Crate motor suggestions?

[kzrider]

So I did a search on “crate motor” and most if not all posts are not very recent. It’s time to replace or rebuild my 97 4.0 and with almost 250k miles on it I have decided to replace the motor and not rebuild. It has a rebuilt 32RH and recent replacement of the ARB/ revolution axles in the rear. Frame and tub are in very good shape so I’m going to keep it till I can’t get in it anymore.

Looking for recommendations on a replacement. I see Frazier/ Summit (VGE?) and some others. Not interested in a stroker/ performance motor as I’m happy with stock power. Thanks in advance

 

[Moglocker]

So I did a search on “crate motor” and most if not all posts are not very recent. It’s time to replace or rebuild my 97 4.0 and with almost 250k miles on it I have decided to replace the motor and not rebuild. It has a rebuilt 32RH and recent replacement of the ARB/ revolution axles in the rear. Frame and tub are in very good shape so I’m going to keep it till I can’t get in it anymore.

Looking for recommendations on a replacement. I see Frazier/ Summit (VGE?) and some others. Not interested in a stroker/ performance motor as I’m happy with stock power. Thanks in advance

Titan,here in Florida

 

[sab]

If, by "Frazier", you mean Fraser Engines in Fraser, Michigan, run, don't walk, away from them! My experience with one of their engines (a Ford Triton, not a Jeep 4.0L) was about as horrible an experience as one could imagine. I spent $12k dealing with their crap before that vehicle was usable. For details, see my previous post in a similar thread about a year ago:

Post in thread 'Remanufactured 4.0 engines'

May 16, 2025

I got mine from Frasier engines....not had any issues so far but then I'm only 2,000 miles on it

If you mean Fraser Engines, out of Fraser, Michigan, then I hope you have better luck than I did. I have nothing good to say about those shysters. The short version of my story (yup, this is the short version!) is that I was stranded in Colorado due to engine troubles in my 2001 Ford Expedition about five years ago. Normally, I would have done the work myself in my shop, but since I was several states away from home, I paid a local Arvada shop to put a rebuilt 5.4L in it for...

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[macleanflood]

I bought a XJ block from a 97 and spent a few months building a stroker and swapped it in.

You can tear down your block...have a machine shop deck the head and block, check the cylinders and pretty much slap in new pistons, bearings, etc and be back in business.

I highly recommend this path.

Look at DeXJs on YouTube for some great down and dirty 4.0 refreshes.

-Mac

 

[jeepguy03]

I bought a XJ block from a 97 and spent a few months building a stroker and swapped it in.

You can tear down your block...have a machine shop deck the head and block, check the cylinders and pretty much slap in new pistons, bearings, etc and be back in business.

I highly recommend this path.

Look at DeXJs on YouTube for some great down and dirty 4.0 refreshes.

-Mac

I second this.

If you don't have the time to rebuild, then it might be worthwhile to find a used 4.0 with less miles to just swap in. I trust an OEM built used engine over a lot of the reman engines. I have a relative that bought a 5.3 V8 for his Chevy from Jasper and had a shop install it because he needed the truck and didn't have time to rebuild the engine. Well he went through 3 of those rebuilt 5.3s before he got a good one, or at least one that lasted more than a few months. In the end he probably had more time with the truck down due to it going back and forth to the shop.

 

[MtPockets]

X2 on the mistrust of a factory "rebuilt" engine.
If it were me, as long as yours is still running- buy a used engine and take it to a good local shop for a quality rebuild.
Factory rebuilds are done with speed in mind, NOT quality!?

 

[Daryl]

“Factory” rebuilds are done by the lowest bidder.

 

[Rickyd]

I second this.

If you don't have the time to rebuild, then it might be worthwhile to find a used 4.0 with less miles to just swap in. I trust an OEM built used engine over a lot of the reman engines. I have a relative that bought a 5.3 V8 for his Chevy from Jasper and had a shop install it because he needed the truck and didn't have time to rebuild the engine. Well he went through 3 of those rebuilt 5.3s before he got a good one, or at least one that lasted more than a few months. In the end he probably had more time with the truck down due to it going back and forth to the shop.

Do you know what kept failing on them?

 

[GoldenGorilla]

So I did a search on “crate motor” and most if not all posts are not very recent. It’s time to replace or rebuild my 97 4.0 and with almost 250k miles on it I have decided to replace the motor and not rebuild. It has a rebuilt 32RH and recent replacement of the ARB/ revolution axles in the rear. Frame and tub are in very good shape so I’m going to keep it till I can’t get in it anymore.

Looking for recommendations on a replacement. I see Frazier/ Summit (VGE?) and some others. Not interested in a stroker/ performance motor as I’m happy with stock power. Thanks in advance

I'm curious if there a specific symptom causing you to go with a new motor.

If you absolutely want to stay 4.0L, I'd really consider having a good local machine shop prep the block for you. Clegg offers good quality rebuild kits for the 4.0L in addition to their 4.6 and 5.0 stroker kits. Modern pistons address problems in the skirt and wristpins on 4.0Ls and the metric rings have less friction and work better overall if the 97s still had the taller SAE ones. That breakover may have only affected XJs/ZJs.

Have the machine shop deck the block. The 4.0L factory setup is actually more prone to detonation because of the excessive piston to head distance. It'll feel a little more lively with the slight bump in compression, but won't require any tuning mods.

Have them refresh the iron head and check that it's flat and has no cracks if not using your known good head.

Cam and lifters are tricky right now. If the cam and lifters have good wear patterns and are not worn out, the married lifters and cam are probably a better bet than a new cam unless you are going to a roller cam. There were rumors that Comp pulled all the later 4.0 cams. They have been unavailable for over 6 months. Flat tappet cam failures are affecting around 1/4 of the new 4.0 cams by many reports and will wipe out the crank and rod bearings in a new rebuilt motor. You can go roller cam now to absolutely avoid it, but plan to add 2k to your budget.