Process of elimination

[Wild Bill's ‘98 TJ]

Help!
My 1998 TJ is overheating (only at idle). Takes a few minutes after sitting at a drive through, traffic jam, etc. Cools down as soon as I’m moving again. I was convinced it was the fan clutch. Replaced it, same problem. Then I changed the thermostat, same problem. I’ve seen post saying heater core, radiator clogged, and water pump bad. I’m Frustrated. Anyone?
Thanks!!

 

[Jezza]

Help!
My 1998 TJ is overheating (only at idle). Takes a few minutes after sitting at a drive through, traffic jam, etc. Cools down as soon as I’m moving again. I was convinced it was the fan clutch. Replaced it, same problem. Then I changed the thermostat, same problem. I’ve seen post saying heater core, radiator clogged, and water pump bad. I’m Frustrated. Anyone?
Thanks!!

Take some temp readings when it is getting hot. Radiator top tank, bottom tank, thermostat housing and block. That will give a better picture of where the problem exists.

 

[ColoJeep]

Take some temp readings when it is getting hot. Radiator top tank, bottom tank, thermostat housing and block. That will give a better picture of where the problem exists.

Additionally , is it pukeing coolant out of or boiling in the overflow reservoir ?

 

[Jerry Bransford]

Is the fan shroud fully intact and installed?

 

[NskLJ]

Help!
My 1998 TJ is overheating (only at idle). Takes a few minutes after sitting at a drive through, traffic jam, etc. Cools down as soon as I’m moving again. I was convinced it was the fan clutch. Replaced it, same problem. Then I changed the thermostat, same problem. I’ve seen post saying heater core, radiator clogged, and water pump bad. I’m Frustrated. Anyone?
Thanks!!

Check the front side of the radiator between the condenser for debris also.

 

[Wild Bill's ‘98 TJ]

Take some temp readings when it is getting hot. Radiator top tank, bottom tank, thermostat housing and block. That will give a better picture of where the problem exists.

Thanks. Will do tomorrow.

 

[Wild Bill's ‘98 TJ]

Is the fan shroud fully intact and installed?

Yes sir. Perfect condition and installed correctly.

 

[Wild Bill's ‘98 TJ]

Check the front side of the radiator between the condenser for debris also.

No debris. Very clean. Never even been off road.

 

[Wild Bill's ‘98 TJ]

Additionally , is it pukeing coolant out of or boiling in the overflow reservoir ?

No pukeing, or boiling in reservoir.

 

[Wild Bill's ‘98 TJ]

Help!
My 1998 TJ is overheating (only at idle). Takes a few minutes after sitting at a drive through, traffic jam, etc. Cools down as soon as I’m moving again. I was convinced it was the fan clutch. Replaced it, same problem. Then I changed the thermostat, same problem. I’ve seen post saying heater core, radiator clogged, and water pump bad. I’m Frustrated. Anyone?
Thanks!!

UPDATE:
Flushed heater core, flushed radiator, flushed reservoir, and although I thought the radiator coils were squeaky clean, I flushed repeatedly from both directions and saw nothing but full flow clear water.
Refilled/burped with Zerex G05. Drove a few miles, came back home and parked in the boiling sun for over 20 minutes. Never got over 212-215. Previously, it would have ran hot after 5-6 minutes of idle. I hope that’s it. The only thing I haven’t done is a water pump.
Feel free to reply with opinions/comments. We all learn when you do.
Thanks!!

 

[Wild Bill's ‘98 TJ]

UPDATE:
Flushed heater core, flushed radiator, flushed reservoir, and although I thought the radiator coils were squeaky clean, I flushed repeatedly from both directions and saw nothing but full flow clear water.
Refilled/burped with Zerex G05. Drove a few miles, came back home and parked in the boiling sun for over 20 minutes. Never got over 212-215. Previously, it would have ran hot after 5-6 minutes of idle. I hope that’s it. The only thing I haven’t done is a water pump.
Feel free to reply with opinions/comments. We all learn when you do.
Thanks!!

Also temp sensor. Haven’t changed that or water pump.