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View Poll Results: What is the most likely cause of my engine troubles? (No audio yet, sorry)
Piston slap
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20.00%
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40.00%
Rod knock
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40.00%
Timing chain
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1998 xj issues

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Old 01-02-2021 | 07:23 PM
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Piston weight according to 1998 zj and tj service manual.
Old 01-03-2021 | 06:49 AM
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Originally Posted by Dave51
Cause piston weight specifications are w/o the pin. 1998 should be 563 - 567 grams w/o the pin which, if you measured the stock piston w/o the pin is right on target.
93,94,96,97and 98 FSM (couldn't find a 95) have a piston weight(less pin) of 563-567 grams
https://www.jeepstrokers.com/forum/viewtopic.php?t=271

but the parts manual shows



so it seems to me the breakpoint is 98 not 99.

5302 0507
is the metric version of 4798 329.

The new pistons are 12 grams over upper limit (but over 100 grams less than the earlier design).

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Old 01-03-2021 | 06:59 AM
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Originally Posted by Mildphil
I don't know if I should just return the pistons or grind them down, but that's way out of spec.
Contact Sealed Power:

https://www.drivparts.com/fmstorefro...Contact%20Form

But frankly I'm not seeing where you can grind off 12 grams of material safely; justify the expense; for what ultimate purpose since this will never be a racing engine; and this a short term engine anyway.
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Old 01-03-2021 | 08:00 AM
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Originally Posted by Dave51
Contact Sealed Power:

https://www.drivparts.com/fmstorefro...Contact%20Form

But frankly I'm not seeing where you can grind off 12 grams of material safely; justify the expense; for what ultimate purpose since this will never be a racing engine; and this a short term engine anyway.
The sealed power are the pistons I just ordered, it was the enginetech which were out of spec. I've already ordered the correct set of sealed power pistons (which should be here in a few days). I figured it was too much to grind based on the fact that the huge broken piece of piston skirt was barely 20 grams! Thank you for all your help so far Dave, I think I would have gotten myself into some trouble far sooner had you not kept with the thread and continued to provide your valuable info!
Old 01-05-2021 | 02:20 PM
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While waiting on the pistons I've done the rear main seal (the bearing of which was in good shape), oil pump, and prettied up the old ugly rims. Also happened to find my magnet stick in my truck and checked out the lifters, they were also in great shape!

Pulled a few lifters, all lookes similar to this.

Before

After
Old 01-06-2021 | 08:29 PM
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So my new Sealed pro pistons weigh ~435 less pin(6 grams over), but with pin are ~557(6 grams under). Is this safe to run?

Last edited by Mildphil; 01-06-2021 at 09:29 PM.
Old 01-11-2021 | 05:03 PM
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Engine is back together, I recorded how it sounds




Last edited by Mildphil; 01-11-2021 at 05:05 PM.
Old 01-11-2021 | 05:06 PM
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Old 01-11-2021 | 06:22 PM
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Love that oil pressure. Sounds smooth re: the whole combustion process.

On my speakers I'm hearing a pronounced click. Like an uncooperative lifter. Maybe exhaust leak but more like a lifter.

Or maybe water pump racket?
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Old 01-11-2021 | 06:51 PM
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Originally Posted by Dave51
Love that oil pressure. Sounds smooth re: the whole combustion process.

On my speakers I'm hearing a pronounced click. Like an uncooperative lifter. Maybe exhaust leak but more like a lifter.

Or maybe water pump racket?
I'm not exactly sure what it is, I was thinking exhaust as well. Could be the bolts aren't tight enough? I tightened the ones I could easily reach to 25ft/lbs, the rest got the ol german treatment. It's actually driving me absolutely insane that it's making that tick sound which wasn't present before. It could also be possible I cracked the manifold while moving it around? I'll make more videos in specific areas when it's daytime.
Old 01-11-2021 | 07:21 PM
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Also while the head was off, I removed all the lifters, cleaned them (carbon and junk from the headmaster had fallen on them), soaked them in oil, and then applied assembly lube. Also when I did the timing chain, I did spin the water pump pulley around a bit and it felt fine. Could it be possible I tightened the serpentine belt too much?
Old 01-11-2021 | 07:26 PM
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Here are just some general pics from the rebuild process






Old 01-11-2021 | 07:42 PM
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Use the German method on the intake/exhaust fasteners. 25 is too low.
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Old 01-12-2021 | 08:36 AM
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Alright I'll try cranking them down, I wouldn't doubt if some didn't get the full torque, they are so hard to reach under the intake! The more I listen to the videos, the more it sounds like lifter noise (which I don't recall it making before). What could cause this? How should I treat it (assuming it is lifter noise)?
Old 01-12-2021 | 06:14 PM
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Tried tightening the exhaust/intake and nothing happened. Also before the rebuild, the car had a nasty gas fume smell which it still has now. So assuming it is a lifter(s), what would be the best thing to do?



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