Excessive Run Temp HMMWV

[Blizken]

I've read all the threads I think regarding this super common problem of having the HMMWV run hot.

06 HMMWV 6.5
Aftermarket radiator and tank (pics) were installed less than 500 miles ago.

Problem
Runs from cold start to 240 or just below. 240 and 240 plus under driving load. At between 220-240 fan engages momentarily, runs for a bit and then disengages.
Idle engine temp around 220-240.

When I unplug the TDS (full time fan engaged) , settles to around 190ish.

To date I have:
Removed thermostat. Bench test=faulty. Running temporarily with no thermostat.
Disconnected Cad Valve-Fan engages. Cad valve Ohms test 91 both ways.
Disconnect TDS-Fan engages.
Disconnected Thermostatic Switch-Fan engages. Also just replaced this switch with OEM "black" version.
Added 2 bottles water wetter
Confirm fan is proper direction for serpentine.



Things I have not done yet but will be doing next:
Change oil.
Flush radiator.
Add distilled water 80% and Water Wetter. 20% Antifreeze. (I live in the Mojave).
Replace Cadillac Valve.
Replace TDS
Replace Temp sending unit to gauge with OEM.
Replace temp gauge with Clark Brothers.

Questions for the Brain Trust:
1. Can the water pump be bad? The upper radiator hose is never hard-I can squeeze it and bring both sides to touch but it's very hot and I am pretty sure I can feel fluids going through it. I do not know how to test a water pump.
2. Other than unplugging the TDS permanently, which will solve this problem-can the TDS or Cad Valve be coaxed etc into bringing the fan on earlier?
3. Am I right in assuming the thermostatic fan switch tells the fan systems to come on? If so-since I just replaced this than there is nothing else i can do with that right?

Any other ideas you have would be appreciated.

I should note that I am replacing the temp sending unit and temp gauge just in case it makes different readings than what I presently get. If by some miracle the temp readings are way lower -then this is all for nought.

Thanks in advance for your help.

Cheers.

 

[SmartDrug]

Have you hit the thermostat with a IR Thermometer to confirm temps on the gauge?

From those symptoms, that would be my first guess.

 

[Sigi]

I'd install the OEM temp sender; needs to be matched to gauge. Then verify gauge by measuring actual temps with infrared thermometer.

 

[MarkM]

Mine runs between 220 to 235. Just the way these things are. I would love to get her down to 190 but oh well. If the water pump is spinning and no outside leaks then more than likely it's fine.. wish someone came out with a lower temp probe switch..

Mark

 

[Mogman]

Sounds pretty normal to me, not sure why all the effort to fix what is normal

 

[Blizken]

Sounds pretty normal to me, not sure why all the effort to fix what is normal

Have you hit the thermostat with a IR Thermometer to confirm temps on the gauge?

From those symptoms, that would be my first guess.

I will make that happen today. Thanks.

 

[Blizken]

Mine runs between 220 to 235. Just the way these things are. I would love to get her down to 190 but oh well. If the water pump is spinning and no outside leaks then more than likely it's fine.. wish someone came out with a lower temp probe switch..

Mark

Noted. It's nice to know about the common baseline. After I finish everything then I am just going to accept the results. As long as I'm not alone with this-thats cool.

 

[Gcelevator]

My gauges shows 230-240 but with an infrared temp gun the highest temp was 198 degrees. I would check into it before driving yourself nuts.

 

[Retiredwarhorses]

Have you replaced you coolant bottle cap?
have you verified the cooling system is pressuring up? “Squeeze the upper radiator hose”
have you replaced the temp gauge?

 

[juanprado]

Is that an oe coolant bottle? Many have posted issues with the chinacom knock offs

 

[Blizken]

Is that an oe coolant bottle? Many have posted issues with the chinacom knock offs

I have no idea as it came with the truck.

 

[Blizken]

My gauges shows 230-240 but with an infrared temp gun the highest temp was 198 degrees. I would check into it before driving yourself nuts.

I am coming to the conclusion that its all fine. They just run hot. I put the IR on it and got 212 at the water pump-thermostat head.

 

[Gcelevator]

I am coming to the conclusion that its all fine. They just run hot. I put the IR on it and got 212 at the water pump-thermostat head.

Try different spots, like the reservoir tank, top of the radiator close to the hoses, thermostat housing, heads. I even tested the oil pan and transmission.

All will be fine.