Freshen Up Motor Question

[XXLMJ]

I recently pulled a 4.0 renix motor out of an XJ. Its going into my 89 MJ, the motor has about 140k on it, runs fine. I was wanting some opinions on what i should do to it before i reinstall it. I was planning on new gaskets, water pump, oil pump, and timing kit. My main question is the main bearings, should i change them? Or wait til they need changed? And some were on this site i saw a post that said were to look on the motor to find out what size bearings to use. Thanks for and help.

[kro10000]

Personally I'd do bearings, but no matter what I would do the oil pump, get a melling HV

[jimoshel]

If there's nothing obviously wrong with it, oil leaks, low oil pressure, knock or rattle, I wouldn't touch it. Put it in as is.

[mnkyboy]

i wouldnt go any farther then a few gaskets and seals,the 4.0L is a leaker but at 140,000mi it should be mechanically sound

[Eagle]

I would do the bearings. They aren't that expensive, and it's a LOT easier to do them with the engine out of the vehicle and turned upside down on an engine stand.

[XXLMJ]

Wow thats some mixed answers, 50/50. What do you guys think about the timing gear? The oil pump goes with out question, its getting replaced. This is going to be my new daily driver so i would like it to be as problem free as possible, but i don't want to over do it, or replace stuff that doesn 't need to be.

[mnkyboy]

IMO 140k is still fairly low for a 4.0L mine has almost 100k more then yours and runs fine.

 

I would do things like valve cover gasket,main seals,and oil pan gasket then put it in. while you are in there you will be able to look for signs of metal shavings or crap build up from lack of maintenance.

[the_wizard_of_fire]

Wow thats some mixed answers, 50/50. What do you guys think about the timing gear? The oil pump goes with out question, its getting replaced. This is going to be my new daily driver so i would like it to be as problem free as possible, but i don't want to over do it, or replace stuff that doesn 't need to be.

my thought is while its out, replace everything you can afford to, because, yeah the parts there might be fine, but if you don't do it now, your gonna do it later, while the motor is installed.

[wyk]

Can one tell by how clean the top end is if it was well cared for if you removed the valve cover? Do you see a lot of carbon build up if it was run hot often and the oil not changed much? Is there sludge on the parts of the valve cover? I am wondering if there is an easy way to tell if the motor was at least abused, if not properly cared for.

[dasbrick]

What the guy said a little up, replace everything you can. Try to go high performance when you can as well. I've had experience that the stuff goes farther then OEM. Higher tolerances.