How many miles is too many?

I have a line on a pretty well built XJ with over 220,000 miles. I know the 4.0 is bullet-proof, but to what extent? It sounds like nothings leaking on this rig, but is compression something i need to worry about? If so, how difficult is it to do a straight 4.0 swap? I know there are a bunch of 4.0's sitting in the yard.

Just wondering if i should steer clear of the 200+ club.

BTW, this is a 4.0HO

Thanks

I have a 88 4.0L Renix and it has great power. Also just turned over 250000 miles. Look for rust on the floor pans and above the muffler. Check all the mounts and such. If the engine sounds good and it has power in it then it will last for a little while longer at least. Pull the airbox cover and see if there is any oil in it that will tell you if you have a blow by problem.

My '89 has 260,000 on the clock...no compression problems yet. I'd say, pay what it's worth...not a penny more. The 4.0 is a strong motor and will go a long ways, but how much is really left at that mileage? Figure $3,000 minimum rebuild...up to $6,000 if you want a stroker. Figure it into the price.

I've got an 88 with 280K or so on the clock. It's been through transmissions (started life with a Peugeot, and I've been through four of them!) but the engine is still rock solid.

I'd say it depends on the year - newer ones are going to be less durable due to changes in the casting pattern (made lighter, usually) and mateials (reduced nickel content in the iron.) I'd like to have an assay done on the RENIX casting iron - that stuff is tougher than the hinges of Hell. My 87 lost an oil pump at 230K or so - when I rebuilt the engine, the top cylinder ridge was .0005" (Yes, I measured it. Three times. I couldn't believe it either - "Big 3" engines at that stage typically need to be punched +.010" to clean them up...)

I'll bore/stroke the engine later, and I'll look forward to putting a "Million Mile Plaque" on it some years from now. No reason to get rid of the thing, and no-body makes anything new I like...

Flyfisher said:

Figure $3,000 minimum rebuild...up to $6,000 if you want a stroker. Figure it into the price.

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$3,000 FOR A REBUILD??? I have just rebuilt mine. I had all of the machine work completed at a top shop. I replaced everything. Pistons, rods, crank, cam, valves, valves springs, lifters. Enerything was replaced except for the block and the head, which both were machined and I only spent a little over $1200.

I have a friend who drives a 96 2wd as his company vehicle. 340,000 with original motor/trans. Still runs great, hardly burns oil, but it definatly leaks though. Mostly highway miles, his company used to have a branch in Texas, many, many trips back and forth...