lpresnell

Hey Guys, 1st post. Have a 2000 Grand Cherokee with 4.0 that blew up at 256,000 miles. Bought another engine with 102,000, but do not feel comfortable installing without a rebuild. Any suggestions?
Thanks, Larry

JPXJMOAB

Tear into it.. Get it apart, send the heads and block to a machine shop and get them checked for cracks and decked. Inspect all the push rods for damage/bends. If they need to machine out the cylinders, the machine shop will usually hang the Pistons for you.. What advice are you looking for?

lpresnell

Should I get a new head? Just don't what to do. I will find a good machine shop. Don't want to take any shortcuts. What head is the best. I use this to tow a camper trailer. Should the clearances be tighter? Just not a mechanic!

JPXJMOAB

I would recommend having the machine shop inspect the head before you even begin looking for a new one. With 100k miles in sure it's okay. Otherwise I'd check out Clearwater cylinder heads. As for the clearances I would leave them the same as stock. If you'll be towing a lot just add a tranny cooler.

Fred/N0AZZ

Hello Larry and welcome to the forum!


A lot depends on the overall shape of your Jeep in general? If all else is good and body in decent shape then a rebuild is in order if you plan on keeping it for a while.


Take it to a good machine shop/engine builder and tear it down and check everything. Make sure they are aware of the problems with the heads on the 4.0's and address it first if needed. Then do a full rebuild with new pistons and other needed new items. If the rebuild is done properly with good parts it should run for another 250,000 or more mi.


A rebuilt engine amounts to the quality of the parts and skill of the rebuilder. That is why I never buy a rebuilt engine from a supplier you never know what your going to get with parts of quality of labor.

dave1123

Hey, Fred! That's why I rebuilt my own! Being a toolmaker, the only machine I didn't have access to was a crankshaft lathe. The trick to rebuilding engines (or anything) is attention to detail. Too many shops are focused on the bottom line, time and money. For the most part, racing shops do the best work but getting them to take on a stock rebuild can be a problem.

Back in the 50's, Sears Roebuck sold replacement engines installed for a good price. Amazingly, they were reliable.

Today, I'd have to say buy a crate engine from Summit or the dealer.

You are correct in saying a proper rebuild should last as long as the original.

bigbadon

Why rebuild if it is not necessary? I would inspect the engine first:

1. Pull the oil pan and check bearing clearances
2. replace rear main seal
3. check crank end play
4. inspect or replace oil pump
5. measure pushrod lift with dial indicator
6. do a cylinder leak down test
7. bore scope the cylinders to see what they look like
8. pull cam position sensor and rotate crank to measure timing chain slack/wear

IMO I would trust a well maintained 100k 4.0 engine over a budget rebuild.

lpresnell

What new head should I get, as I am not installing the old head? Was going to get an Edelbrock until I saw the price. No way on that.
Thanks

JPXJMOAB

Clearwater cylinder heads. Many guys here use them including me and they're a great quality new head

Fred/N0AZZ

Yes it is harder to find quality work any more, I use 2 different shops for my rebuilds Hatfield Racing Engines and BW Machine/Racing Engines. I do buy the major parts that I want used in the builds.


Like I said I want quality work, that's why I don't do it myself 8>)


Don I agree if the OP is comfortable with that, my main question is always "How Well it Was Maintained" very hard to tell at times. But for sure the cheapest way to go and if it is in good shape should go a lot more miles.

lpresnell

Think I got lied to about the engine. Took valve cover off & never have I seen such sludge. Has to have 200,000 miles or more! Gonna rebuild with a new head, almost new everything. New pistons, bearings, everything. Is the
Quadratec head any good?

dave1123

Yup! Got one on mine. $455 complete with valves and shipping BOTH ways (core return), guaranteed 5 years. Google "Clearwater Cylinders Heads" or call 727-299-9058.

bigbadon

You bought a dog of an engine! There are good used engines to be found but you have to inspect BEFORE you buy. A good salvage yard will "hot test" the engine,give a warranty and give you the vehicle VIN# which allows you to search dealer service records for free. You can also pay to use Carfax.

Fred/N0AZZ

Sad fact anymore, "believe nothing you hear and half of what you see"