Brandon Adams

i know the question has been posted countless times because ive read countless posts but this is really more of a request for advice on what to do if you were in the situation. here goes:

recently bought an 01 cherokee. 158k. was unaware of the 331 head issue at the time.

cue unexplained loss of coolant and low oil pressure when hot. (low enough that the gauge actually stops reading anything when stopped.) when rpms are up oil pressure is anywhere from 28-35 hot depending on rpms/load etc. i know oil pressure normally drops as it warms up and the minimum for the 4.0 is 13psi hot idle. im between 4-6 when hot verified with mechanical gauge.

back to unexplained coolant loss:

ive checked for leaks. cant find any. pressure tested twice for an extended period and pressure did drop to the point where any external leak should have been evident. cap did not hold pressure well, but if cap was bad coolant would just be forced back into reservoir providing there is no evidence of an external leak at cap which there is not.

there is some peanut butter on the cap, and the interior surface of the valve cover seems to have a light coating as well, more than just typical condensation, however none on the dipstick.

engine does idle rough at times, especially when hot, almost always after driving for awhile then stopping somewhere for a short time then driving again similar to the heat soak issue.

now as far as the coolant leak my assumption is that the head is indeed cracked, but the majority of the coolant might be making its way into cylinder 3 or 4 or possibly both (which could explain the rough idle/occasional misfire codes that resolve themselves over time) and being burned off even though exhaust doesnt smell sweet. ive put over a gallon of coolant in it in the +- 2 months ive owned it and the oil level has not increased, its actually decreased a little bit so i dont think the majority of it is ending up there.

so i do know at least the head needs replaced and i am ok with that. however i am stuck between a rock and a hard place because i dont have much money to be dumping into it.

i dont have enough for a reman engine

if i bought a used one i have no guarantee it wont have the same problem this one does because of the changes that were made in head design and block casting/ignition system, getting an older or newer head would be way more money/work than i can pull off right now.

my other option is pulling the pan and pump and checking that out and possibly replacing it or cleaning the pickup screen/tube and pressure relief valve.

but if its the bearings im kinda back to the used engine which leaves me with no guarantee i wont be doing this whole thing again at some point.

if its the bearings, after its all said and done the cost or replacing cam bearing which requires a special tool to remove/install from what ive read+crank bearings, seals, gaskets, fluids, etc would be similar cost to buying a reman engine so thats not really a possibility.

my last option is to cut my losses and get rid of it, which i really would hate to do because its a solid vehicle aside from this. no leaks, minimal rust, good tires/brakes and almost all suspension components have alreay been replaced.

what would you do, and how would you go about it?

Bocefus

That engine is done. No use pulling the pan or changing heads at this point. If you don't want to scrap it, put a used pre 2000 engine in it. You will have to fabricate new mounts for your coil pack and install a new aftermarket exhaust manifold, but not a big deal. Just search this forum for info. I wouldn't go with a used 2000 and 2001 since like you mentioned, you could be running into the same problem.

Open the oil fill cap and shine a bright flashlight down it. You will probably see a visible crack in your head.

moparado

I agree with Bocefus, that engine is in all probability toast.
If you plan on keeping the Jeep for years to come, i'd invest in a re-man'd short block and order a clearwater head if you can afford it.
Thats what i'm gonna do if my 00 head cracks down the road. So far so good though with my Chrysler replacement engine.
Getting a good reliable used engine IMO is a toss of the dice especially an 00/01 engine.

Brandon Adams

if i were to put a pre 2000 in it would i need to swap out pcm and wiring harness since the ignition system would be different, or would the connectors still be included for distributor etc.

nujeepguy

where would you get the short block??

Bocefus

You would not need to swap out the pcm and wiring harness. You would just re-use the factory 01 connectors and distributor. As long as you use a 96-99 4.0 donor, the only thing you need to do is mount some brackets up to the valve cover to hold the 01 coil pack in place, since the head on a pre 2000 4.0 is not threaded to accept a coil pack. That along with an aftermarket header, and you are set.

See this thread for details:

https://www.cherokeeforum.com/f2/200...t-fits-124299/