M35 Operating temp??

[forklift]

Feeling stupid for this one. What should my truck run for a temperature? I took it for a spin today, looked down, and the temp gage was at or over 240. The fluid level is fine. Any Ideas????

 

[jld66]

Normal temp should be in the 180-185 range. It should take a lot of hard work in warm weather to get the Deuce temp much over that.

 

[cranetruck]

240F is not normal.
Check your gauge/temp sending unit.
The coolant should be replaced every two years or so, since it "wears out" even if the engine is not running. Fresh coolant with additives is more efficient than old.
Last summer driving up Black Mountain (I-40) in Western North Carolina with a load of lumber, my engine op temp reached 208F and that is the max I have ever seen in my deuce.
The gross vehicle weight was about 22,000 lb, the climb is a 5 mile long 5-7% grade and I had my radiator restictive cover installed (pictures elsewhere in several posts). When the road leveled out, the temp quickly returned to the normal 180-185.

For accurate temp monitoring, I use a thermocouple/DVM, but the dash gauge roughly agrees witht he readings on the DVM. Straight up and down the gauge reading is 176F and the T-stat hasn't even begun to open.

 

[Westech]

My sending unit went bad, very norm thing for them to do. good thing to do is take it out and clean it. The grime sometimes builds up on the brass and givea a bad reading. As 240* you better hope not thats a tad hot for a diesel!! I got my deuce over 190 one time, driving up the hills in western Wisconsin. Full load of fire wood and I forgot to remove the front cover on the grill. Other then that I have really pounded that multi and it make leak a tad here and there but she always comes back for more.

 

[Recovry4x4]

I need one of them myself. You would be hard pressed to work the deuce hard enough to overheat it if everything is in working order. These are hearty trucks and won't leave you stranded without warning. They require no juice to run. Truth be known, I'm more comfortable on long trips in a deuce than in my Chevy pickup. They're just that dependable.

 

[cranetruck]

I think I have an extra take-off sending unit. I'll check it and mail it to you if you want me to, Kenny.

 

[emmado22]

The sending unit is where that wire plugs into on the 1st picture.. Hopefully yours didnt "weld" itself to the manifold. Brass and Aluminum dont play well togther.

 

[sermis]

My truck was getting hot, 240 on a 100 degree day. Pucked out fluid. Had to get the radiator rodded / cleaned. He said it was 2/3's clogged. Now on a hot day running hard with the 46" tires it will go to 200 and stay there. Also the fan was reversed. When I pulled the M944A1 home Monday the temp never got over 190 - 195. Max speed was 30mph and she was pulling very hard in low range all the way.

 

[kendelrio]

When I was hauling a F-800 up from Matthews, La (about 200 miles, load was 18k+) the temp never went above 180. Good luck (In fact, I have a pic of the guage under load... will find and post)

 

[Ronbo]

nott to change the subject , But what in the 2 pictures posted , what is the sensor to the left of the blue hose in teh first picture? Thanks

 

[Ferroequinologist]

My truck just started doing this yesterday, the temp was fine on the way up to VA, then it started to creep up, very slow. it got to 240 and I pulled over. The upper part of the radiator is hot like it should be, and the bottom was cooler. I figured it was the thermostat sticking. Took it out, but the temp started creeping up again. Sensor? I don't think its the water pump, coolant is flowing well. (especially well with no thermostat.)

 

[Jake0147]

The sending unit is where that wire plugs into on the 1st picture.. Hopefully yours didnt "weld" itself to the manifold. Brass and Aluminum dont play well togther.

I've had suprisingly good results, first with the pipe plugs, second with that sending unit, by "cracking" them when the engine is fully up to temperature. Warm it up, crack them open until you just see the first drip of coolant, then STOP TURNING, come back when it's cool and go about whatever it is you are fixing.
Maybe just lucky, but it's worth a shot...

My truck just started doing this yesterday, the temp was fine on the way up to VA, then it started to creep up, very slow. it got to 240 and I pulled over. The upper part of the radiator is hot like it should be, and the bottom was cooler. I figured it was the thermostat sticking. Took it out, but the temp started creeping up again. Sensor? I don't think its the water pump, coolant is flowing well. (especially well with no thermostat.)

I thought I had a stuck thermostat for similar reasons. Seemed to like 190 (verified separately from the dash gauge). After several "informal tests" I determined that it's opening fine. Early actually. Further investigation found enough sediment in the bottom of the radiator to block two thirds of the lower hose bung on the radiator. Coolant looked fine until after I disturbed that sediment.

 

[THEROAD]

I never leave home without an IR temperature gun. Great for checking on lots of things. The HF ones are crap at lower temps. +- 6 degrees at room temp. That is not a big deal at 200 or so.

 

[vtdeucedriver]

I've had suprisingly good results, first with the pipe plugs, second with that sending unit, by "cracking" them when the engine is fully up to temperature. Warm it up, crack them open until you just see the first drip of coolant, then STOP TURNING, come back when it's cool and go about whatever it is you are fixing.
Maybe just lucky, but it's worth a shot...



I thought I had a stuck thermostat for similar reasons. Seemed to like 190 (verified separately from the dash gauge). After several "informal tests" I determined that it's opening fine. Early actually. Further investigation found enough sediment in the bottom of the radiator to block two thirds of the lower hose bung on the radiator. Coolant looked fine until after I disturbed that sediment.

Dam, you OVH that truck????? Glad one of my girls went to a good home.

 

[Jake0147]

Dam, you OVH that truck?????

Not yet for sure but I'm working on it. I figure at the rate I'm going, by the time I get to that point, there'll be another twenty years of sediment in the radiator and I'll have to start all over again.

 

[Wildchild467]

i know its an old thread, but i was looking in i think the LDS troubleshooting manual and the LDS engines have a thermostat that opens at 160 degrees instead of the regular 180. what makes the LDS more special? could the cooler temps mean more power better for more dense air, cooler piston temps and allow to feed it more fuel?

 

[pjvargas]

Overheating

I would definitely be concerned. Tech manual operating procedures says normal operation temp gauge should be 180-200 degrees F, and to stop engine immediately if engine temp rises sharply to 210 degrees F or more or stays below 180 degrees F.
Mine was having the tendency to climb to 210 and then to drop back down if I kept the wind flowing over the front end, so I am in the process of replacing the water pump, thermostat, fan blade, and radiator (just cause I hate getting stuck in odd places at the worst times). A lot of work but it didn't look like the truck had gotten a lot of attention in this area from the military. The 180 degree thermostat and seal I got from NAPA, the water pump and radiator are NOS (also replaced the associated hoses and belts for the alternator and water pump/compressor at the same time).

 

[Westech]

All the multi fuel T stats start to open at 160 and fully open at 185.

 

[Jimma]

One of mine runs at 180 consistantly and the other about 170 consistantly. They have only gone over that when operating under a heavy load in real hot conditions. However, they never went about 195.

 

[rawfish]

Wow, glad I found this thread. Bought my M35 last night and drove it 30 miles home. Temp gauge was up to 220. Everything ran fine and no gushing of fluids. I wonder if the sending unit is bad. I twas also cool last night around 45*