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Can i just replace bearings??

J

Jimminyc

NAXJA Forum User
Location
GJ, Colorado
Well, the stuff in my oil turned out to be copper. So, i pulled the pan and the mains are into the next layer of silver but no copper. Then the first rod bearing i pulled, was into copper. I was told i could just replace bearings with the motor in the jeep and get another 100k out of it. I have heard of people doing this, but i havnet heard of it working. I can sort of fell grooves on the crank with my fingernail. Anyway, it wasnt smoking, or knocking when i pulled the pan. But, i dont want to waste my time on bearings if i just need to find a good used 4.0 and put it in. Any feedback??
 
Langer1 is pretty much right. I've done bearings in that case, but only to get a few thousand more miles while getting another motor together. I lapped the journal with a leather strap and some cerium oxide. I ended up going to slightly undersized bearing as well.
 
If you feel grooves, it's time for a crank kit.

It's possible to change the crankshaft with the engine in place, but you'll have to pull the transmission (and lay it on the ground) to do it.

Once you've scored the crank journals (that's what's happened here, and why you feel grooves,) any new bearings you put in will get munched right away. Not worth the effort - unless you do the whole job all at once.

5-90
 
What is grooved the crank or the rod bearings? Any straw or blue colored patches on the crank?
Pasti guage will tell you how much actuall wear you have and how deep the grooves are. Plasti gauge is cheap, but takes a lot of time.
I've seen some old 4.2's that had some really sorry looking main bearings, that were still going strong.
The trouble with putting a new bearing on a scored crank is the high spots don't transmit the friction heat away fast enough and things have a tendancy to overheat.
 
Last edited:
yea, i think that i might be better off finding a motor. I didnt see any discolorations though. it wasnt overheating as far as i could tell. the only problem it has had is since its been cold, it would tick for about 6 seconds before pumping pressure up, and when it was hot it idled at about 20psi.
 
Jimminyc said:
yea, i think that i might be better off finding a motor. I didnt see any discolorations though. it wasnt overheating as far as i could tell. the only problem it has had is since its been cold, it would tick for about 6 seconds before pumping pressure up, and when it was hot it idled at about 20psi.
Click to expand...
Your motor sounds better than mine. I've been running mine for a few years now, but I have a spare in the garage. As long as it keeps on keeping on, I'm gonna run it.
I have piston slap, I think I have an iffy wrist pin, but the motor still runs strong and hasn't failed me yet.
The law of Zen says, as long as I have a spare motor in the garage, I will never need one. :laugh3:
 
Jimminyc said:
yea, i think that i might be better off finding a motor. I didnt see any discolorations though. it wasnt overheating as far as i could tell. the only problem it has had is since its been cold, it would tick for about 6 seconds before pumping pressure up, and when it was hot it idled at about 20psi.
Click to expand...

Too bad your so far away...I have a 4.0 out of mine I'm selling because I went with a re-manufactured motor...$50.00 takes the whole thing.
 
jeepdeepfreak said:
Too bad your so far away...I have a 4.0 out of mine I'm selling because I went with a re-manufactured motor...$50.00 takes the whole thing.
Click to expand...

Damn, you're far away from me, too. I could use a few project motors, with all the restomods I've got on deck....

5-90
 
therein lies the problem with national web boards. Too bad shipping is so pricey. Maybe you need to come do some colorado wheeling Jeepdeep!! :)
 
Back in 2001, I spun a bearing out in the middle of BF Nebraska. No 5 was the worst with noticable wear to the journal and a fractured and spun bearing. Various stages of wear to the others including metal fragments inbedded in the bearing material. I slapped in a set of rod bearings in a motel parking lot and continued on to Moab. 20K miles later, another set, along with the mains. Another 25K miles later, another set. Jeep motors are pretty tough. Mine's now at 256K and has less clicking and ticking than my 97. A new crank or shortblock would be the repair of choice, but then I'd have to spend some money.
 
Buff the journals down with fine emery cloth followed by crocus cloth before slapping in new bearings and you might be surprised at how far it'll go.
 
well, heres the update, i found a guy with a 4.0HO. how hard will that be too hook up to my 89 cherokee? is it much different a harness....different computer?
 
jeepdeepfreak said:
Too bad your so far away...I have a 4.0 out of mine I'm selling because I went with a re-manufactured motor...$50.00 takes the whole thing.
Click to expand...
where in ohio? I'll be there this weekend.
 
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