic? If so check your torque converter bolts, if there is an aluminum buildup on the bolt heads they're hitting the dust cover. Mine were hitting the dust cover and making a similar sound. Had to remove the trans to straighten out the cover and replaced the bolts. Be very careful with these bolts if they get replaced. They're a low head and a short thread. If you put a bolt that's threads are even 1/8" longer it will destroy your torque converter. (Ask me how I know... LOL)
 
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U8MYDZT said:
Automatic? If so check your torque converter bolts, if there is an aluminum buildup on the bolt heads they're hitting the dust cover. Mine were hitting the dust cover and making a similar sound. Had to remove the trans to straighten out the cover and replaced the bolts. Be very careful with these bolts if they get replaced. They're a low head and a short thread. If you put a bolt that's threads are even 1/8" longer it will destroy your torque converter. (Ask me how I know... LOL)
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Completely thought I added that it was manual, changing it now!
 
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These noise threads are fun, I say rod knock, seems too fast for valve noise. How does the noise change with temperature? Have you tried thicker oil? If you put heavy oil in it for a few miles I think it'll tell you bearings vs piston slap without taking anything apart and it'll only cost you a few quarts of oil.
 
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pagrey said:
These noise threads are fun, I say rod knock, seems too fast for valve noise. How does the noise change with temperature? Have you tried thicker oil? If you put heavy oil in it for a few miles I think it'll tell you bearings vs piston slap without taking anything apart and it'll only cost you a few quarts of oil.
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The noise stays the same with temp change, and yeah I switched from 10w 30 to some 15w 40, and no difference.
 
JKP said:
That would be my guess, the force required to bend the rod would also damage the bearing.
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Have been under the jeep with the oil pan off twice since hydro lock and everything looked ok before which is why I have ruled out rod knock! However, my oil pressure is lowish. Going to take the oil pan off soon and see if anything has changed as well throw in a new oil pump.
 
JKP said:
Check out this guys carnage:

Low oil pressure indicates the bearings are going.
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Now would it be worth it to throw some rod and main bearings in it, look for some piston issues if nothing slap it together, and run it till she dies kinda deal...
 
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Probably.

As he stated, the pistons come up in pairs, 1 and 6, 2 and 5, 3 and 4.

So, you might have 2 bent rods.

Bearings should be fairly cheap.
 
Morks said:
Have been under the jeep with the oil pan off twice since hydro lock and everything looked ok
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I would be well into the "ignore it" category at this point. If you have oil pressure and the rods didn't move I'd forget all about it until a rod shoots through the block. It's a tractor, it'll be fine.
 
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JKP said:
Probably.

As he stated, the pistons come up in pairs, 1 and 6, 2 and 5, 3 and 4.

So, you might have 2 bent rods.

Bearings should be fairly cheap.
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Yeah, everything is pretty cheap for it bearings, connecting rods etc... Going to tear off the oil pan again tomorrow and ill update the thread with some pics of what I find!
 
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pagrey said:
I would be well into the "ignore it" category at this point. If you have oil pressure and the rods didn't move I'd forget all about it until a rod shoots through the block. It's a tractor, it'll be fine.
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That's been my thought lol
 
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JKP said:
Probably.

As he stated, the pistons come up in pairs, 1 and 6, 2 and 5, 3 and 4.

So, you might have 2 bent rods.

Bearings should be fairly cheap.
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The rod knock should have started way before though, shouldn't it? Hydro locked it almost a yr ago now...
 
JKP said:
Broken piston skirt(s), bad bearings, bent rods. Could be any of those at this pt.
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pagrey said:
Nawwww.
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Well, popped injector plugs off when the jeep was running no noise change on any of the cylinders, compression was all withing spec 142 the lowest 155 the highest... Going to be raining here the next couple of days and driveway work is no fun in that. Hopefully have the oil pan off soon and I will update the thread.
 
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