M1008 Not Reaching Running Temp

It is winter here in Michigan and my truck does not go over 110 degrees. It has a new radiator, heater core and thermostat all with in this last year. Do I need to put cardboard up front or is there another issue?

Thanks

My guess is the thermostat is bad or the wrong one, even if it is new. If you do a lot of driving in colder temps, especially short hops, some cardboard or a 'winter front' won't hurt.

That sounds like it could be a bad or wrong thermostat. Where do you have your temp gauge sensor mounted? If in the water pump that would be the problem.

The gauge sensor is in the back of the motor right next to the firewall. It also has an Auto zone special radiator cap which reads the same thing.

Try the t-stat again, here in ak we like to use a 205 degree t- stat makes the heater work real good. I have had bad thermostat's com straight out of the box from reputable suppliers

Have you checked your clutch fan? I'm not sure about the ones on our trucks? But I know some of them fail locked, so as to not over heat the motor. Also, don't quote me on this but, I seem to remember that the coolant flows through the drivers side head first. If so that could also give a false reading. Unfortunately the only way to get a true over all reading is by swapping to a HMMWV coolant crossover tube. It has a bung just behind the thermostat for your temp sensor.

Block off the air flow a bit. It helps. That is a huge radiator up there and it looses heat in a big way. make your own cover. I have made several types and they fit the look well. I am putting my grill =e cover back on my M1009s this coming weekend. I just designed and built a new one. I will post pictures for sure.

I like to use pizza boxes!

cucvrus said:

Block off the air flow a bit. It helps. That is a huge radiator up there and it looses heat in a big way. make your own cover. I have made several types and they fit the look well. I am putting my grill =e cover back on my M1009s this coming weekend. I just designed and built a new one. I will post pictures for sure.

Click to expand...

This fixed my cooling issue -

Sharecropper said:

This fixed my cooling issue -

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I need to get one of those.
Using cardboard now.
It works, but do not like the look of it.

Blocking the cold air really makes a big difference.

I have an original military canvas cover but it don't fit any of my CUCV's because of the lights I installed. I now make my own.My Mule M1009 with a full bolt on radiator grille cover. Works very well. Also last year I made this cover out of fiberglass troop seat slats. it is a simple bolt on no holes drilled attachment. I store them under the hood in a small rack in the warm seasons. Happy Holidays.

a good thermostat and fan clutch and all that other stuff is unnecessary unless the weather drops to - 40

Not true. It still makes a world of difference in cold weather. These vehicles have no insulation on the cab anywhere. They have a heater that works very hard in an M1009 to heat that large cargo/passenger area. When it is 10 degrees out and you want to drive at 75 MPH on the interstate it works and hurts nothing. Even with a perfect running CUCV.

If I let the truck idle for a long period of time will will heat up to about 160

incomplete combustion will keep all diesels cold it not idled up to around 900 rpm. I live where its cold most of the year you are right about blazers an aux heater like the suburban has will help a lot. covering the radiator is a bad fix for a proper thermostat as the engine still wont warm up until you drive it down the road and as the over the road operators found when trying to zip out the center section it put un even loads on the fans and caused early failures. if using a bib over the front you want a centered vent or cut a draft hole in the center of the cardboard so you do get a little cooling out of it. If the cooling system is functioning properly, your hand should be uncomfortable when held over a defroster vent as you are running down the road.

If you want to check the thermostat, take it out & put in pot of water on stove with thermometer.

Running any motor below operating temp will eventually cause failure. The lube system will not work as designed and the combustion will be off. I buried a straight 6 Chevy gas motor on Rt 80, (in the 80s) was running with no heat in sub zero F temps, thermostat stuck open, figured I would be OK wearing my snow gear, did not know how bad it was for motor. I was OK until the engine dropped a valve due to poor lubrication due to cold. The rest is another story, but will never make that mistake again.

If you're going to boil a thermostat, put it in cold with a thermometer so you can monitor what temp it opens up.

You might also want to make sure you bleed the air from the rear of the engine, it will make your gauge read low. Run the engine and get it a little warm so it builds up some pressure, then crack the gauge sensor/bulb fitting to let the air escape. Just by careful of the pressurized coolant.

On on my truck the air pocket made a 30 deg difference on the gauge.

I cut out some cardboard and attached it to the grill and noticed the temperature was about 140° F. The outside temperature was 5° F. I still didn't get the heat I would like to have. I guess its time to check the thermostat

When I first put in my temp gauge, it would only get to around 160. Thought it was the thermostat, so I changed it out for a new 195. Still read 160-170 at the rear of the engine. The cardboard helps to keep it at 170ish at temps below 32 f.