Red River Refurb over heating...

[Hooper]

So I noticed the truck running warm a month ago. (ie 220) But I had it full of stuff and didn't think much about it. Then after using the truck to pull out a tractor I drove it around a country block and noticed it was almost to 240! I made an assumption that it had a bad thermostat. It seems to be just like your typical stuck thermostat. Before I tear it out this afternoon, I thought I better ask the experts if I may have missed something more common. It is a 1985 M923A1 Refurbished in 2010 with 70 hours on it. Full on coolant with a fresh oil change a few weeks ago.

 

[Swamp Donkey]

Did the fan ever come on?

 

[machinist75]

The air fan actuator on the front, top of the motor could have some bad orings. If you hear Sri coming out of it, it's bad.

 

[Scrounger]

First off if the truck was really running at 240 degrees you would have known it. Between the smell of things getting too hot and the knocking and banging it would have been obvious. Second the cooling system on these things make it pretty much impossible to load them enough to get them warm let alone overheat.
The first thing to do is see what the temperature is when it is running. Check the coolant reservoir with a thermometer and feel the top of the radiator and coolant hoses. The idea is to see if the coolant is flowing when the engine gets up to temperature. As already stated it may not get hot enough just idling and you may have to place some cardboard in front of the radiator.
The next thing to check is the temp sending unit, wire and gauge. If the gauge has a bad ground it will show a high temp. This could just be a simple matter of taking the gauge panel down and removing the temp gauge, cleaning everything up and reinstalling the gauge. If there is coolant flow I would go straight to the gauge next.

 

[Hooper]

Did the fan ever come on?

Fan kicks on way to early. It will be on after 5 minutes and stays on the entire time.

 

[Hooper]

The air fan actuator on the front, top of the motor could have some bad orings. If you hear Sri coming out of it, it's bad.

Fan motor sounds great, its just not cooling it down.

 

[Hooper]

First off if the truck was really running at 240 degrees you would have known it. Between the smell of things getting too hot and the knocking and banging it would have been obvious. Second the cooling system on these things make it pretty much impossible to load them enough to get them warm let alone overheat.
The first thing to do is see what the temperature is when it is running. Check the coolant reservoir with a thermometer and feel the top of the radiator and coolant hoses. The idea is to see if the coolant is flowing when the engine gets up to temperature. As already stated it may not get hot enough just idling and you may have to place some cardboard in front of the radiator.
The next thing to check is the temp sending unit, wire and gauge. If the gauge has a bad ground it will show a high temp. This could just be a simple matter of taking the gauge panel down and removing the temp gauge, cleaning everything up and reinstalling the gauge. If there is coolant flow I would go straight to the gauge next.

It is getting that hot. No noises but the power was starting fade so i shut it down.

 

[Gunzy]

I don't trust RRAD O/H'ed trucks. Saw one with less than 100 miles from O/H with a seized engine. I would open the drain valve of the rad and see if anything comes out and if it does is it red/rust colored. If it is you will need to flush the system or maybe even pull the rad for a flow test and boil/rod out as it could be plugged.

 

[Scrounger]

Losing power definitely can happen from overheating.
I’m guessing you don’t have a thermal heat gun to check for hot spots/ flow thru the radiator.
For the little effort and cost I would drain the coolant, remove the thermostat, replace the thermostat housing, refill then flush the system. After a good flush, drain and install a thermostat, I wouldn’t recommend running without one, the thing will never warm up. You could check the thermostat by the usual boiling method, however I would just replace it with a new one for peace of mind.

 

[Hooper]

Losing power definitely can happen from overheating.
I’m guessing you don’t have a thermal heat gun to check for hot spots/ flow thru the radiator.
For the little effort and cost I would drain the coolant, remove the thermostat, replace the thermostat housing, refill then flush the system. After a good flush, drain and install a thermostat, I wouldn’t recommend running without one, the thing with never warm up. You could check the thermostat by the usual boiling method, however I would just replace it with a new one for peace of mind.

Thanks, you might be on to something. Last night I had some extra time and thought I would idle the truck while cleaning one of the cars. It idled for an hour and finally got to 180 degrees. The right side of the radiator was hot but the left side was stone cold. Either the thermostat had not opened yet or the radiator is plugged. I have an extra thermostat so I think I will replace it as you said, why not.