What's involved in a lower engine rebuild?

[Jerry Bransford]

My 4.0L might be getting tired after only 164,000 miles. I'm thinking I might be hearing the early indications lower-end probs... like perhaps rod knock but hopefully I'm wrong.

I've never owned a vehicle long enough to ever need an engine overhaul so I don't know anything about it. Can the lower end be rebuilt (rod bearings etc.) without pulling the engine? Any idea what something like that might run here in Socal?

[igofshn]

If you are doing the lower, I would say go ahead and do everything. You will be happier in the long run. To answer your question, you need to pull the engine to do the lower properly. It would be kind of hard if any machining is required.

[Tumbleweed]

Well...yes-many times it can be done without pulling the engine.
However, doing a thorough job should require having the crankshaft pulled-inspected-and probably machined. You can put new bearings on the old crankshaft and it will last for awhile- but there is a good chance the crank needs turned to give a new surface for the bearings to ride on. If-for instance the rear main seal has been leaking for awhile-the new seal is gonna leak again at an earlier time.
Jerry, the biggest question you need to answer is how many miles are you gonna keep this motor? If your answer is 30-40k miles then slap some berings in there and go for it. If your answer is another 150k-then do it right. The condition of the head, block bore, camshaft, and crankshaft will determine what you need to do.
Now you are getting into quite a parts, labor, and machine shop bill.
Quite often, it is much cheaper to get another junkyard motor with low miles; and or a crate rebuilt motor from a reputable source with a warranty. The downtime of the vehicle that way is something to consider. (Much less than waiting for a machine shop to get the job done).
There was a post here in the last week mentioning used motors for $600-1000 I believe. It would be hard to get one rebuilt for less than half of that in my opinion.

[Jerry Bransford]

Originally posted by igofshn
If you are doing the lower, I would say go ahead and do everything. You will be happier in the long run. To answer your question, you need to pull the engine to do the lower properly. It would be kind of hard if any machining is required.

Sounds like good advice, thanks Al. I poured a can of "liquid engine rebuild" into the engine yesterday which seemed to really quiet the engine considerably. I'll hang in there for the time being and just keep an eye on the engine. Thanks again Al.

Edit: Thanks too Tumbleweed. I do plan on keeping this Jeep "forever" so maybe a new crate motor is the way to go. As you say, that would be a time saver. However, I may be jumping the gun as I almost can't believe with only 164K miles on it that it could already have a rod knocking. I've changed the oil and filter on a very regular basis so at least I've done what I was taught to keep an engine running a lot longer than this. Oh well.

[Iceman]

Jerry, preventive maintenance might be the way to go, or just keep up the regular oil changes and wait till it blows. Then get another engine. See also the thread from Robert in which I replied. I don't know if rebuilding the engine is more cost effective in the long run compared to just swapping it out for a new(er) one with low(er) miles

Heck, maybe you can even work out a deal with Robert

[Jerry Bransford]

Originally posted by Iceman
Jerry, preventive maintenance might be the way to go, or just keep up the regular oil changes and wait till it blows. Then get another engine. See also the thread from Robert in which I replied. I don't know if rebuilding the engine is more cost effective in the long run compared to just swapping it out for a new(er) one with low(er) miles

Heck, maybe you can even work out a deal with Robert

My engine already needs (or at least could use) a valve job so I'm now possibly looking at both top-end and bottom-end work. For that reason, a new engine would probably be the way to go. I'm just hoping I'm jumping the gun here. I'll just wait for the other shoe to hit before doing anything else... siince there's not much I can do at this point except wait and see. Thanks!

[Robert J. Yates]

Originally posted by Iceman
Heck, maybe you can even work out a deal with Robert

Nothing wrong with my 4.0 other than I need 50-100 more HP and torque for towing the camper. There's 89K on it right now and it uses no oil. All its seen for the last 65K is synthetic.

[Tim]

Originally posted by Robert J. Yates
Nothing wrong with my 4.0 other than I need 50-100 more HP and torque for towing the camper. There's 89K on it right now and it uses no oil. All its seen for the last 65K is synthetic.

hell, if the inside is as shiny as the outside of his rig jerry, i say go for it. looks like robert takes very good care of his junk! if i was going to buy a engine right now thats exactly where id shop first

[Jeff Weston]

Originally posted by Jerry Bransford
However, I may be jumping the gun as I almost can't believe with only 164K miles on it that it could already have a rod knocking.

Not that it has anything to do with whether or not your engine is going, but the 4.0L in my dad's YJ gave up the ghost after only about 140K or so miles. The tranny didn't quite make it that long.

[Jerry Bransford]

Originally posted by T.Dome
hell, if the inside is as shiny as the outside of his rig jerry, i say go for it. looks like robert takes very good care of his junk!

Yep, that is for sure, I know Robert does. What bugs me is that my engine has been babied with regular oil and filters changes too yet it's still starting to knock (faintly, not loud yet). I think I'll just go new when it's time since if mine was well taken care of, then it could happen to any other engine that was also well taken care of.

I wonder how long that thick Wynn's "Engine Overhaul" stuff I added Friday will keep the knock away and the engine together.

[Tumbleweed]

Jerry, when I was growing up etc-engines had a life of around 100K typically. Some exceptions. Nowdays I don't think that has improved much. At least, I am not convinced yet. I would be very happy to get 145k out of a motor.

[Jerry Bransford]

Looks like I have just re-calibrated my expectations for my engine, I really thought it'd last much longer than what I'm hearing. Heck, I've never owned a vehicle half this long or that I put even close to 164K miles on it before so this is new ground for me.