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turdhurdler 08-28-2010 03:38 PM

Rebuild or replace 4.0
It has come time to either rebuild or replace my 4.0 for my 93 YJ. It is using excessive oil and when I changed out my rear main seal a while back, I recall finding sizable metal pieces in the oil pan. There is no oil at all where I park the Jeep.

While doing my search, it appears that the pistons/cyclinders have gotten worn past tolerances. I don't appear to be burning any oil, so I don't think it is my valves going out.

So, my delima is this. Do you think it is better to try and rebuild the 4.0 with 163K on the clock, or step up and look into a remanned engine with a warranty? Like everyone else, my budget is tight. I have access to all necessary tools and knowledgable people to help me out. I just dont want to do a rebuild if it actually needs more to make it right.

Thank you in advance for your time reading my posting and any responses you may have.


GroundHawg 08-28-2010 05:43 PM

if you've got the money, do the 350 swap. I'd prefer that than a remanufactured 4.0 or 4.2. if that's not an option I'd repair the current engine.

I don't know the cost of all the options, but I'd check out those 3 motors, the cost of the current repair, then weigh the pros of each vs. financial allowance.

derekshep 08-28-2010 06:06 PM

4.6l stroked I6 long block-- swap over covers from old motor

turdhurdler 08-28-2010 07:33 PM

The above ideas are very inticing, but I live in CA and we have one of the strongest smog restriction laws. I am pretty much stuck with the stock replacement without getting into a lot of extra money and red tape.


H2_recoveryteam 08-29-2010 03:30 AM

Im in the process of the same delima with my 94 YJ except mine is a 2.5l. I also live in ca. So im in the same boat. Ive been doing a LOT of weighing my options and a ton of reserch and the route ive decieded to go is live with my 4 banger and do a complete rebuild on the engine. The only real advice i have is call around for the best price on parts and labor if you have someone do it. And spend the extra cash to replace the front end to like water pump thermostat, radiator. Ect. I think the rebuild is the easyiest fastest way to get our jeeps on the road again and reliable. Hope this helps.

Shadeemry 08-29-2010 03:51 AM

I vote rebuild. The sizable metal chunks may be an oil compression ring that gave up the ghost on one or more cylinders. You can further see this by looking at the air filter. Is it oil soaked? Or trace your finger around the throttle body intake where the air filter connects and see if you pick up oil. If that's the case, worse scenario is you will have to have your cylinder heads re sleeved by a machine shop because they will have groves from a broken ring in them ( or a junk yard pull for the cylinder head. usually what I do and cheap) and all your piston rings will need to be replaced.

turdhurdler 08-29-2010 11:36 AM

Here is some more info on what I have going on. The Jeep runs like a top, so I think it is going to be on the top end of the motor that is giving me the hassle. I hope to pull the plugs and do a compression test in the next day or two, depending on how busy work is for me. If I am lucky, I should be able to do a simple head swap. Thank you everyone for the feedback.


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