Short Story

WILL JUST SWAPPING BEARING LAST? or is it doomed to eat up the new bearings without the crank cut down and if so any idea how quickly?

Long Story

My daughters 2000 XJ trail rig with a 99 JY motor lost oil pressure a few months ago, Since it was rev'd to 5000 rpm's in the mud many times and had no knocks I though for sure a bad oil pressure sending unit. 1st outing it dropped to 3-5lbs at idle and no more than 30lbs driving down the road (all when hot - cold it was 40-50lbs), by the 4th outing (usually once a month) it dropped to 0 at idle and 20lbs going down the road and I thought time to get a manual gauge on it and see what is up. YIKES



I think normally it is cam bearings for poor oil pressure but it needs a new rear main seal, so I decide I am going to start on the bottom end, check crank and rod bearings, and put a new oil pump (decided on a Melling Std Pump - everyone said High Volume would starve the pan when off camber)

So yesterday I pulled a Main and a Rod Bearing (no sludge in pan) and they looked like this - YIKES to the rod bearing.




Main Bearing to the Left, and the FUBAR Rod Bearing to the right.



Rod Bearing Cap on top, and Rod Bearing cap side on the bottom.

This is my daughters rig, she just graduated college and really not in the budget to do a complete motor tear down, so either its another Junkyard motor (about $150 at half off days at our local PicknPull), or I swap in bearings, oil pump, and a timing chain (its stretched)

• I got the Melling Oil pump and pickup for $75 total from PepBoys
• I found Clevite Bearings, Rod, Main, & Cam for $80 for the whole set.
• I found a Cloye Timing Chain kit for $35
• I have a Felpro oil pan gasket set in stock.
• I found a Felpro Head Gasket and bolts if needed ($65-105) - may try to leave intake and exhaust on if possible since after market header was a pain to get bottom 2 center bolts tightened.

Any Thoughts or Suggestions ????

Thanks

 

I have personally tried to swap the bearings a couple of times and never had any luck. It doesn't last! I would say get a crank kit and machine the rods back to standard install a new pump and that will last. But when your that far it's not much more to bore and do new pistons and rings.

 

PS: Crank Pictures




Rod part of Crank



Bearing Main part of Crank, 2nd one from front of motor.

 

Do you generally get 500 miles out of it, or 10K miles? or ????

If I can kick this can down the road a couple of years (10K miles) it will be better all the way around.

If I am pulling the motor, then I am going to swap hers with the motor out of my 98 that is a garage project, then taking her motor and building a stroker motor, but I am tired of my jeep being a garage project and really don't want to add to its "To Do List"

Plus here in Florida wheeling requires a lot of water crossings, I see a lot of hydrolock motors, I really don't want to dump a lot of money in a motor that I may blow up the next time out..... Yes I have a snorkel, but I have seen them fail too.

 

I did one that lasted 3 days of normal driving, no wheeling. I did another one that lasted a few months of weekend wheeling, and no highway driving, trailer queen.

About 3 years ago I did a friends. I put a crank kit in machined the rods back to stock and all new bearings and pump. He was tight on money so I honed the cylinders and put on new rings and a used performance cam with new bearings and it still runs really really good.

 

Hmmmm, $80 for Clevite Cam/Rod/Main bearing kit, or rebuilt Crankshaft w/Rod & Main bearings for $148 after discounts (Cam bearings if I need them later run $35) - so roughly $100 more for a crank, but generic bearings I am guessing.

https://shop.advanceautoparts.com/p/...420/15950234-P

 

Well now a buddy is saying a Crankshaft should not be my worry, but oval'd out Rods are?

For such a strong motor (the Jeep 4.0) it sure does not appear to be open to quick fixes.... LOL

 

Hmmmm - the local PnP just received a bunch of 96-99 Cherokee's and its $160 for long block $180 with accessories plus tax (about $250 OTD if I keep the core) - I am struggling which direction to go... PS: The above motor is a PnP motor we got about 5000 miles out of, but generally I have had good luck with them. Then again a Chevy LS would cost the same from PnP and would look great in my other Jeep (a long term garage project jeep) - what is another couple of $1000 to get it bolted in... just a few more years of being a garage project.

 

Your friend is correct, but the crank also looses its shape a tiny bit and will spin the new bearings. That is why I said do a crank kit and recondition the rods.
But I vote LS swap!!!
The quickest and easiest way would be to get a junkyard engine, and hope it works! Lol.

 

Id also say the cam bearings are also adding to the loss of pressure. As the current engine didnt blow up its a great canadate for a rebuild. A pick and pull motor is the quickest or by a running junk. Any XJ 91 or newer or a ZJ works with your electronics and accessories.
Recently on Craigslist was a very rust ZJ with 46K on the clock. Still kicking my self for not trying to get it.
Ive done bearing changes with good luck never loosing one. 10+
Good luck with her Jeep

Ron

 

@bryweb I know it's been a few years 😂 but what did you end up doing? I'm in the same boat!

 

Welcome to CF.

GOOD chance he's not going to reply. Might want to start your own thread.

 

I put new rod bearings, new oil pump, new timing chain, new harmonic balancer and crank seals and put it all back together, had the same problem, got disgusted, picked up a parts Jeep with a good motor and swapped it in, the bad engine is sitting in the garage waiting to make a Stoker Motor out of it.

Best I can figure the Cam Bearings are trashed, they are one of the last items to get oil before it returns to the pan.

 

Actually the lifter gallery gets oil directly from the pump and everything feeds off of that. Most of the oil flow will exit at the biggest leak, which in this case was the rod bearings. Pressure then drops everywhere else in the system.

Since the LS was brought up, it's a great motor, but for an offroad rig, why not use an old smallblock. They are cheap and there's tons of them around. The only problem I can see is using a carburator on a rig that might flip over. As far as oil starvation is concerned, about the only way to prevent that is to dry sump it.

 

The main goal of a snorkel is to draw cooler air in than is right in front of the vehicle.
As a water crossing add on; ymmv.