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Old November 1st, 2003, 08:13
Bender Bender is offline
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Swapping used engine..what should I check?

I had a mishap with some water that rendered my engine useless. Snorkel worked great but I was underwater for a long time with the jeep running and the drink slowly seeped past the seals into the crankcase killing my cam, main bearings, and piston rings. So, I need to put in a replacement. I have a spare engine with 100k miles on it but the service life of this engine is unknown.

As to address common issues while the engine is easily accessible I have decided to chance the oil pan gasket, timing cover gasket, rear main seal, intake gasket replacing the currently cracked exhaust manifild with an uncracked unit, as well as the valve cover gasket.

Some questions though...

How do I tell if the timing chain is alright? I've never heard of problems with these at 100k but I figured I should check it anyway.

How do I know if there is too much wear on the cylinder walls?

If I take each rocker off and remove the pushrod one at a time to clean them will this affect anything? I'd reinstall before removing the next.

How sould I reintall this stuff...with a little layer of clean motor oil?

Is there anything else I should do while I'm in there?

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Old November 1st, 2003, 15:40
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Eagle Eagle is offline
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FSM allows 1/2" of slack in the timing chain. I replaced mine as a pre-emptive strike at somewhere around 200,000 and it was as tight as the new one.

Don't worry about wear on the cylinder walls. 100k (miles) is nothing on these engines.
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Old November 1st, 2003, 18:42
HossHoffer HossHoffer is offline
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Motor oil is not the best for those gaskets you mentioned. NAPA or other stores have gasket sealant/adhesive. The intake/exhast gasket goes in dry and the main seal goes in with oil, soap and rtv.
As far as cleaning each rocker and pushrod, there are cleaners you can run with the oil or just use solvent with them in place. If you really have sludge up top then kerosene takes it out but be careful with it because if you leave any in, it will break your oil down.
When you get the new oil pan gasket get the one piece gasket.
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Old November 1st, 2003, 19:30
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sidriptide sidriptide is offline
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while its apart dont forget to clean out all the passages for the CCV system (the breather tubes on top of the valve cover..) when i did mine the inside of the engine had a lot of crusty carbon-like build up.. not sludge... carb cleaner wiped alot of this away.. i assume that is why you want to clean your push rods.. a rag soaked with it should clean them up.. if the engine ran well before you got it i would not open up the cylinder head to inspect it... you can get a good idea of any abmormal wear looking up into the cylinder from the bottom.. that is were a 4.0L will wear most anyways.. the botom of the cylinder takes a tremendous side load at the begining of the upward stroke.... 100K on a 4.0L is not a big concern... just do all the gaskets and seals properly and enjoy....
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