Still gettin' hot!
CF Veteran
Joined: Nov 2009
Posts: 8,172
Likes: 17
From: The Republic of TEXAS
Year: 1998
Model: Cherokee
Engine: 4.0L HO
...... still scratchin' my head. 0bviously the ScanGauge won't have any affect on the cooling system but it's still handy as a pocket on shirt on just about any '96 up vehicle.
Thread Starter
Junior Member
Joined: Oct 2012
Posts: 44
Likes: 0
Model: Cherokee
Put a new 180 degree stat in last week, and diluted the coolant a bit with distilled water. Temp now runs around 180-190 in local driving including stop and go, climbs to near 210 going up long canyon roads. Haven't yet taken it on a long highway run to see if it still overheats. The thermostat I replaced had an overheat limp-home feature where it locked open if that was tripped, which it was. I also ran an exhaust gas/coolant test that came back negative, so the cracked head or leaking head gasket isn't very likely.
CF Veteran
Joined: Nov 2009
Posts: 8,172
Likes: 17
From: The Republic of TEXAS
Year: 1998
Model: Cherokee
Engine: 4.0L HO
Keep us posted. IMO, those "fail-safe" t-stats r nothing more than a marketing/advertising "gimmick". Nothing garantees that they open and that's all that matters.....that it opens. Once the stat opens and a overheat occurs, it's obvious that something else (not the stat) is causing the overheat.
Seasoned Member
Joined: Mar 2010
Posts: 290
Likes: 0
From: steilacoom washington
Year: 1990
Model: Cherokee
Engine: striaght 6 4.0l
I had the same problem last two years just two weeks Ago a buddy of mine who works for orielys told me run open t stat . I said no I'm not doing that . But he said give this a try pull the guts out of the t stat with like an old so it gives you so type of pressure in your system it will take longer to warm up but your coolant will always be flowing more freely and not being restricted as much . I did and seems to be running just fine and just takes longer for hot air in the cab but doesn't get over 210 so far I wanna put this to the limits when I go wheeling again and see how we'll it works
CF Veteran
Joined: Nov 2009
Posts: 8,172
Likes: 17
From: The Republic of TEXAS
Year: 1998
Model: Cherokee
Engine: 4.0L HO
I had the same problem last two years just two weeks Ago a buddy of mine who works for orielys told me run open t stat . I said no I'm not doing that . But he said give this a try pull the guts out of the t stat with like an old so it gives you so type of pressure in your system it will take longer to warm up but your coolant will always be flowing more freely and not being restricted as much . I did and seems to be running just fine and just takes longer for hot air in the cab but doesn't get over 210 so far I wanna put this to the limits when I go wheeling again and see how we'll it works
If u want to do a short term experiment comparing using a stat vs no stat, just take the stat out.....don't waste your time ruining a good stat by tearing it apart. A stat vs no stat test is worthless unless the comparison is done under identical operating conditions.....same ambient temp, driving conditions, etc.
I would be willing to say that 999 times out of 1000, the stat is not the cause of overheating. The sole purpose of the stat is to raise coolant temp as quickly as possible up to the normal operating temp range. Operating a motor too cold, too long, is almost as bad as overheating.
Where u live (cold/cool ambient temps), I'd bet u r doing your motor more harm than good by running no, or a rigged, t-stat.
Last edited by djb383; May 20, 2013 at 09:27 AM.
Herp Derp Jerp
Joined: Nov 2011
Posts: 18,251
Likes: 17
From: Parham, ON
Year: 1999
Model: Cherokee
Engine: 4.0L OBD-II
It's worth mentioning in here that a lower opening T-stat will of course impact fuel efficiency, and possibly the longevity of other parts, however its effects are only observable in certain conditions. Your mechanical and electric fans are still coming on at the same temp. A lower temperature thermostat does notimprove the ability of the radiator or fans to remove heat from the system. You're going to have the same max temperature with whatever thermostat you run: The T stat is good for only the minimum temperature, nothing else. (Unless of course it's failed shut.) The AMC and Chrysler FSMs make it quite clear as to what the minimum should be.
CF Veteran
Joined: Nov 2009
Posts: 8,172
Likes: 17
From: The Republic of TEXAS
Year: 1998
Model: Cherokee
Engine: 4.0L HO
If I'm understanding oneal916 correct, he has "gutted" his t-stat which is the same thing as "no t-stat". Not good.
Chrysler did offer a Mopar/Jeep 180F stat for the XJ, in some areas, thru the dealerships. A 180 was never installed at the factory. I'll see if I can locate the part #.
We run a 180 year round and it does allow for slightly lower operating temps I'd say/guess 95% of the time.....it depends mostly on what the ambient temp is. Cool/cold ambient temps, especially when running the heater, actual coolant temp will be at, or very close to, the t-stat rated temp.....in warm/hot ambient temps, coolant temp can be well above t-stat rated temp. Actual coolant temps fluctuate/vary over the course of a year (ambient temp changes) despite the goofy and rigged factory gauge always pointing at 210. Once the t-stat has reached it's "fully open" position (usually at +/-15* above rated temp), it no longer controls anything to do with coolant temp.
Chrysler did offer a Mopar/Jeep 180F stat for the XJ, in some areas, thru the dealerships. A 180 was never installed at the factory. I'll see if I can locate the part #.
We run a 180 year round and it does allow for slightly lower operating temps I'd say/guess 95% of the time.....it depends mostly on what the ambient temp is. Cool/cold ambient temps, especially when running the heater, actual coolant temp will be at, or very close to, the t-stat rated temp.....in warm/hot ambient temps, coolant temp can be well above t-stat rated temp. Actual coolant temps fluctuate/vary over the course of a year (ambient temp changes) despite the goofy and rigged factory gauge always pointing at 210. Once the t-stat has reached it's "fully open" position (usually at +/-15* above rated temp), it no longer controls anything to do with coolant temp.
Seasoned Member
Joined: Mar 2010
Posts: 290
Likes: 0
From: steilacoom washington
Year: 1990
Model: Cherokee
Engine: striaght 6 4.0l
Tell your buddy the FSM manual says "do not operate without a t-stat". One would presume the engineers that wrote the manual know what they're talking about, for the most part. Does your buddy know what he's talking about or is he just telling u something he read on the Internet? Tell your buddy that coolant is flowing/circulating thru the motor (block & head) the moment the motor is started, even when it's cold.
If u want to do a short term experiment comparing using a stat vs no stat, just take the stat out.....don't waste your time ruining a good stat by tearing it apart. A stat vs no stat test is worthless unless the comparison is done under identical operating conditions.....same ambient temp, driving conditions, etc.
I would be willing to say that 999 times out of 1000, the stat is not the cause of overheating. The sole purpose of the stat is to raise coolant temp as quickly as possible up to the normal operating temp range. Operating a motor too cold, too long, is almost as bad as overheating.
Where u live (cold/cool ambient temps), I'd bet u r doing your motor more harm than good by running no, or a rigged, t-stat.
CF Veteran
Joined: Nov 2009
Posts: 8,172
Likes: 17
From: The Republic of TEXAS
Year: 1998
Model: Cherokee
Engine: 4.0L HO
Sorry dude hope you didn't blow a head gasket it was just a suggestion hope your brain didn't fry from that . You know I thought this forum was for helping people and getting help from people not getting bombed cause a suggestion was made that may not be {the right way or the wrong sometimes you have try this and find out your self }
Herp Derp Jerp
Joined: Nov 2011
Posts: 18,251
Likes: 17
From: Parham, ON
Year: 1999
Model: Cherokee
Engine: 4.0L OBD-II
Sorry dude hope you didn't blow a head gasket it was just a suggestion hope your brain didn't fry from that . You know I thought this forum was for helping people and getting help from people not getting bombed cause a suggestion was made that may not be {the right way or the wrong sometimes you have try this and find out your self }
Of course it's the correct way, it's described in the specifications from the engineers that designed these things... These things ran fine from the factory. There's no reason at all to change anything outside of factory specs unless addressing a specific design flaw (for example, Renix closed cooling is a pain to deal with, adding an aux trans cooler). Often times people will think that they need some magic fixit or want to "improve" something when the reality is that their 15-20 year old vehicle just needs normal maintenance.
There are a lot of threads on here where people have wasted a ton of time and money trying to fix a problem that doesn't exist.
CF Veteran
Joined: Nov 2009
Posts: 8,172
Likes: 17
From: The Republic of TEXAS
Year: 1998
Model: Cherokee
Engine: 4.0L HO
I had the same problem last two years just two weeks Ago a buddy of mine who works for orielys told me run open t stat . I said no I'm not doing that . But he said give this a try pull the guts out of the t stat with like an old so it gives you so type of pressure in your system it will take longer to warm up but your coolant will always be flowing more freely and not being restricted as much . I did and seems to be running just fine and just takes longer for hot air in the cab but doesn't get over 210 so far I wanna put this to the limits when I go wheeling again and see how we'll it works
Again, the sole purpose of the t-stat is to allow the coolant/motor to heat up as quickly as possible. Once the t-stat is wide open, it does nothing and in the wide open position it will allow more coolant to flow than the water pump can push. If the motor overheats when the stat is wide open, it ain't the stat causing the overheat.
CF Veteran
Joined: Apr 2009
Posts: 4,734
Likes: 12
Year: 2015, 2012
Model: Grand Cherokee (WK2)
Engine: 3.6L
You people need to listen to djb383. He knows what he is talking about on this one.
Everything he is saying in his posts is absolutely correct. Whether you like it or not.
Everything he is saying in his posts is absolutely correct. Whether you like it or not.
CF Veteran
Joined: Nov 2009
Posts: 8,172
Likes: 17
From: The Republic of TEXAS
Year: 1998
Model: Cherokee
Engine: 4.0L HO
The t-stat slows coolant flow down because it is reacting/closing due to coolant from the block/head that has not been sufficiently heated (to the stat rating temp) by the motor. Coolant that flows by the stat is coolant that's leaving the motor, not the rad.
CF Veteran
Joined: Mar 2010
Posts: 47,923
Likes: 38
From: Broward County Fl.
Year: 1989 xj sport 2dr
Model: Cherokee
Engine: 12 hole bosch Injectors
I said that I thought ...lol...