getandistr

So I've been working on this jeep for a while and finally got it on the road this passed November. Since then it has been running great. It has a snorkel and a hood cowl for extra cooling but otherwise everything else is stock. It was well maintained before I got it and the engine was rebuild 60k miles ago (currently sitting at 168k). Up until 2 weeks ago it typically ran around 190 once it warmed up. The last two weeks with outdoor temps ranging from 32-70 it has warmed up to 210 when idling and 220-240 when driving at highway speeds. Mechanical fan and electric fan both kick on and run no problem. The coolant seems fine but I am planning on changing it soon anyway. I don't see any fluids leaking and I've kept up with the oil when needed. Some additional info: it is sitting on 33s with a 6" lift with stock gearing and is manual transmission. What could be causing this sudden change in run temp?

Cheddarnut

I would look at the obvious stuff. Water pump, thermostat and check the radiator for rust or sludge. Pop the cap and have a look. The radiator is a pretty easy swap and cheap enough if that's the problem. If you did all three that's the trifecta for jeeps and pretty much solves most issues.

getandistr

So I figured out that my fan clutch is shot and hoping this is the reason for the heat. I got the 4 nuts off but I can't pull the thing out. What am I doing wrong?

Eisenschwein

Whatever you do, don't go crazy trying to yank or pry it off... you will smash it into the radiator and have a more expensive problem on your hands. I would start by slipping something thick between that fan and the radiator.

It's probably just stuck a little. AFTER you shield the radiator, I would put something on the fan shaft (pipe or bar or something you can tap with a hammer) and gently tap it a few times to loosen it up. You shouldn't have to beat the crap out of it. But I have seen guys get irritated, start pounding, slip and mash the radiator... 28 grams of prevention...

getandistr

Ok just wanted to make sure I wasn't missing something and that something else needed to be unscrewed first. I will try again.

freegdr

Screw a couple ofthe nuts back on a few threads then yank it off. Nuts will stop fan from gouging rad. After its loose remove the nuts then fan.

getandistr

ok, so here is where I am right now. I did a lot of work on the jeep this past weekend. Put in new serp belt (gatorback), new water pump (hesco hi flow), new t-stat (Stant 195F), new t-stat housing, new fan clutch (GMB 920-2380), new fuel filter, new temperature sending unit (OEM), new temperature sensor (OEM), new Air Charge Temperature Sensor (OEM), new MAP sensor (OEM), new crankshaft position sensor (OEM), new idle pulley (mine was squeaking), used electric fan (mine worked but was squeaking). The finally I did an oil change (10w30 full synthetic) and a coolant flush and refill (Prestone Extended Life 50/50).

Still to be done: new throttle position sensor (OEM), new 2.5" muffler and exhaust pipe (Dynomax), 2.25" CAT converter (Magnaflow), 2.25" front pipe (Walker), new O2 sensor (OEM).

After the work I did do the jeep ran like it was brand new and Monday morning going to work it stayed right at 195F the whole time no matter what speed I was going (it was in the upper 40's and my commute is about 1hr total). Then on the way home it started the same thing again where the temp just climbed like crazy and was right at the edge of going into the red, end even going into the red for a minute at one point (it was 84 outside). I pulled over half way home and made sure everything was running fine under the hood which it was, coolant level was just below full in the canister and electric and mechanical fans were both spinning good. I let it cool down a little then drove the rest of the way home but it stayed above 210 the whole time, hovering just over on local roads and getting close to the red on the highway.

My radiator is the only thing that wasn't changed but that is because it is in excellent condition, I looked through all the openings and found no rust or crud, the old coolant came out completely clean and the flush did produce any crud either.

One additional thing that may or may not be relevent. My oil pressure has been very high the last few months (long before this over heating issue started). Once warmed up it runs between 60-75 psi and idles between 40-60 psi (only at 40 when the engine temp is close to red). I am trying to figure out what the cause of that is but no luck so far. I am thinking I may need to replace the oil pump. I am assuming the high oil pressure is also causing some leaks because I am getting some oil above the drain plug and on the bell housing. Also when changing out the belt I removed the air box (first time opening it in 10k miles) and there was about an inch of oil sitting in there. I am assuming I either have a clog in the CCV line or this might also be caused by the high oil pressure. If anyone can chime in on any of my oil problems as well that would be great.

Finally, even though the temp goes that high the engine does not run rough or any different at all but I don't want to chance it. What else is there that I could be missing to help fix this over heating issue?

getandistr

Please anyone. I have to drive this to work every day and can't afford to have something major happen so I need to fix this as soon as possible.

RTorrez1

One thing you need to do is verify your oil pressure with a mechanical pressure gauge. Connect it the port that the sending unit screws into. Also, verify the temp with an I.R. temp gun pointed at the T-Stat housing. You never know if you are getting true readings unless you verify. Start with that and let us know what you find and we can go from there.

getandistr

Mechanical oil gauge is on order and I'll try to borrow an IR sensor to test the engine temp.

I did one new experiment today though. I tried running the heat on max both on and off the highway and I noticed that when I did this my temp started dropping not sure if this is just my heater core leaching heat from the coolant or something else but I just want to make sure I post all findings here.

88Dutchman

I live right up against the mountains west of Denver and my 88 ran hot all the time in the summer. I would be on edge every time I would take it into the mountains as it would come a few needle widths away from the red.


IMHO the expansion tank coolant system is a horrible system for the Jeep. There is a reason they changed it to a more modern conventional system after 95 was it? Also I think the stock radiators from 87 to 95 were thinner too but I'm not 100% sure on that.


Anyway I got tired of worrying about it so here is what I did. I got a 95 Cherokee radiator, a 145 deg thermostat and a universal overflow bottle.


Install those and loose the expansion tank. Since then I never worried about driving it in the mountains even on hot summer days.


Also it has never gone beyond a needles width past the half way mark (knock on wood). 90% of the time is just past the 1/4 mark.


That's what has worked for me anyway.


In your case I would try two things first.


One, make sure you don't have any air pockets in your coolant system. The reason I say that is my wife's Mini cooper has the same type of expansion tank system and she had the same problem. It turns out that there was a procedure to get rid of air pockets with a closed expansion tank type system after a fluid change. The garage that changed the radiator fluid did not bleed the air properly until we took it to a dealer. They got rid of the air pockets and after that it was fine. They did not even charge us anything for doing that either.
Not sure on how to go about it with the Jeep setup because there are no air bleeder valves like on the Mini but it may be worth a thought.


Second I would simply get a lower temp thermostat. If everything else is in order and you know there are no blockages it should make a difference.


If you still have an overheating issue I'd look into the radiator and if it turns out that its plugged or restricted in some way, simply go the 95 and newer route and not look back.


The coolant system is really not that complex of a system and I'm willing to bet with your current setup it's either an air pocket or restriction someplace.

getandistr

thanks for the suggestions Dutchman. The only thing is mine is already converted to the open system.

I got an IR gun and warmed up the jeep then let it sit for about 5-10 minutes to make sure all the temps were stable. It is currently 62F outside, my temp on the engine (between the T-stat housing and the water pump) was 187F, my temp on the T-stat housing was 132F and my temp on the Radiator was 82F. All the while my readout inside the jeep was ~200F.

Just in case I ordered a new radiator which will be coming in next week. I got a CSF 3 row radiator. But until then is there any other possible options? I just want to troubleshoot anything else until the radiator comes.

getandistr

So I ran the heat driving home and again the temp stayed at or below 210. Gonna try again tomorrow when it's going to be hotter. This is making me think it really something partially blocked and the extra demand from cooling the car and feeding the heater is forcing it through faster. Hopefully it's in the radiator and getting the new one will fix this once and for all.

Does that make sense to anyone else?

getandistr

Problem fixed!

So before I did anything else the engine temp fixed itself. It was driving at 210 except for when climbing a steep hill then it would rise to about 225. After the new radiator and 180 degree thermostat the engine holds between 190-200 but still goes to 215 on hills. I am guessing this is because I still have stock gearing on 33's. I'm going to just start a new thread for the oil issue.