High idle temps

[Spyro29]

Hey all,
I've got an 04' TJ 4.0l that likes to sit about a needles width above 210 degrees when it's sitting still/idling. When moving it drops to what is normally below 210.

I checked that the fan clutch seems to be working correctly. I've read that the fan should pretty much immediately stop when the jeep is turned off at high temp. Mine does. I can move the fan by hand when the engine is cold but it doesn't spin freely. That also seems to mean it's working from what I've read ya?

I do smell coolant when it's running so that makes me think it could be something more than just a fan or lack of airflow issue. There is an aftermarket radiator in it now and I can't help but think that could be the problem. The jeep never actually overheats or boils over, or at least it hasn't yet. It just likes to rise to that higher temp above 210 when idling and it can't be good long term.

I'm thinking about doing the radiator back to an OEM one, but should I also do the water pump too if I can smell coolant? Is it better to just do radiator/water pump/thermostat all at once if I'm already swapping radiators?

 

[macleanflood]

First thing you want to verify is that the ODB data lines up with the dash. A Bluetooth ODB dongle and the free app Torque Lite would let you monitor engine temp.

You then want to verify those numbers with a $20-30 IR gun on the thermostat housing.

I'd also suggest a pressure test to see if you can hold 18 psi and probably a combustion gas test next if you don't spot the hole or it's holding pressure.

If you're replacing the radiator a lot of us are having good luck with CSF and Koyorad. Robert Shaw thermostat too from Flowkooler.

-Mac

 

[Spyro29]

First thing you want to verify is that the ODB data lines up with the dash. A Bluetooth ODB dongle and the free app Torque Lite would let you monitor engine temp.

You then want to verify those numbers with a $20-30 IR gun on the thermostat housing.

I'd also suggest a pressure test to see if you can hold 18 psi and probably a combustion gas test next if you don't spot the hole or it's holding pressure.

If you're replacing the radiator a lot of us are having good luck with CSF and Koyorad. Robert Shaw thermostat too from Flowkooler.

-Mac

Alright thanks. I appreciate the tips. Ya it's been sorta strange, the jeep had low coolant in the reservoir when I bought it. I do smell coolant like I said, but it's not dripping anywhere obvious when parked.... When it's cool and I check the radiator it seems like some fluid should added because I don't see the coolant. Makes me wonder if it's not pulling from the reservoir.

 

[macleanflood]

Makes me wonder if you need a head gasket.

-Mac

 

[Spyro29]

Makes me wonder if you need a head gasket.

-Mac

Ya that was in the back of my mind for sure. I guess I was hoping it could be one of the other less expensive issues that you find all over online like, fan issue, stuck thermostat, clogged radiator, etc... but honestly all of that stuff seems to be fine which kinda leaves a head gasket issue.

 

[macleanflood]

Head gaskets are pretty easy as long as you don't discover more bad stuff like a cracked head.

Hardest part of a head gasket in getting the exhaust off.

-Mac

 

[Spyro29]

Head gaskets are pretty easy as long as you don't discover more bad stuff like a cracked head.

Hardest part of a head gasket in getting the exhaust off.

-Mac

Well I think I found what is good news compared to a bad head gasket. I was changing the oil and saw no signs of gasket issues. Coolant doesn't seem to show signs of mixing oil anywhere either. There does appear to be a slow oil leak towards the back of the motor but i really just think that's older seals on a 20+ year old car.

What I did finally see after topping off the radiator directly with fluid is that it leaks at the bottom of the radiator I can see it dripping out at the bottom between the fan shroud and the radiator. I can't seem to find a single hose leaking. I also don't see any signs of leaking at the water pump or thermostat or anything so that leads me to believe the radiator itself is leaking. Couldn't that be the cause of high idle temps?

 

[tr21triton]

I wouldn't be worried about a needle width above 210 when idling. I'd say it is doing what it supposed to do. That's what mine does especially if the ac is on.

 

[macleanflood]

But I would confirm those temps with live ODB data and an IR thermometer.

If the radiator is leaking I'd confirm with a pressure test and replace.

And the oil leak at the back of the engine is typically the valve cover gasket - start there - or the rear main seal. Sometimes rear main leaks go away by using high mileage convention oils.

-Mac

 

[Spyro29]

Just writing a conclusion to this thread. Did a cooling system flush, replaced the radiator and also needed a thermostat because there was a small leak in the gasket. Problem solved! Thanks for the help and replies on this one. Helped me get pointed in the right direction.

My next job will likely be replacing rear axle seals... Pretty confident I can do everything but the press part so I'll take it to a shop and have them press for me. BFH garage on YouTube is the shit. Highly recommend those vids if you have a TJ

Also need fluid flushes in transfer case and transmission but we'll see if I try those myself

 

[JKP]

The Tcase and MT are nothing more than: remove fill plug, remove drain plug. replace drain plug, fill with fluid. replace fill plug.