Best guide for 4.0 repair / rebuild?

EJD

EJD

TJ Overlander
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Oh where do I begin...

On a recent excursion I apparently threw a rod on the bottom end and have a significant knocking sound with the engine running. I do not know how bad the damage is yet, only that there is no visible damage and that this knocking started while simply driving down the highway only 5 or so miles after stopping for gas. So I hadn't been driving long once whatever happened happened.

My plan is to remove the engine, assess things more, repair what needs repairing, put it back together and continue on. I have a brother willing to lend a hand who has done this exact thing before with his TJ before, and we have some items from friends that are willing to loan us a cherry picker and a nice garage heater since winter is here to stay.

I guess what i'm wondering is can anyone recommend any literature or guide books? or know of any other good things to replace while I have the engine out? This totally sucks and am super bummed out about this, but at the same time, i'm hoping to use this as a learning experience and gain a better understanding of my TJ in the end. That and hopefully not have to replace my entire engine...
 
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Sorry to hear the news. How many miles do you have on it? I googled jeep 4.0 rebuild and tons of info came up including videos. Looks like your going to have an over information issue.

Good issue to have I suppose
 
Jerry Bransford said:
Get a .pdf copy of the Mopar Factory Service manual for your model year, it'll provide everything you need in complete detail. The FSM is available to be downloaded for free from here at https://wranglertjforum.com/threads...ice-manuals-fsm-technical-documentation.4618/
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Oh great, I actually have downloaded it before but didn't realize it had details on rebuilding/repairing the engine. Does it include all the torque specs and everything too? I haven't had time to fully check it out yet.

Alex01 said:
Sorry to hear the news. How many miles do you have on it? I googled jeep 4.0 rebuild and tons of info came up including videos. Looks like your going to have an over information issue.

Good issue to have I suppose
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Yeah i'm pretty bummed that this happened but like I said, i'm trying to take it as a learning experience and just hope we are able to find out exactly what broke in there. My TJ has 166k on the clock right now, which I know isn't as high as one would expect to be having engine troubles.
 
Why not spend 2k on a remanufactured crate engine? Did that on my old XJ, bolted it in, and it even came with a 30k mile warranty. Ran like a brand new 4.0!
 
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Chris said:
Why not spend 2k on a remanufactured crate engine? Did that on my old XJ, bolted it in, and it even came with a 30k mile warranty. Ran like a brand new 4.0!
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Absolutely an option that is on the table...just don't have that kind of money to casually toss around at the moment. I saw @billiebob had good luck with his as well. Plus my brother seems to think we can tackle this fix together for not too much...depending on what the damage really looks like. I'll be sure to post up some pics here for anyone who wants to follow.

I was just trying to get the best info on the topic for the job ahead. Obviously this forum is at my disposal to some degree for those willing to help out along the way...and I greatly appreciate it!
 
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EJD said:
Absolutely an option that is on the table...just don't have that kind of money to casually toss around at the moment. I saw @billiebob had good luck with his as well. Plus my brother seems to think we can tackle this fix together for not too much...depending on what the damage really looks like. I'll be sure to post up some pics here for anyone who wants to follow.

I was just trying to get the best info on the topic for the job ahead. Obviously this forum is at my disposal to some degree for those willing to help out along the way...and I greatly appreciate it!
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I'm curious to see what the damage is. If it's minimal, then yeah, it would be cheaper to just rebuild it yourself. I'm surprised it even happened to begin with given how tough these engines are.

Anyways, I'll be looking forward to seeing photos. Hopefully it's minimal and you can do it while keeping the cost low.
 
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Sounds like you just spun a bearing, if you had broke a connecting rod it wouldn’t just be knocking, you could just pull the oil pan to diagnose it, start looking for a used crank shaft you can get turned down and put in oversized crank bearings for a cheap fix, or go ahead and do the top and bottom end for a fresh new power plant. If it was a broken rod you would have some piston and valve train issues as well.
 
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matkal said:
This thread came up for me in a search. I'm in the same boat, what did you end up doing?
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Hey!,

Yeah so as an update to "this" thread, the issue looks to have started with a severely clogged oil pump pickup (sludge+metal shavings) which caused very low oil pressure, enough to spin a bearing. When we broke the engine apart there was a lot of damage, it was not good. We could not find any parts to simply swap in for the cheaper replacement, the engine was further gone than that. Most likely from a life of poor maintenance from the PO.

I ended up ordering a remanufactured Long Block AMC 4.0L from S&J Engines in Spokane, WA. Then my brother and I pulled the engine out of my TJ, got the new engine a day after I ordered it, literally. They took the core back in the same crate and refunded me $400. Then I swapped over everything else to the new engine, installed a new Melling oil pump and pickup, connected everything back up all with hand tools and the Jeep just sitting on its own tires. It was awesome!

Everything we took off the Jeep we took pictures of, and bagged/labeled it and put in in a bin. So when we put it all back together we did not have any additional parts left over and it all worked out great. There's a few pics of it in my build thread too if interested.
 
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