New (used) IH 7500 Dump Truck purchase, modification & fix up

[Hay Dude]

don't worry about the fan cycle. School buses, cycled literally non stop their entire life, and we never had failures.

I’m beginning to think it’s an IH software thing.
Not as worried about the fan cycling as I am the reason for the fan cycling, and that is these swings in engine temps.

I’ve never owned a diesel where the temp continually rises, then is cooled by the fan. Everything else I have owned climbs to operating temp, then sits there. Fan does not come on unless hard work.

This one comes on empty or loaded all the time.

 

[LittleBill21]

I’m beginning to think it’s an IH software thing.
Not as worried about the fan cycling as I am the reason for the fan cycling, and that is these swings in engine temps.

I’ve never owned a diesel where the temp continually rises, then is cooled by the fan. Everything else I have owned climbs to operating temp, then sits there. Fan does not come on unless hard work.

This one comes on empty or loaded all the time.

water pump checked? hoses checked? thermal camera shot at the radiator to confirm no blockages? can be a lot of things.

 

[Hay Dude]

water pump checked? hoses checked? thermal camera shot at the radiator to confirm no blockages? can be a lot of things.

Yep. I know.
Even changed out rad fluid.
I will check everything again, but I think we checked everything off the list.

 

[mrmikey]

Related: I think the fan in my truck may be air powered, I will check.

Air powered or air clutch? Is there such a thing as an air powered fan?

 

[Hay Dude]

Air clutch. Not positive, need to go back & check.

 

[sandman2234]

I drove a Volvo way back in 1980 for a few trips, and it did the same thing with the cooling down and heating back up. Didn't drive it long enough to know what caused it, but it also affected the heater, which was kind of needed back in that winter.
It also told me that I needed to quit burning the candle at both ends, because running the heater as low as it would go, was still making me sleepy but when i stopped to grab a quick nap, the darn thing would cycle down and no heat. Too cold to sleep, so I would push on.
David from jax

 

[D&D]

Yep. I know.
Even changed out rad fluid.
I will check everything again, but I think we checked everything off the list.

Pressure test on engine and rad cap? EGR valve and cooler?

 

[redman135]

Hay Dude, I suggest you double check that you have the correct thermostat for that SPECIFIC engine. (post on p 51) Many years ago I recall a fleet had head troubles. The problem was tracked back to the thermstat. I don't recall the details.

 

[Hay Dude]

Will do and thanks for the suggestions. I really like the truck, but dislike the rise in temps and fan cycling.

 

[Hay Dude]

Pressure test on engine and rad cap?

Done

EGR valve and cooler?

EGR valve & cooler was replaced it was gunked up pretty bad.