Thoughts on running hot.

[Steve Turner]

1991 idi 5 speed. New belts. Coolant full and clean. Truck runs out great temp 1/4 of the way up most of the time. When pulling up thru the mountains with vehicle on back it wants to creep up to 3/4. Soon as I level out it drops back down. Usually can pull in 4th under 2000 rpm. What is your thoughts? Clutch fan seems to be working.

 

[HS108]

Its gonna get warm pulling, just using the dummy gauge is gonna be tough to tell what real temps are.

As long as you arent over heating it you should be fine. I ran mine pretty good in the hills of PA, got up to the M and A, but went down after, Truck still runs solid

 

[IDIBRONCO]

Remember that the factory gauges are next to worthless. They don't tell you anything accurately. Now for some solid numbers. People on here say that you can run these engine at 220* all day long and be just fine. You can run them to 230* as well. 235* is fine for a short while too. The more important number is your EGTs. Since you didn't mention them, I assume that you don't have a pyro to keep an eye on them. A pyro is more important on a N/A engine than on one with a turbo. The turbo will push more air through the engine to burn all of the fuel that your IP is putting to your injectors. This is what keeps the EGTs down. A pyro is more important that a manual coolant temperature gauge.

 

[Oledirtypearl86]

@IDIBRONCO I'd spot on the factor gauge on my 86 will pegg solid on the l at like 230 so it helps but it's normal to warm up pulling a long grade also check your radiator for some scale build up or your water pump might be getting ready to **** the bed

 

[cozinsky]

Mine does the same thing. I have a mechanical gauge hooked up and it will run all day long at 195-200 on flat roads with no hills. Pulling a trailer up a long grade I have to keep a close eye on it though because it will heat up quickly. I've had it at 230 many times but as soon as I get back on flat roads it drops back down.

 

[Cubey]

Mine does the same thing. I have a mechanical gauge hooked up and it will run all day long at 195-200 on flat roads with no hills. Pulling a trailer up a long grade I have to keep a close eye on it though because it will heat up quickly. I've had it at 230 many times but as soon as I get back on flat roads it drops back down.

My RV ran 190-200+ on flat highways until I got a new fan clutch (and new thermostat). Now it runs about 180-185. It's probably comparable to towing 5k-7k since it's so tall and 4k+ heavier than a truck.