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Rear Main Bearing Scoring - 4.0 Engine Advice?

3K views 9 replies 4 participants last post by  Harper 
#1 ·
I'm new, so I'll do my best to include ALL of the information. Let me start by saying – I am not mechanically inclined at all – no experience, tools or place to work even if I was...

99 TJ (just over 135K miles), 4.0 Manual, 4 inch lift - Third Owner, owned her almost 6 years now... She is my DD (mostly highway and very mild trails).

When I bought her she had a frankenlift (mostly procrap) and when I made the mistake of putting on RC lower fixed arms to replace the worn out stock CA’s, I started getting vibes when I accelerated on the highway. After doing research I learned that I needed a SYE and CV DS to set my suspension up “right.” My girl ended up purchasing a new car and so I got her old car for a short period of time – this gave me a limited amount of time to get my Jeep fixed up right for the next 100K. That’s when it all began…

After $5K later (parts + labor), I now have a new front axle (new front U Joints), all Currie Adjustable CA’s, Megashort SYE, Adams CV DS, Crown HD steering upgrade, all to upgrade to my suspension AND I had to fix a rear main seal oil leak, leaky radiator replaced, oil pump, water pump, rear brakes and a bunch of other things - I’m really hoping I don’t get any more calls from the shop that is working on my Jeep, before I get to pick her up tomorrow.

Full disclosure: Part of the reason the overall cost is so high is because in the beginning I went to a shop that doesn’t know what they are doing as far as suspension modification - if I had gone to the 4x4 shop that has my Jeep now I’m sure I would have saved money in the long run.

Now for the question:

While the shop that is replacing my rear main oil seal was in the engine, they noticed scoring… they believe that the main bearing as a result is starting to go bad. I currently do not have any knocking or oil pressure issues. Again, my goal is to have my TJ last another 100K+ if possible.

Should I consider having my engine looked/worked on by an engine/machine-shop (which is costly) now before I get to the point of having oil pressure/knocking?

Will it be cheaper (labor/parts) to get engine work done now – while I have a car at my disposal (jeep is normally my DD) - or is doing anything that major to the engine a full rebuild anyways and I should just wait and see?

What are your opinions of the scoring in the rear main (per photo below) – do you see it likely that this engine will be able to last another 100K+ taking this into consideration?

Can anyone recommend a good machine/engine shop here in Maryland?

Thanks!
 

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#2 ·
Looks like normal wear for a motor with 100,000 + miles

I had my pan off at 86,000 and they looked similar, I used the analogy, "Since I am Here" and I replaced all my bearings after I used "Plasti Gauge" to check my clearances. Napa does have .001 oversized rod bearings available, and if you do all that, it's not a bad time to change the oil pump.

You only want 100,000 more miles, I did better than 230,000 more after servicing.
 
#3 ·
@crallscars - Thanks for your response. I would love to drive my TJ for at least another 100K more, ideally it will go past 350K in the end. My friend had a Wrangler that went 350K and continued to run for another 5 years after the odometer failed - no serious engine work was ever done/needed.

I am not doing any of the work myself because I don't have the skills, experience, tools or space to do it. Right now my main rear seal is being replaced at a 4x4 shop, but they do not do engine work beyond replacing the seals...

With that said -
1. Would you advise me to pay a machine/engine shop to replace all of my bearings?

2. Since it's "normal wear" should I just assume my 4.0 will last at least another 100K+ miles without any serious engine work?

3. If this were to turn worse in the next 60K and become a knocking or oil-pressure issue, would it cost more to have the engine repaired then vs. doing it now?

4. Do you believe it will be possible to pay a shop to replace my bearings without doing a full rebuild, which from what I understand can be very expensive? - if so any idea what that should cost?

- Oil Pump, main seal, water pump, thermostat and radiator are being replaced by the shop right now... Thanks!
 
#5 ·
honestly if it was me id just run with it and let it ride since you cant do the work yourself. those dont look terrible and if you havent had any issues id say its fine to continue to run them. but then again you could ask your current shop how much to replace all the bearings.

thing is once you get into the bearings what else could be needed? is your crankshaft damaged? this could turn into a can of worms real quick in the long run your probably better off putting a motor into it
 
#6 ·
Thanks for your input.

The shop that has my jeep now can't/won't do that kind of engine work. They did say the crank "appeared to be okay" - but like you said, once you get into it, it can turn into a full rebuild.

I just wish I knew all of this from the get go, before I purchased a full set of curries, SYE, CV DS and other upgrades because you never get money back for that stuff when you sell, and I'm starting to think that this TJ won't be the kind of jeep that can go the distance...

Maybe I can try to trade it in with some cash for a JK with low miles, FML...
 
#7 ·
If your oil pressure has been good, and you have no bearing noise, I would put it back together and keep driving it. It really won't make much difference if you have it done now or when they get bad 60 or 70k miles down the road. It just means that you've milked that much more life out of your engine by waiting.

Kind of like buying tires before you really need to...you wouldn't be getting as much value out of your $'s.
 
#8 ·
Thanks Water Dog - that was one of the biggest concerns/question I had, will it get worse by driving it in terms of engine-repair/rebuild costs...

I guess it's unlikely that it will go another 100k+ without work right?
 
#9 ·
It could go another 100k...who really knows? The point I'm making is that it really looks from the picture like normal wear, so why change it, if it's not used up? It won't hurt anything else to keep running it, and if it eventually comes to an engine rebuild, the parts won't change because you keep running it (within reason).

Just make sure you keep the oil/filter changes up on it.
 
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