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OverlandXJ 09-16-2013 01:28 AM

Rebuild VS Replace '99 4.0L in an XJ
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Hey there,

I'm at a crossroad with my Jeep where I need to either rebuild or replace the engine.

My 1999 XJ has 275,000 original miles on the engine. 8 hours from completing a 10,000 mile road trip around the US I blew the head gasket and broke something metallic inside, presumably push rods. The engine died without warning while going about 65mph along an interstate, there were no common signs of bad engine voodoo.

I haven't tore down the engine yet but I can only turn the flywheel about 1/4 turn when I hear a metal clunking sounds and then the flywheel stops.

Is it worth rebuilding an engine with that high of mileage or would I be better off getting a crate engine?

Also, should I rebuild the tranny while I'm at it and have the engine out? Will I run into any common problems with a rebuilt or zero time engine mounted to a high mileage tranny? Are there any higher performance or stronger trannies?

How complicated is it to rebuild a tranny?

Does anyone have personal experience and opinions with any of the following crate engines in their jeep (not to be confused about anything you've read or heard someone else talk about ):

If I rebuild, this will be my first rebuild project. Likewise if I do the install, this is the first time I'll be working on a complete engine. I wouldn't say I'm a mechanic by any means, but I can read and follow directions pretty well and do most of my own maintenance.

I appreciate any insight you might have to offer.

Be well.

LimeLJ 09-16-2013 02:24 AM

The only to tell if the block is worth rebuilding is to tear it apart. If a connecting rod has broke and has slammed into the piston wall it may be fatally wounded.

As for the various crate engine companies every has reported good and bad experiences with them. There is really no definitive answer there other than go with the one that has the best warranty and customer service.

sAe23 09-16-2013 02:28 AM

Assuming the core is rebuild-able, the mileage isn't a factor.
If you pay a shop to rebuild it, figure it'll cost up-wards of $2200 (including removing/re-installing the engine).
If you have the shop space, tools and the desire to do it yourself it'll cost a lot less.
Crate engines will run $3000 to $5000 but you can choose how much power it'll make.
As for the transmission, if it was running OK and was properly serviced, I'd leave it alone.

SaarXJ 09-16-2013 04:56 AM

Usually, I think rebuilding the engine will give the best results - if it had been done by the book.
(meaning, replacing everything that should be replaced...)
But you will know if that is possible only after checking the current engine.


AZ Jeff 09-16-2013 07:54 AM

If you broke a connecting rod, there is a real chance the crankshaft is bent due to the uneven load and/or the pounding of the broken rod on internal surfaces of the crankcase.

A bent crank cannot generally be straightened by grinding sufficiently to insure the journals can be ground true again. The crankshaft is trashed.

Once you factor in a new crank into your build costs, its pretty easy to see that a new (reman) engine, or at least a new (reman) "short block" is your best bet.

OverlandXJ 09-17-2013 10:15 AM

I appreciate the insight folks. The consistency in your statements sends a pretty clear idea.
I do have time and shop space so I may do the full tear down and investigate further.

The time now is 01:55 AM.

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