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I'm looking for opinion and ideas on what do do. I have an 88 mj pioneer that I have done a lot of upgrades and put a lot of time and money into it for the last 5 years. The mj is not a daily driver as I own 2 more jeeps. The mj is primarly used for dump runs, to carry stuff for the house and yard and in the winter I plow my own driveway. The mj has the 4.0 engine, peugot tranny (in very decent shape as of this writting) and a swapped mj d44 / non disco 30 turning 3.55 gears (from an auto) which works very well with the 30 inch tires I'm running.

 

Now my dilema is that the engine has 165 K and its starting to burn oil. It has the dreaded blow by that I have been trying to eliminate or reduce with little sucess by trying just about everithing we talk about here on the board. The mj runs fine and strong but I know shes starting to burn oil. I'm starting to look for engine rebuild or swap but to swap a 20+ engine from the junk yard is going to be hard to find one in good condition so I'm thinking in a newer 4.0 using the renix fuel injection. Has anyone done this that can give me a few ideas or what to look for ??? What year engine is the easier one to swap? 91-95 years or 97 to 2006? thanks and any comments will be appreciated.

 

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Only 165,000 miles? My '88 XJ has 287,000 miles on it and still runs strong. You don't need an engine. You need to get to a NAPA and buy replacement CCV lines/hoses, then remove the valve cover and clean out the baffles where the front and rear CCV lines go into the top of the valve cover.

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I think you meant to say swapping in an HO engine, instead of a renix... you currently have a renix system, and the 91 newer system is the Chrysler HO system. To swap in an HO, youll need the entire engine harness, dash harness, HVAC system....best to have a complete donor sitting next to your truck if youll be doing this. But I agree. Your truck isnt ready for a rebuild yet. In addition to the CCV system upgrades or repairs, you might also look at getting new valve stem seals installed. They could be dried up and allowing oil to be sucked into the combustion chamber. If it still runs strong, and doesnt knock, then everything else is fixable!

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Only 165,000 miles? My '88 XJ has 287,000 miles on it and still runs strong. You don't need an engine. You need to get to a NAPA and buy replacement CCV lines/hoses, then remove the valve cover and clean out the baffles where the front and rear CCV lines go into the top of the valve cover.

 

The previous owner did not maintaned the mj too well - I bought it because it virtually has no rust becausw of years of neglet and oil leaks from just about everywhere. The undercarrige had a nice oily undercotting. I have removed the valve cover several times to clean it including the towers, all the vaccum hoses had been cleaned and are clear of gunk as well

 

Dump runs, lumber yard runs, and plowing the drive way? I keep running it until it dies and then find an identical engine in good shape used. The 4.0 is a great engine and not a tough swap but it is a lot of work.
,

 

I know, I know but when I take the truck for a trip to get something, the smoke at the rear is visible and it just does not look good, and I know is not going to get better....

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I think you meant to say swapping in an HO engine, instead of a renix... you currently have a renix system, and the 91 newer system is the Chrysler HO system. To swap in an HO, youll need the entire engine harness, dash harness, HVAC system....best to have a complete donor sitting next to your truck if youll be doing this. But I agree. Your truck isnt ready for a rebuild yet. In addition to the CCV system upgrades or repairs, you might also look at getting new valve stem seals installed. They could be dried up and allowing oil to be sucked into the combustion chamber. If it still runs strong, and doesnt knock, then everything else is fixable!

 

I'm aware that I have a renix system, what I ment was to swap an 4.0 HO but using the renix fuel injection since a complete HO swap requires so much more. The jeep runs strong and does not knock - I'm going to look into the valve stems seals....thanks.

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I put in a 4.0 from a 92 cherokee before I knew there was a difference. Since I only got the block and heads, it still is a RENIX system and works fine after install.

 

Ive run into similar situations to this at the dealership in the last two years. The first was a Liberty that had a used engine put into it at another shop, and for the life of them, they couldnt get it running. We swapped cam and crank sensors, and tested the circuits... all was good, then we decided to investigate what years were compatible with the body's computer system. Turns out it had the wrong year motor in it, and the tone ring for the crank sensor was different... bad thing was, the tone ring is part of the crankshaft! Stupid people don't do their homework! Another one was a Sebring Conv.... same situation.... motor swapped... won't run. I unplugged the cam sensor and the engine fired right up.... tested the circuit, swapped the sensor... no fix. Investigated again... wrong year engine....incompatible computer system...except this one the only difference was the cam tone ring.... they paid the 10.4 hours we charged them for diagnostics and labor to replace the entire timing chain and all gears and water pump to get this thing going.

 

Morale is .... be careful what motor you get and do your homework!

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But for the 4.0L the "tone ring" for the CPS is the flywheel or flex plate. If he keeps the Renix system, all he has to do is keep the original flywheel or flexplate and CPS.

 

The ports on the HO head are shaped differently and set slightly higher, so making the head match up with the Renix manifolds offers some challenges. Not having done the swap I don't know what the best solution is. The throttle bodies have different bolt patterns, but the "easy" way just might be to drill the HO intake manifold to accept the Renix throttle body. You might also try a search -- I think someone reported that you can adapt the HO throttle body to use the Renix sensors. (???)

 

Like the man said ... do your homework. But this swap has been done numerous times. It can be done, and it ain't rocket science.

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:agree:

 

165k is still fresh for these motors. Mine has 104k and was neglected (thick sludge under the valve cover). But after some cleaning and fixing from advice on these forums, she runs great.

 

Before you decide to swap the engine. Try swapping in a '97+ XJ steel valve cover. You'll need the specific gasket and bolt gromments for it. Cured my "blow by" issues. HTH

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i think i have the answers you're looking for...

 

the PO of my truck swapped in a 97 motor (not knowing that the intake/exhaust was different) and it ran just fine.

 

however when i found out it was wrong i began swapping things around and fixing it up correctly.

 

in order to put a late-model 4.0L in your truck while retaining the renix fuel injection you will need a BUNCH of stuff

-HO fuel lines (can be spliced with your own underneath the truck)

-HO intake (preferably 99-01 just because)

-HO fuel rail (i used a 91-95 one don't know if it matters)

-HO exhaust manifold and intermediate pipe

-and either adapt your throttle body to the ho intake with a magic spacer or adapt your TPS to the HO throttle body

-swap over a bunch of sensors, figure out how to keep the wiring for the ECT and Knock sensor off the exhaust

-late-model power steering pump/lines/brackets. (IIRC you use the renix return line and cut it to fit, and the HO pressure line)

-figure out or ask me when the time comes and i'll figure out which belt length i used (no belt for a cherokee will fit, available commonly at any parts store, just not for a cherokee, ordered by length)

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I can confirm that the renix intake manifold will bolt right up to the HO head and the engine will run (everyday :D ) No the ports don't line up just right, but it does run and there's no fabrication required.

Obviously this is a less-than ideal setup, but if you're not up to the fabrication of adapting the renix tb to the HO intake, or the wiring headaches of swapping both the dash harness and the engine bay harness, then this would be my suggestion.

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I can confirm that the renix intake manifold will bolt right up to the HO head and the engine will run (everyday :D ) No the ports don't line up just right, but it does run and there's no fabrication required.

Obviously this is a less-than ideal setup, but if you're not up to the fabrication of adapting the renix tb to the HO intake, or the wiring headaches of swapping both the dash harness and the engine bay harness, then this would be my suggestion.

no wiring swap required if you leave the renix injection so problem solved there,

and 100 bucks at HESCO will buy you a TPS adapter and then you're fixed up. (and you can get a bored throttle body like everyone else)

 

it will bolt up, it does run, it doesn't get bad fuel mileage, it even passed emissions on my truck. but that DIDN'T MAKE IT RIGHT.

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I'd be more shocked if it didn't leak/burn/blow some oil. It's a Jeep. They do that. Don't fret too much over it. that coating of oil underneath is the Jeep's version of rust-proofing. :D Does it still make good power? does it blow clouds of smoke out the tailpipe?

 

Start with fixing the blowby (doing the stuff Eagle mentioned). That might actually cure your ills (the valve cover gasket is a known leak problem). Then work on some of the remaining seal leaks. Unless the block literally blows up or knocks horribly, there's hardly any reason to undertake an complete engine swap. :thumbsup: It just needs some maintenance done, that's all.

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