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Input on replacement motor

W

whatwave

NAXJA Forum User
Location
Colorado
Sadly, at only 130,000 miles I have a cracked piston ring and my motor is dying a slow death. My buddy and I are looking to swap in a replacement motor this winter. My mechanic suggested a Jasper reman but it doesn't look like they sell to the public. I'm hoping you guys could give me some thoughts on what my best bet is. I'd like to keep cost of the motor under $4,000 and I intend on keeping this vehicle forever (or until I do something stupid and destroy it wheeling). I'm not opposed to a stroker but I'm my overwhelming priority is reliability.

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4k for a stock replacement!? Holy crap. I gave 300 bucks for my junkyard motor, a set of valve stem seals is all I've needed in 50k miles. If I get around to putting a set of rod bearings in it will probably last forever. I have a stroker crank for sale if you choose to build your own.
 
If you don't need to be back on the road this week, find a low miles used 4.0L. It will bettter than any store bought rebuild. Use the motor you have for your stroker build.
 
Tim_MN said:
Use the motor you have for your stroker build.
Click to expand...

So this is interesting if I could find a shop to do it. My concern is just finding a place that does quality work. Any suggestions on finding a reputable shop? I'm in Denver if it helps.

On finding a low mileage motor, that seems like a tall order.

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Unclewolverine said:
4k for a stock replacement!? Holy crap. I gave 300 bucks for my junkyard motor, a set of valve stem seals is all I've needed in 50k miles. If I get around to putting a set of rod bearings in it will probably last forever. I have a stroker crank for sale if you choose to build your own.
Click to expand...
I don't feel competent to build a motor on my own. And I want this thing to just run for at least another 100k, hopefully more. So I hate to drop in a high mileage boneyard motor. My shop said the Jasper reman would cost me $3,500, I'm kind of basing prices on that. Their quote was pre-Covid so I assume things are more expensive now.

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Get acquainted with your local chapter. There are a bunch of folks in the Denver area. If you are local some of them might be friendly, maybe even helpful.

Building a motor isn't rocket surgery. It is mostly a matter of cleanliness and attention to detail. If you can manage those skills you can build a motor. An engine hoist and an engine stand can be had used off Craigslist, but you should plan on spending real money for a good quality torque wrench. And probably get a size specific ring compressor once you know your exact bore size. Beyond that you just need a space to work in.

One way to approach this would be to purchase a used motor from a junkyard and rebuild it (or refresh it) yourself with the idea that you are using it to learn the process so you will know what to do in order to build your stroker. Youtube can educate you enough to get you on your way. Even better if you can find a local to help you along.
 
Check with your local speed shops there, they would know all the reputable shops.
 
whatwave said:
On finding a low mileage motor, that seems like a tall order.
Click to expand...



Try www.car-part.com. Any XJ or ZJ will bolt in. Super low miles are not as common as back in the day, but there are several at about 100,000 near me. One yard has a motor with 52, 000.

Remove and re-use ( or replace with new ) as needed or required from your original engine: Intake/Exhaust manifolds, motor mounts, throttle body, fuel injector rail, flex plate/flywheel, cylinder head, water pump, distributor-less ignition or distributor assembly, OBD engine computer sensors, fan belt driven accessories, and/or mounting brackets.
 
Last edited:
Oh wow. I was envisioning buying one from the boneyard with unknown miles. Definitely going this route. Thanks!

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Yeah, car part is where I found mine, like I said 180k miles, $300. Find one with ~100k, pop in a set of main bearings, put in set of valve seals or better yet, take off the head and have it rebuilt you will be ahead of a jasper rebuild. Quality is not job #1 with aftermarket rebuilders.
 
Unclewolverine said:
Yeah, car part is where I found mine, like I said 180k miles, $300. Find one with ~100k, pop in a set of main bearings, put in set of valve seals or better yet, take off the head and have it rebuilt you will be ahead of a jasper rebuild. Quality is not job #1 with aftermarket rebuilders.
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I found one with 73k for a grand. Had the VIN attached so I was able to look it up, out of a four owner car. Said screw it and pulled the trigger.

You think I should do some work to this engine before installing?

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Nothing more than a oil change until you can evaluate what you bought!
 
You should replace the front and rear main seal, pan gasket, and timing cover gasket. Check the rod bearings and timing chain while you have the cover off. Use right stuff gasket maker instead of gaskets.
 
I'd also replace the harmonic balancer. $50. I use gaskets, but I also apply a sealer to them. I like to use Holymar type. Then the gaskets sort of peal off, if you need to tear into things again.
 
Where in Colorado are you? My home is in Loveland. I will be back in Colorado more and would be happy to help you find a good used engine. A straight swap can be done in a day if you have a couple of guys. We could probably get a group over to hit it and have some bbq. We used to do that kind of thing all the time.
 
Also plan to replace the O-rings for the oil filter adapter while you can access that big torx with a proper ratchet or breaker bar.
 
So, how did you determine you have a crack piston ring? X2 on doing the oil filter adapter while you have easy access. Replace motor mounts if they're still original.

Take Old-Man up on his offer! Nothing like having someone who has done it before on tap, even if they sit back with a beer and just supervise. Having someone ask the little questions like, "you made sure the t/c was fully seated right?" is invaluable.
 
lawsoncl said:
So, how did you determine you have a crack piston ring? X2 on doing the oil filter adapter while you have easy access. Replace motor mounts if they're still original.

Take Old-Man up on his offer! Nothing like having someone who has done it before on tap, even if they sit back with a beer and just supervise. Having someone ask the little questions like, "you made sure the t/c was fully seated right?" is invaluable.
Click to expand...
Among other things, the mechanic used and endoscope. This happened well over a year ago so unfortunately I'm hazy on the details at this point.

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I'm curious what you ended up doing? I've been looking at "remanufactured" engines but they don't get a lot of good reviews.
 
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