Hi guys! I recently purchased a 1988 MJ after searching craigslist religiously and finally found one local.
I have a 2001 Jeep XJ as my DD so I'm not new to the jeep scene; however I am new to the renix-era. The current specs on the MJ are the AW4 trans, Dana 30 front axle, Chrysler 8.25 rear with SOA Lift, long bed, and the notorious 4.0L...or so I've seen. The PO I purchased it from told me that it leaks oil like a pig, all over the engine by the airbox - including inside of it. Which from doing my own research on is known as oil blow-by. From the writeups I've seen, this is typically caused by the piston rings going bad or the CCV(?) valve hoses in the valve cover getting gummed up with junk. I did a cold compression test; both wet and dry and got the following results.
Cylinder: PSI (Dry) Cylinder: PSI (Wet)
6: 95 6: 130
5: 95 5: 130
4: 110 4: 135
3: 110-105 3: 155
2: 105 2: 120
1: 100 1: 140-150
Any other tips regarding this blow-by? The next thing I am going to check will be the hoses on the valve cover and see if they are gummed up and hopefully clean them. I did peek into the valve cover and it does look a bit gummy inside but I need to remove the valve cover to confirm.
Now onto my next question..
The PO included a 4.0 engine and trans from a 98 Cherokee; and according to him it would be a direct swap if I needed to pull the MJ engine. The spare engine turns over by hand but I don't have a lot of information on it, whether it's good or shot or if it's even a HO, to be honest. Assuming I have to pull my engine...I've read(and please correct me if I'm wrong!) that it's possible to swap a HO engine into a renix era vehicle just by simply swapping certain accessories; for example.."You will be using the intake and exhaust manifolds from your Renix, along with all your sensors and wiring. Since the intake ports of the HO are slightly different, you use the renix gasket, and exhaust ports and identical. You will need to use your Renix distributor as it is different from the HO design. The flywheel or flexplate from the Renix must be used so that your CPS gets the correct signals. The valve cover from the renix allows you to keep your ccv system intact and requires no modifications. The HO block will have a plug in the coolant galley on the driver’s side of the block, closest to the front, which needs to be removed so your Coolant Temp Sensor can be installed in it’s place just as it is on the Renix. It requires a 5/16” square drive or a modified 3/8” drive that has been ground down to fit. Do this before installing the engine. As for the knock sensor, which is located just above the oil pan on the driver’s side of the engine about mid way, all the blocks I’ve seen are threaded for it. If not, I’ve heard they may be drilled but not tapped. Tap the hole if that’s the case." - directly from http://cruiser54.com/?p=100
I know this is a lengthy first post but any and all feedback is much appreciated, thanks in advance :thumbsup:
