Hey bought a '94 Grand Cherokee (4.0 I6) back in January. w/134,000m solid and runs good. There are a few wiring issues that I have yet to address, I bought this more a second vehicle then a DD. The Oil Pressure gauge pegs when the key is turned forward, but before the engine is turned over/running, also the Volt Meter shows low, a test at the Batt shows 14.5V so I know the Alts (unlike my wife) is putting out. The Power Mirror switch works backwards from the drives side to the passengers side. When switched to the passengers side it opps fine when on the drives position the left/right are Opp. Just some things but none are really anything that needs addressing right now.

Now the temp gauge has always been showing low maybe 175-180 and I'd read that a lot of Cherokees run hot so they change the thermostat to a cooler one. I thought that may have been the case with this one. Now not being a daily driver it gets a round trip back and forth to work each week. Last weekend w/temps in the 90° range I used it to take stuff to a wedding, I stopped on the side of the road to help a stranded motorist and when I got back to the jeep which had been idling with the A/C on for about 20 minutes, the temp must have been in the 220° range (way past the half way mark). As soon as we got moving again on the Highway (65mph) the temp dropped right back down to where it normally is on the gauge. Yesterday we had upper 90's again and I used the Jeep to cart some friends out to dinner, now in bumper to bumper traffic the needle started to climb, and with the A/C on the Jeep seemed to idle very low but more smooth then normal??? I plan after work today to use a temp gun and see what temps the engine is getting up to. I figure I'll take temps near the T-Stat housing, and at the sensor as well as the radiator.

I'd read through a number of post here and didn't seem to find any that really matched this issue so here it is. I had thought of doing some "Upgrades" to the Jeep over time and I figure a 3-core Radiator couldn't hurt, and might get the temp to stay more constant.
Anyone have any suggestion on what I'm looking at?
Thanks in advance for any comments.

 

Besides a few small issue's you seem fine, and when idling on the roadside or in traffic thats normal remeber your not moving to push air over the rad and engine, if you wish to upgrade wont hurt look at HESCO INC . com they have a high flow waterpump and t-stat housing and if you put that with a aluminium 2 or 3 row rad it will work wonders abit more money but I did it and haven't had a problem with my 2000 xj in 2yrs, good luck let me know if you got anymore questions.Two more things make sure your condensor for the a/c is clean and if you dont have a tranny cooler get one this will also help with the cooling a bit.And the myth of a 180 or a 195 t-stat is that a myth personal choice.

 

sounds like you need a new fan clutch...when temp creeps up at idle or heavy traffic is usualy a sign of a bad fan clutch. do you have the stock fan shroud installed and in one piece?...dont change to a lower t stat stick with a 195. You may want to go thru the entire cooling system I see SOO MANY o/heat threads here...250.00 will fix most (barring head gasket issues) over heating issues. new radiator,fan clutch,tstat (195) and water pump and a GOOD flush WILL fix these issues...
Cameron

 

You could have a brand new clutch fan and your temp will still climb sitting still ,your not really overheating that I can see atleast you haven't said so. But yes if your fan clutch is old to you replacement is a good idea.I haven't seen a car truck rig etc that the temp doesn't climb some when at a standstill or in heavy traffic surrunded by other cars truck etc.

 

well then I guess my jeep is a odity..since changing out the parts previously mentioned my Temp doesnt move at idle or in traffic,wheelin etc. It does move a tad when pulling a long hill at highway speeds out here in the desert 110+..sorry but your statement that you have never seen a car or rig not rise at idle is pretty general.
infact ALL my vehicles i have now dont including my 47 flathead!


Cameron

 

Well its been a while and I'm back. The other night on the way home, on the highway I started to overheat. It was low 30's out I was close to home. I got off at the next exit and the needle really started to move. By the time I pulled into a parking lot the needle was pegged and the jeep stalled so I coasted to a spot. Got out and saw anti-freeze dripping away from the radiator. Walked home.

Next day bought a new rad and Saturday installed it. I was able to fire the jeep the next day while it was cold I put about 1 gallon of water in and it didn't take the whole gallon so I don't think I lost too much.

Now I replaced the rad not too bad the trans lines are their own story. I have started it and got it up to 210* drove it around the neighborhood and it went to the next mark on the gauge above the 210*. I shut it off and let it cool, it sucked down some coolant and the overflow was empty. I topped the over flow off. Let it cool and took it out again. Now it did the same thing. never really going much above the mark/line beyond the 210* line. So I parked and let it cool. It doesn't look like it took much more coolant. I have done the dive cool thing about 6-7 times now and it doesn't seem like its taking any more so the air should be gone right.

Temp gauge stays pretty steady around the mark/line past 210* (normally before it was below the 210*)
Radiator is new so is the lower hose. I did put the spring form the old in the new since it didn't come with one.
Fan Clutch looked clean when radiator was out, is stiff when cold.
Upper hose gets hot and has some pressure but feels kind of spongy.
Both heater hoses get hot and the cab has great heat. lower rad hose is cold and so is most of the radiator, the higher I touch the warmer it gets, only the very top does it burn the skin. This is after driving and getting it hot.
Radiator cap is 18psi.

Where to start looking? I've read that the T-Stat could fail on an over heat causing flow issues I'd think it would fail and in away that I'd have heating issues?

 

210 is normal. If I were you I would change the coolant and flush out the system. I would put in a new thermostat, and if you really want to eliminate everything do the water pump too. Just my 2 cents

 

Thanks took the bike out to clear my head. Stopped by and got a 16 psi cap and a thermostat w/a extra gasket.

Tried the cap and it seemed OK for while driving then it went a line/bar/mark beyond the one it had been at, so now its two lines/bars/marks above the 210* it went the wrong way. I hope it let some air out and will suck in some from the over flow. I didn't have the heat on until after it hit the next mark. It didn't move the needle down at all. I sat at idle for another few minutes and it didn't go up any farther. Kind of weird.

The lower hose is still cold.

I wounder if the impeller is off the shaft? I'd read somewhere about that also it has a test in the service manual for that. Could it be and everything went at the same time??

 

Since you said you over heated it. Did you check your oil and see if you have any coolant in your oil. Hopefully not. If so you could have blown a head gasket. Also is the coolant level still dropping. If so that can be another indicator of a blown head gasket or even a cracked head. With a little luck that isn't you problem. But it is something you need to look into. Like I said, Check you oil for any signs of coolant in it and get back with us and let us know what you find and we can go from there.

 

Thanks RTorrez1 for the tip. So far it doesn't look like its taking anymore fluid from the over flow and I don't see anything so far on the cap. Looking at the oil on the stick it looks good.

So anyone have the shaft break on the pump? I hear a slight 'whine" on start up and at idle that I hadn't had before. I don't think. It actually sounds like its coming from the alt so may be unrelated and I'm being paranoid. 'Blip" the throttle and it goes right away, comes back and after just a few minutes is quiet. So I don't know.

I've got Jury Duty today so I may get a chance to work on it this afternoon. I'm going with the t-stat. I bought it at Car Quest they said its made by Stant. Anyone have any luck good or bad? Could I shooting myself in the foot with it?

 

Here is your clue: "The lower hose is still cold.".
Water pump = $35

 

Kalali I didn't want to hear that but that's what I was thinking, Looks like a lot to get it in. I'm thinking the shaft and impeller are no longer attached.

Thanks I'm not gonna bother with the T-Stat then and see. I'll do them both at the same time. Hey at least the weathers warmer and sunny.

 

Well after a crappy week on jury duty I planned to change the water pump and thermostat today. I had also planned to have new tires mounted on the sportster too. That blew up in a bad way. Let just say I didn't get started until late this afternoon.(Sat) T-stat was bought at Car Quest and while I was told it was made by Stant it looks pretty cheap and doesn't have the rivet like the one I'm removing. I pulled the radiator to make the job a bit easier yet maybe not. I cut the crap out of my forearms on the evap coil.

So I got the fan off, belt off, and went right for the Water Pump. Not bad at all getting there once you get the Power Steering Pump out of the way that is made easier by pulling the air box. Well I was super disappointed to find that in fact the Water Pump was fine the impeller was still firmly pressed on to the shaft. I pulled of the Tsat housing and checked out the old Tstat and didn't see anything right off. I was hopping for that Ah Ha moment and I didn't get it. Started to get late and I managed to get the Pump and Tstat installed before dark. Plans to finish in the a.m.

While doing some more searching I found a youtube on tstat's and cooling systems in general that said hot upper hose, cold or cool lower hose yet over heating "It will be a mechanical failure of the Tstat closed."

Well I got up this morning to install the radiator and the rest and give it a test run. I buttoned it all up and took a second look at the tstat and it turns out that yes it had failed in the close position.

So far I drove it around and it stayed in the normal range (for me) a bar under the 210 or half way mark. I'm letting it cool hoping it'll suck down some coolant from the overflow jug.

Thanks for everyone's input. I now have a used in good condition Water Pump if anyone in the western burbs of Chicago needs one. I also bought a spare gasket JIC so if it doesn't leak soon the old one will come with a new gasket.