ParadiseMJ

2 yrs old...and less than 2,000 miles. There was a bit of "sediment" in it when I flushed it. My XJ had the same sediment (and same CSF 2 row radiator) after it's first flush at about 20K miles. That radiator (in the XJ) is still going strong with the same cooling set-up. The internals of the 4.0 in the MJ are cleaner than the XJ.

So, when I took the t-stat out I was cleaning the housing and found a hairline crack at the the top of the bottom bolt hole of the housing. The crack is evident on the outside, it goes all the way across, but the inside of the housing looks fine, no crack. There was no evidence of leakage, but I'm wondering if it possibly let out enough pressure to not let the system to properly pressurize. However I don't see how it could let out pressure without leaking coolant. Anyhoo, I put it all back together and drove home. Still going over the 210 mark but not by very much. Going to replace the housing with a spare...or even a new one just for shlitz (I don't like that crack)

I got a new t-stat. Took the old one out. Tested at work in a pot of water, side by side, with a digital thermocouple type thermometer. They both started opening at 192 and were both fully opened at 201. They both opened at the same rate and both began closing at the same rate when removed from the water. Identical t-stats. So, I'm thinking there is nothing wrong with the old one. Putting the new one in anyway. I'll see what the gauge does on the way home today. Then it's the IR gun to see how accurate the gauge is.

87-90 has a metal heater valve right up at the "pressure" bottle as part of the voodoo plumbing into and out of the bottle and core. 91 - 96 has the funky plastic valve and 97+ no valve...it's just straight through from water pump to core to t-stat. Zak...your was removed and modified at some point.

The screw in connectors need to be straight on. Any little deflection in angle will futz up the threads. A crow foot 18 mm wrench with a long extension is the correct tool to remove and replace them. If you already "bent" it at the crimp at the fitting you'll likely need a new line. They're really surprisingly inexpensive and I've had AutoZone lines on mine for years without any problems. Then make sure you have the correct o-ring. There are two types on XJ/MJ lines, one fits into the groove and one sticks in at the end...one or the other Make sure you make yourself enough room to work...remove the air box if you haven't already.

Well, still struggling with this. So far, with a new cap and flush n'fill I got no results. Same old creep up the hills. When the hills are over and I level out, temp comes right back down. Could someone explain to me how a marginal t-stat could cause this? I know a t-stat only costs $10 but I just wanna understand it. When I start out temp climbs up to just under 210...then, it drops down to ~190 and runs at 70 mph on the flats at 195. So, the t-stat is working (?). Then when I hit the hills, it slowly creeps up to 220-230 and stays there until I get up riding along the relatively flat ridge and into slower traffic in town, up and down small hills. Still, going 45-50 in town or stopped at a light, it's right at 195-200. It's only 82 here today. I don't want to have to throw a bunch of parts/money at this until I KNOW I have to. The new 50/50 mix coolant is sparkly clean flourescent green, ther are no air pockets in the system, the new oil is perfect amber/clear. Oil pressure is 25-30 or so at hot idle (750 RPM) and ~45-55 at 2400 RPM. The tranny temp is not going over 180F on the steepest, slowest part of the hill. Turning the e-fan on does very little to lower the temp (5 degrees or so). I'm not running the A/C. The heater core is clean & clear. My water pump is not weeping, and with the belt off it turns freely without any gravely sounds or side play. The pump was pushing out a good stong squirt/flow yesterday. No other pulleys are dragging. My truck is empty, with a half tank of gas. What I have NOT done yet: Replaced the t-stat ... which I'll probably do when the thing cools off this evening. (Especially if someone can explain why I'd need to) Cruisers exhaust restriction test Shooting an IR gun at the t-stat housing when it's at it's hottest to see if I'm getting a good reading...inside. An actual exhaust gas test in the coolant. Compression test Thanks for any input

A 180 t-stat will not control max temperatures. There is no indication that the head gasket is involved. No exhaust gas bubbles in coolant, no oil/water co-mingling. Were talking 10-20 degrees here. This would be my last resort. It's not overheating in traffic or creeping while idling...it actually cools off when idling. The fan clutch is a ZJ HD fan. The e-fan is a 97 10 curved blade fan. There is lots of air flowing. That part works. ...and BTW it is a cooling issue Anyhoo, I flushed the system yesterday. The coolant wasn't too bad, but there was a bit of sediment. I flushed the heater core separately, and then the whole system altogether. I also removed the pesky heater control valve for better flow. If that doesn't do it, I'll replace the t-stat today. After that I'm considering relocating the tranny cooler away from the grill to eliminate some heat flow there. No air restriction due to crap on outside of radiator, condenser or trans cooler...it's clear there. Thanks fellas.

:rotf: I just had my PITA neighbor spend ten minutes explaing to me how water flows...downhill. That was Saturday, he explained it to me again yesterday. I told him that it's not the only thing that flows downhill *wink, wink* I removed heater valve from my XJ's years ago with absolutely no ill effects (like hot air in summer or making A/C work harder. Keeps heater core nice n' clean. I removed it from my MJ yesterday. Driving to work today I could feel NO warm air coming into cab.

I was very surprised that the rad cap had absolutely no effect. The old one looked quite old even though I know it's only 2 years (and 1500 miles) old. The seal gasket was wavy, and the hold down tabs looked bent. So on to flush etc. today.

Work week plan...I'm DD'ing the MJ this week to sort out my running hot issue. I popped a tranny cooler hose in my other (commuter) car so it sits, while I deal with the Jeep. I've already changed the oil...Rotella 15-40 + MMO. Process of elimination: By today, or tomorrow or the end of the week I should have it zero'd in. Monday: New rad cap...and I bought a new (used from Chevy Astro) overflow tank with new hose. No change Tuesday: Flush n' fill / t-stat / heater core flush / delete heater control valve. Coolant dirty, but not super bad, no oil or scummy scum in it...it had lost it's "green-ness" though Wednesday: Thursday: Friday:

I checked the cat today...the old fashinoned way. Drove around for 20 minutes or so. Cat was hot, but not HOT! No rattling. Also it looked really nice & clean a couple months ago when I replaced the muffler. I'm going to replace the rad cap today and see what happens. Are all the caps made in Mexico/China/India?? The radiator has less than 2,000 miles on it. All metal CSF 2 row, coolant still looks good from rad install. Gotta get a vac gauge too.

A couple weeks ago I finally corrected my speedo gear to adjust for larger tires. According to my GPS and those "speed checkers" on the side of the road the speedometer is spot on. I thought that the speedometer and the odometer both run off the same gear/cable. Maybe it does but if I go by the mile markers on the road AND the GPS my odometer is still off by about 15% Is there something I'm missing. I took a little road trip yesterday and I know for a fact that the route is 121 miles from my house to my destintion. So, round trip odometer should read 242 miles but it only reads 207 miles. Didn't take any side trips, shortcuts or nuthin'...and my wheels were not off the ground for 35 miles.

That's interesting. I did smell some hot metal smell...and it seem to plateau out at around 65-68 mph. It was hard to push it faster than that, which was also unusual. The canoe only weighs 60 lbs and is a bit more aerodynamic than my MJ, I'll check that out tomorrow. Yeah, no can do no cat in CA.

Not really a NEW topic, but since it appeared out of the blue...I'm going to post it up anyway. I took a little road trip today to pick up a canoe. Weather here today mid-80's, 120 mile trip one way, mostly highway. Temp started out at 195F for the first 20 miles, then started creeping up a tad past 210. Turned on the e-fan. Temp went a bit past the 210 mark and stayed there the whole time. I had to go thru some slo n' go traffic which actually cooled it off. Some info about my rig: 88 4.0L AW4 Open cooling converted, couple years ago Coming back, same thing, 195 for 20 miles or so, crept up to 210+, and stayed there. When I started back up the hill...mild grade...about 10 miles, it then went to about 230, with the e-fan on, in third. Never really gotten hot before So I'm thinking a couple things: Rad. cap May need flushing No sign of water pump trouble Ideas??

Uh duh, yeah,. That's what I meant...research, using correct parts, do it once and do it right, but more importantly do it right.

My bad. I did not necessarily infer or substantiate that Ford parts were "ratty". I was just using that reference as an example to the PO that just throwing s**t together because it's cheaper is not going to solve the problems he's experiencing with the front end and the lifting of the truck in general. I see many builds where guys are just using parts that might fit...like those spring spacers...THOSE are ratty. It seems like he was just throwing them on there to boost the already funky springs without making any compensation for the rest of the the "system", and then wondering why it was f**ked up.

Money...although extremely helpful...is not all together the answer to getting decent parts, and putting it together correctly. Being impatient and just slapping random parts on it will just bite you in the arse later, as in, you'll just have to take it apart and fix it right down the road. F-150 sway bars and links....are for f-150's, no matter what "some other guy did". Junkyards, Salvage yards, ebay, craigslist etc. all offer correct parts at seriously less costly than going out to buy the best, most expensive, coolest, shiniest parts. I have built my MJ from almost all "recycled" parts and alot of research and personal work. My MJ is pretty tight and right now. When I got it for $400 it rolled up on a trailer, without wheels, or an interior. It's now a regular driver, on and off road...and a regular chick magnet (down at the senior center) I developed a relationship with my local JY and it has done me good. I'm not a "real" mechanic, it's just a hobby. If you're about to leave for boot camp, put it under cover, up on blocks, and start your build when you do have some money. You could also get some reading in on a Jeep FSM and this site in the meantime to give you some ideas about how to build it right

If you have the MJ bench seat floor brackets...all you need to do is get some pre 95 XJ buckets, remove (drill or grind) the XJ floor brackets from the sliders and they will bolt directly to the MJ floor brackets without any further modification. If they are post 95 XJ seats, you'll need to bolt those up with some flat stock (or angle I suppose). You might ask "don't I need two brackets per side?" The answer is NO...one bracket per side. Turn the seat upside down, you'll see. I've done this twice...the first time it took me about 1.5 hours trying to figure it out...the second time it took me 30 minutes from old seat out to new seat in. Piece of cake. However, do NOT use the curved bottom rocker (rocket) slider seats unless you are under 5' 6" as they sit a good three inches higher than regular seats when installed in the MJ.

...Amen. ...and never work around the catalytic converter after a couple cocktails...when it's hot...and you're in a hurry...

Yes...the coolant temp is higher at the head, and so the fan is designed to come on when the relative temp is ~20-25 cooler than what the GUAGE reads (remember, on the RENIX system they are 2 separate switches/sensors). If you ohm it out at the two the stock bung switch goes to 0.0 at 200. But if there IS no lower bung...the problem is finding a suitable switch...you know, since there isn't a bung...which started the whole discussion. Even with a manual switch, or a regular switch, or an adjustable switch, or an alternately engineered switch...your fan will still work with the A/C - Defrost selection on the HVAC controls. This sounds like a good option and you know, since it's adjustable, you can dial it in. Other than a manual switch that is always available. The REAL question is "Which Switch is Which"?? It's a Bi#ch!! :???: Another cerveza please.

A good MANUAL switch will run you $10...just sayin'...and a Gingko pill for the memory!!

Look for a GM switch. I've heard of folks who said the switch off a 90's vintage Corvette (think 327) would screw into the Jeep t-stat...but I can't confirm that. If your dead set against a manual switch it's time to think outside the box.

That is an odd looking MJ.

How's your catalytic converter? Don't know the history...although reading your posts sounds like you've covered all your bases. Could have busted loose with some honeycomb...rattling? cat extra hot? TV cable adjusted? Just a shot in the dark.

The circuit runs through the relay on the drivers side fender just behind the ballast resistor (Renix). Same relay operates the fan when the A/C is on. If you already have the fan/temp switch connector you don't need to do a thing except plug it in (after you've made a space for the switch...ala new bung) IF you ever want to put a fan switch inside, the wire on the relay to tap/splice is the orange or yellow wire (it won't have both). That will power your relay and turn on the fan.