terrawombat

An unfortunate, but familiar, sight for a lot of MJ owners. Last picture is after I hit it with the wire wheel - also hit a homemade brake line done by the PO. The floor isn't the worst I've seen on an MJ, but I'll definitely need to break out some sheet metal, tin snips, and my welder. Luckily the passenger side is in great shape with only a minimal amount of surface rust. I couldn't believe that even after 2 years of sitting, when I pulled the carpet out of the truck, the floor was STILL moist.

Here are some random pictures of what I'm starting with. I'm waiting on some painting supplies to come in, as well as some warmer weather since my shop isn't heated. I don't mind working out in the cold, but the paint won't cure properly in 20-40 degree temperatures. So until spring decides it wants to pay NJ a visit, I'll be mostly tearing down the truck some more and fixing all of the rust. I'm in the process of removing the carpet and judging by bottom of the seat frame, the floors may be shot. While I wait for some warmer weather, I'll continue to strip paint off the panel and prep them for paint. I also just got a new rear main seal and oil pan gasket, so I can work on that too if I'd like. This is about the only bodywork I'll need to do on the truck (I hope). There are some small dings and dents in this panel and the rocker is starting to rust out in one spot.

ALL modern vehicles use them. Jeep was not the first. They are a nuisance to change, but they usually last about 100,000 miles (give or take 75,000 :D ), so easy access wasn't at the top of the list of priorities when designing where to put it. If not a crank sensor, then a cam sensor - does the same thing, but at half the speed ;) A lot of modern cars put the crank position (or crank angle) sensors on the front of the engine, but a lot of modern engines are overhead cam designs and access to the timing components is meant to be easy. I guess we should be lucky that Jeep didn't put the CPS in the 12 o'clock position!

Wanted to introduce myself and get my MJ project blog going. I currently own two 1988 MJs, but have had four pass through my hands during my lifetime. I've mainly used them as field vehicles on my parents 250-acre produce farm and they've been great - very few problems and parts are abundant and cheap. The truck I'd like to dedicate this thread to is a 1988 MJ SporTruck with a 4.0L Renix, 5-speed manual transmission, and a six foot bed. I parked the truck in my shop roughly two years ago when gas started finding its way in the crankcase. I wound up buying another MJ to replace its use on the farm, but I decided to keep the other as well and I'm glad I did. After two years of sitting, I finally got around to figuring out the gas in oil issue and I think I have resolved it so it's almost time to start thinking of how to modify this truck. Before I even think about a lift or bigger tires, I need to make sure the engine is 100% sound, which I'm starting to believe that it is. It has 106k miles on it, so it has PLENTY of life left. As soon as I can run some more tests and verify the engine health, I will begin on phase 2 of the rehab process - rust-proofing the body and frame. I'm lucky enough that the bed is completely rust free and I intend to keep it that way. I bought half a gallon of an automotive undercoating paint for the bed and cabin and half a gallon of POR-15 for the frame rails and suspension components. Once the truck is rust-proofed, I'll be hitting the outside with a new coat of paint. Phase three of the rehab process will include larger axles, a lift kit, and bigger tires. I intend to read as much information as I can on this subject as I know very little about the ins and outs of a lift kit. This truck will eventually become a daily driver so it'll be important that ride comfort and stability are maintained. I am also not sure of what height kit I want. I've seen many pictures of 6.5" lifts and they look great, but it seems they come at a steep price. I do have deep pockets, but I need to make a spending cap for myself as I don't want to make this endeavor a bottomless money pit. I have to apologize for the only picture I have at the moment - I will get more when I go home tonight after work. I'm currently taking a wire wheel to the frame and underside of the bed to prep it for paint.

Thanks for the reassurance. I'm always a little bit leery of touching "high profile" engine items like the oil pump or bearings if I don't REALLY need to. The pan does need to be dropped though as there is a significant leak coming from the rear - not sure if it's just the gasket or the rear main seal, but I ordered and will replace both. I think once the leak is fixed and I can confirm 100% that I no longer have fuel leaking into the crankcase, I will be confident enough in this truck to start doing some "fun" upgrades ;) I need to check the clearance of my shop entrance door to make sure I don't lift the truck so much I can't get it out! Oh, and while I have your attention, would you happen to know the best place to get random body parts - such at cabin/windshield trim, those little "crows feet" bed spacers, fender flares (and the metal backing brackets), Comanche/Jeep emblems, etc. I realize I can probably pick all of this stuff up at a dealer for a premium, but if there is an online MJ vendor, I would love to support him/her over a dealer any day.

Did a lot of wrenching/testing/diagnosing on the truck this past weekend and I'm happy to report positive results! Disposed of ALL old fuel in the tank and fuel lines and put 5 gallons of fresh stuff in. Also pulled the plugs and used a propane torch to "clean" them up. Reinstalled plugs, cranked it over and it fired right up. Let the engine get to operating temp, revved the engine a bit - small backfire still prevalent, but NOTHING what it was before. Noticed my oil pressure was WAY down and I was getting a consistent oil drip from the back of my pan. The stuff was thin and smelled like gasoline - looks like I'm right back where I started. Drained the "oil" and put some fresh 20w-50 in. Also, on the NAXJ forums, someone suggested that I may have a lower temp thermostat in since I never really got up to the proper operating temperature, so I bought a 195 degree t-stat for good measure. Upon swapping that in, I found out that person was right - someone stuck a 180 degree thermostat in this truck at one point and since the ECU uses the coolant temp sensor as a method of determining injector pulse width, it could have been one reason why the truck seems to always be running rich. Also, while I was wrenching on the engine, I bought a fuel injector reseal kit since I noticed a small drip from one of the injectors and found a tattered o-ring - decided to replace all 12 for peace of mind. So, new oil, thermostat, and injector o-rings - truck fires up immediately and gets up to its PROPER operating temp of 195 degrees. I purposely only put in 4 quarts of oil so that I could more accurately monitor the crankcase fluid level. I'm looking to see if my gas in oil problem is still lingering. So far, the truck has had about an hour of run-time and I'm happy to report that the crankcase oil level has remained unchanged and still smells like OIL! Hooray! I'm still skeptical, so I'll be doing a lot more testing on the engine in the coming days. Also, while I was letting the engine run, I did a check on every sensor and they all check out fine (I used a webpage to verify my results, but I can't seem to find it. I'm at work and its saved on my home comp). Even my O2 sensor is cycling like it should! Only sensor that MAY need to be replaced is the coolant temp sensor - the ohm reading on a warm engine was about 360-375 ohms, which is a little high, but nothing crazy. Also ran a compression check on the engine to put my biggest fears to rest. On a warm engine, no spark plugs in, throttle fully open, I got readings of 140-160 across the board. Seems a little high from the spec I found in the service manual, but I suspect my gauge reads a little high and there is also a good amount of carbon buildup from years of running rich. I still want to do a leakdown test to get an idea of what condition the rings are in. Next up - dropping the pan, replacing the rear main seal and oil pan gasket. Going to clean up as much of the crud as I can that has accumulated on the bottom of the engine from years of neglect. Thinking about replacing the oil pump while I'm in there, but I currently am getting 25psi at warm idle and about 40-45 psi when I rev the engine up a bit so I'm thinking a new oil pump might not be necessary. Anything else I should look at while I'm down there? I've also been prepping the frame rails for a nice, thick coat of POR-15. I'm also going to hit the entire bottom of the bed with an undercoating spray that I just ordered. Also been sanding the rest of the body in preparation for a full repaint. This would have all been done a year ago if the dang engine would have just cooperated. Not really sure if it's fixed yet and if it is, what I did to fix it. I think it heard me say, 'if this damn engine would function properly, I'd go ahead and put a Motion Offroad 6.5" lift kit on this truck.' Since then, it has behaved VERY well.

I have the exact same truck as you, but in black. Thanks for giving me some great ideas for the interior! I will definitely be going with the bucket seats and center console w/cup holder...looks like it was supposed to be that way. Great work!!

1988 Comanche w/4.0L and 5-speed transmission. Truck ran a couple years ago, but kept getting fuel mixed in with the oil. Parked it, bought another MJ and basically forgot about the truck. Just came back to it a couple months ago and had the injectors professionally cleaned - someone told me stuck injectors could be leaking fuel into the engine and past the rings, hence the gas/oil mix in the crankcase. Fast forward to now - replaced the alternator, installed new plugs, truck started and ran, but with a very noticeable hesitation coming off idle and some ferocious backfires as the truck came down from the upper RPM range. Plugs were black as night indicating a rich mixture. Was running open headers so I put the front pipe and cat back on. Tried to start the truck to see if the hesitation ceased, but the truck will not start for me. Pulled plugs and they're soaked in fuel - used a torch and burned them clean again, reinstalled and the truck will maybe start up once, bog a little, and die. Subsequent restarts only end with the truck cranking over endlessly with the occasional "gunshot" backfire - definitely coming from the exhaust. Truck has 38 psi of fuel pressure when cranking - but fuel delivery was never really an issue here, obviously. Grounded a spark plug to the valve cover, cranked, and I've got spark, although it was tough to see how strong it was. Replaced the crank angle sensor with a known good one, swapped the ignition coil from my other MJ, but nothing seems to be doing the trick here. Even went back to open header since the truck ran fine when I had it in that configuration, but nope - still getting fouled plugs and the pleasant aroma of gasoline in my shop. Anything else I'm missing? I suspect the oxygen sensor, but I feel that the truck should at least start up for me, even if the current O2 is bad. I read somewhere that water temp sensor might have a play in all of this? When I go to crank the truck, I notice that the water temp gauge will peg all the way to the right - is this normal or a possible indicator that something is amiss? Help me out here - I want to get this truck running good so that I will have motivation to repaint it and restore it...otherwise I may just scrap it. Thanks.