lakebrooks10

Anyone on here have any experience rebuilding the 4.0 that came in the 96 xj? I picked up this ride and it has a few rattles and leaks a fair amount. Thought about just snatching it out and rebuilding for my own best interest. Any tips on rotating assemblies?

5-Speed

Rebuilding is easy and cheap. If you can afford to have the Jeep down for a little, just reuse the rotating assembly thats already in the engine (at least have the crank polished and if bad, turned). If it runs currently, it should be reusable.

lakebrooks10

Just have the block machined and let er rip?

5-Speed

Thats about it. I just rebuilt mine from top to bottom and it was around $500 in parts. Then you just have to get the machine work done and slap it back together.

lakebrooks10

Sweet. Thanks for the info.

5-Speed

Ill be doing a write up on the whole rebuilt process. Not sure when but should be soon. Should help you out when you get to that point.

mannydantyla

How many miles on the engine?

Do a compression test. Spec is 120-150 psi, don't forget to press the gas pedal to the floor while cranking (gets more air into cylinders and also keeps the fuel injectors from flooding the engine because the ECU is in "clear flood mode" with gas pedal on the floor when cranking). My engine has 255,000 miles and I just did this test and all 6 where 140-150 psi.

If the compression numbers are good, consider an overhaul rather then a full rebuild. Drop the head off at a good machine shop. New head gasket, new timing chain set. Leave the block in the vehicle, just get underneath it and pull the oil pan. Clean the oil pump, replace the seals, and inspect the cam shaft and rod clearances and stuff.

That's what I would do.

Bugout4x4

"rotating assemblies" Are you talking about that turny thingy that makes it go?

steelybill

Bugout4x4

Maybe I should not have done that... I will think twice next time. lol