M925A2 Running Cold

[Steelreaper80]

My truck was running hot due to a bad thermostat. I ordered the correct part and picked it up directly from Cummins, changed the water pump, flushed the radiator and motor, and have the proper coolant and additive package. I also replaced the shutterstat. Both the shutterstat and thermostat are 195 degrees. Now my truck is running at 165 degrees at both idle and highway speed while loaded. I know it has gotten cold out and I am hoping that is the problem. I ordered a winter front for the truck and it will be here tomorrow. I have noticed it does heat up if I am going light to light in traffic a tad but once I get back up to speed, the temp drops back to 165. Is it just too much cold airflow on the radiator? The heater core is blowing warm air. Not hot, not cold. I have not had a spare moment to check with the IR temp gun yet but will as soon as I can. Any ideas?

 

[98G]

Like you, I suspect it's just due to cold ambient temps and lots of airflow.

 

[Steelreaper80]

Like you, I suspect it's just due to cold ambient temps and lots of airflow.

That is what I was thinking. I know diesels don't put a lot of heat into the coolant, they are designed to be run hard under load, and just, in my opinion, the radiator seems huge for a little 8.3 liter. Is it the same rad for the NHC-250?

 

[steelsoldiers]

That is what I was thinking. I know diesels don't put a lot of heat into the coolant, they are designed to be run hard under load, and just, in my opinion, the radiator seems huge for a little 8.3 liter. Is it the same rad for the NHC-250?

Is your fan clutch engaged all the time? The fan should spin freely on the hub with the engine off/cold. The clutch could be locked up or your new fan clutch solenoid could be faulty. If the clutch turns freely, then you could disconnect the air supply line to the clutch and start the engine cold to see if air is coming out of the supply line.

If everything is working normally and ambient temps are cold, it does take a while for those trucks to get up to normal operating temps. The 8.3 doesn’t make a lot of heat without a load on it.

The 8.3 and NHC-250 rads are interchangeable, but the lower bracket is not. I found that out the hard way on my M925A2 project.

 

[Steelreaper80]

Is your fan clutch engaged all the time? The fan should spin freely on the hub with the engine off/cold. The clutch could be locked up or your new fan clutch solenoid could be faulty. If the clutch turns freely, then you could disconnect the air supply line to the clutch and start the engine cold to see if air is coming out of the supply line.

If everything is working normally and ambient temps are cold, it does take a while for those trucks to get up to normal operating temps. The 8.3 doesn’t make a lot of heat without a load on it.

The 8.3 and NHC-250 rads are interchangeable, but the lower bracket is not. I found that out the hard way on my M925A2 project.

New fan clutch. Not spinning until 195 degrees. Truck is under load pulling an M322 trailer and 15,000 lb skid steer with 3,000 lbs in the bed. Everything is working as it should. I am hoping it is just the cold.

 

[simp5782]

New fan clutch. Not spinning until 195 degrees. Truck is under load pulling an M322 trailer and 15,000 lb skid steer with 3,000 lbs in the bed. Everything is working as it should. I am hoping it is just the cold.

Did up verify temp with infrared gun or just trusting the gauge?

You may have to go to the 205 thermostat and shutterstat

 

[Steelreaper80]

Did up verify temp with infrared gun or just trusting the gauge?

You may have to go to the 205 thermostat and shutterstat

Not yet. I will in the morning once I pick up the skid steer with forestry head again. I will put it back under load and check everything once I get to the field.

 

[Steelreaper80]

Well with warmer temps today, it idled up to 195 and lowered a bit going down the road down to 175ish. Light to light it ran at normal temps. I would say everything is fine, I guess it will just be time for the winterfront.

 

[Jbulach]

I’m thinking your new thermostat has issues.