I am stuck with my 98 XJ cooling system
Senior Member




Joined: Jun 2019
Posts: 634
Likes: 182
From: Northern California
Year: 1999
Model: Cherokee (XJ)
Engine: 4.0 w/ Banks header & K&N intake
I will test to see if there is combustion and go from there. There’s still a lot to be done
I just want to drive it in all seasons without worry. AC on when I want
I just want to drive it in all seasons without worry. AC on when I want
Last edited by Kosta0933; Sep 24, 2024 at 08:44 PM.
Your fan clutch PULLEY will always run, but it should not be magnetically engaged, it should cycle on/off, with an interval anywhere between 10-60 sec, so easily observable.
If any other situation exists, there is a fault, see FSM fault finding chart
* Read actual engine coolant temp with a plug in OBD2 reader and free Torque Lite app on phone (mine is permanently fitted BAFX $30)
I use OEM style rad cause they are cheap, fit, and dont seem to be any less reliable than other designs. I remain to be convinced aftermarket designs offer improved cooling, but I may be wrong.
I do feel the OEM design is marginal for hot weather, (like many vehicles)
My system does not normally overheat, we get 110F weather, summer is hot in Australia
It runs as per the specs in FSM for fan operation (105-108C)
Engine normally runs at thermostat temp which is 82C
It goes to 105C when almost immediately when idling. The electric fan keeps it there, and switches on/off
When it is really hot/towing/low speed off-roading, one must monitor engine & trans temp gauge
One can fit a more powerful VC fan, I believe it is for the smaller engine XJ. Some guys report removing its as its noisy
All fan shroud's should be properly fitted, they make a big difference
A good rad cap is a must
If water pump is unknown, fit a new one, they are cheap as dirt
I recommend pressure test your cooling system, very cheap test.
If you have no bubbles in filled rad neck, will NOT be head gasket. There should be almost to no bubbling once its warm. Salad cream in the oil fill cap is the other giveaway.
AW4 tends to run near engine temp with rad fiiting, even with much larger air cooler. This is not ideal in a hot climate and shortens their life or even destroys them if not very careful. I have a trans temp gauge
Apart from that, the only issue is whether the block has lots of scum, but we will leave that
sorry bout the C stuff, we left the F stuff behind 50yrs ago, when i was still in skool
If any other situation exists, there is a fault, see FSM fault finding chart
* Read actual engine coolant temp with a plug in OBD2 reader and free Torque Lite app on phone (mine is permanently fitted BAFX $30)
I use OEM style rad cause they are cheap, fit, and dont seem to be any less reliable than other designs. I remain to be convinced aftermarket designs offer improved cooling, but I may be wrong.
I do feel the OEM design is marginal for hot weather, (like many vehicles)
My system does not normally overheat, we get 110F weather, summer is hot in Australia
It runs as per the specs in FSM for fan operation (105-108C)
Engine normally runs at thermostat temp which is 82C
It goes to 105C when almost immediately when idling. The electric fan keeps it there, and switches on/off
When it is really hot/towing/low speed off-roading, one must monitor engine & trans temp gauge
One can fit a more powerful VC fan, I believe it is for the smaller engine XJ. Some guys report removing its as its noisy
All fan shroud's should be properly fitted, they make a big difference
A good rad cap is a must
If water pump is unknown, fit a new one, they are cheap as dirt
I recommend pressure test your cooling system, very cheap test.
If you have no bubbles in filled rad neck, will NOT be head gasket. There should be almost to no bubbling once its warm. Salad cream in the oil fill cap is the other giveaway.
AW4 tends to run near engine temp with rad fiiting, even with much larger air cooler. This is not ideal in a hot climate and shortens their life or even destroys them if not very careful. I have a trans temp gauge
Apart from that, the only issue is whether the block has lots of scum, but we will leave that
sorry bout the C stuff, we left the F stuff behind 50yrs ago, when i was still in skool

Your fan clutch PULLEY will always run, but it should not be magnetically engaged, it should cycle on/off, with an interval anywhere between 10-60 sec, so easily observable.
If any other situation exists, there is a fault, see FSM fault finding chart
* Read actual engine coolant temp with a plug in OBD2 reader and free Torque Lite app on phone (mine is permanently fitted BAFX $30)
If any other situation exists, there is a fault, see FSM fault finding chart
* Read actual engine coolant temp with a plug in OBD2 reader and free Torque Lite app on phone (mine is permanently fitted BAFX $30)
what about the AC clutch? Should that be constantly spinning while the AC is on? I thought those were intermittent. Mine is constantly spinning when AC
is on. It doesn’t move when I turn off the Ac.
I will use a OBD2 reader and report back
Senior Member




Joined: Jun 2019
Posts: 634
Likes: 182
From: Northern California
Year: 1999
Model: Cherokee (XJ)
Engine: 4.0 w/ Banks header & K&N intake
Last edited by Very Red XJ; Sep 25, 2024 at 10:49 AM. Reason: correct
Senior Member




Joined: Jun 2019
Posts: 634
Likes: 182
From: Northern California
Year: 1999
Model: Cherokee (XJ)
Engine: 4.0 w/ Banks header & K&N intake
Your fan clutch PULLEY will always run, but it should not be magnetically engaged, it should cycle on/off, with an interval anywhere between 10-60 sec, so easily observable.
If any other situation exists, there is a fault, see FSM fault finding chart
* Read actual engine coolant temp with a plug in OBD2 reader and free Torque Lite app on phone (mine is permanently fitted BAFX $30)
I use OEM style rad cause they are cheap, fit, and dont seem to be any less reliable than other designs. I remain to be convinced aftermarket designs offer improved cooling, but I may be wrong.
I do feel the OEM design is marginal for hot weather, (like many vehicles)
My system does not normally overheat, we get 110F weather, summer is hot in Australia
It runs as per the specs in FSM for fan operation (105-108C)
Engine normally runs at thermostat temp which is 82C
It goes to 105C when almost immediately when idling. The electric fan keeps it there, and switches on/off
When it is really hot/towing/low speed off-roading, one must monitor engine & trans temp gauge
One can fit a more powerful VC fan, I believe it is for the smaller engine XJ. Some guys report removing its as its noisy
All fan shroud's should be properly fitted, they make a big difference
A good rad cap is a must
If water pump is unknown, fit a new one, they are cheap as dirt
I recommend pressure test your cooling system, very cheap test.
If you have no bubbles in filled rad neck, will NOT be head gasket. There should be almost to no bubbling once its warm. Salad cream in the oil fill cap is the other giveaway.
AW4 tends to run near engine temp with rad fiiting, even with much larger air cooler. This is not ideal in a hot climate and shortens their life or even destroys them if not very careful. I have a trans temp gauge
Apart from that, the only issue is whether the block has lots of scum, but we will leave that
sorry bout the C stuff, we left the F stuff behind 50yrs ago, when i was still in skool
If any other situation exists, there is a fault, see FSM fault finding chart
* Read actual engine coolant temp with a plug in OBD2 reader and free Torque Lite app on phone (mine is permanently fitted BAFX $30)
I use OEM style rad cause they are cheap, fit, and dont seem to be any less reliable than other designs. I remain to be convinced aftermarket designs offer improved cooling, but I may be wrong.
I do feel the OEM design is marginal for hot weather, (like many vehicles)
My system does not normally overheat, we get 110F weather, summer is hot in Australia
It runs as per the specs in FSM for fan operation (105-108C)
Engine normally runs at thermostat temp which is 82C
It goes to 105C when almost immediately when idling. The electric fan keeps it there, and switches on/off
When it is really hot/towing/low speed off-roading, one must monitor engine & trans temp gauge
One can fit a more powerful VC fan, I believe it is for the smaller engine XJ. Some guys report removing its as its noisy
All fan shroud's should be properly fitted, they make a big difference
A good rad cap is a must
If water pump is unknown, fit a new one, they are cheap as dirt
I recommend pressure test your cooling system, very cheap test.
If you have no bubbles in filled rad neck, will NOT be head gasket. There should be almost to no bubbling once its warm. Salad cream in the oil fill cap is the other giveaway.
AW4 tends to run near engine temp with rad fiiting, even with much larger air cooler. This is not ideal in a hot climate and shortens their life or even destroys them if not very careful. I have a trans temp gauge
Apart from that, the only issue is whether the block has lots of scum, but we will leave that
sorry bout the C stuff, we left the F stuff behind 50yrs ago, when i was still in skool

Junior Member
Joined: Nov 2021
Posts: 91
Likes: 11
From: R/K WI.
Year: 2001
Model: Cherokee (XJ)
Engine: 4.0 i6
Aw4 is comfy 180 to 220. So, with it plumbed into rad it will easily see 195 to 210 daily. Electric fans kick on to help cool then shut off.
Running a/c contributes more heat. I see very Lil to raise an eyebrow here. If your uncomfortable with 220 add hood vents. Jmho
Running a/c contributes more heat. I see very Lil to raise an eyebrow here. If your uncomfortable with 220 add hood vents. Jmho
Junior Member
Joined: Nov 2021
Posts: 91
Likes: 11
From: R/K WI.
Year: 2001
Model: Cherokee (XJ)
Engine: 4.0 i6
Oh and change Trans fluid more frequently. This ain't rocket science lol just a jeep.
Now if your cooking 230 to 250 well then you would probably wanna get some issues sorted out.
You stated 220 was your high temp reading.
Now if your cooking 230 to 250 well then you would probably wanna get some issues sorted out.
You stated 220 was your high temp reading.
Last edited by BlueBalls; Sep 26, 2024 at 02:40 AM.
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