K20 getting hot when in 4Lo/slow

[5akman]

I have an '84 K20 with less than 10k on new everything: crate engine/700R4/transfer case/diffs etc. When running in 4lo it gets really hot on the gauge (220+) and the engine compartment is blazin' hot. This truck is a work truck in Alaska, primarily used on the beach hauling totes of fish from the beach to the local processing plant (10 miles away via highway). I've tried different tstat temps and that doesn't seem to make a difference. I am running headers and have a set of stock iron manifolds to put on next, hoping that will help. At freeway temps, everything is fine, its just low and slow on the beach that has me concerned.

Any other suggestions for larger radiator, fan size, etc? I think the engine is fine but I worry about the temp of the trans fluid when its running this hot.

 

[Dutch Rutter]

I have an '84 K20 with less than 10k on new everything: crate engine/700R4/transfer case/diffs etc. When running in 4lo it gets really hot on the gauge (220+) and the engine compartment is blazin' hot. This truck is a work truck in Alaska, primarily used on the beach hauling totes of fish from the beach to the local processing plant (10 miles away via highway). I've tried different tstat temps and that doesn't seem to make a difference. I am running headers and have a set of stock iron manifolds to put on next, hoping that will help. At freeway temps, everything is fine, its just low and slow on the beach that has me concerned.

Any other suggestions for larger radiator, fan size, etc? I think the engine is fine but I worry about the temp of the trans fluid when its running this hot.

The trans temp is probably fine in those low of gears. Without a temp gauge on it we can't really tell how its actually doing though. If the engine is showing those 220+ temps at low speeds I'd start by looking over my fan. Do you have a clutch fan and shroud? What size of radiator do you have? 4 core hopefully. And have you verified its all flowing correctly?

 

[5akman]

Its all new (less than 10k) including radiator, pump, hoses, fan clutch. Its a 4 core with shroud. I'll have to look everything over again this year and shoot some temps in various places with the Harbor Freight temp gun. I'll put a trans temp gauge on it also.

 

[dvdswan]

Is the water flowing in the radiator? Do the hoses feel hot to touch? Both of them? Heater hoses? Did you get a serpentine water pump or a v-belt water pump? They spin in different directions.

 

[Bextreme04]

Pics help. What does the setup actually look like? Just because parts are new, doesn't mean they are good. It sounds to me like a failed fan clutch.

 

[Corvette Ed]

On top of the good advice above,try blowing out the rad.from the fan side,check the thermostat and the fan clutch.

 

[RecklessWOT]

Wait, you said you're going 10 miles on the highway in 4 low? That could be your problem right there, might just be revving it way too high, try 4 high when you are getting up to highway speed. If I read incorrectly or misunderstood, sorry maybe I just didn;t understand the question

 

[5akman]

Sorry for the confusion, no, a mile or two on the beach in 4lo then 2H on the highway. I'm in CA now and the truck in is AK. I'll be back up over Easter vacation and will check out a few of the ideas mentioned in this thread.

 

[5akman]

Its a V belt pump

 

[Bextreme04]

Sorry for the confusion, no, a mile or two on the beach in 4lo then 2H on the highway. I'm in CA now and the truck in is AK. I'll be back up over Easter vacation and will check out a few of the ideas mentioned in this thread.

I would recommend you check and make sure the fan is all the way in the shroud, shroud is properly mounted, and that the fan has some resistance to turning(should be able to turn it barely with your hand with engine off). If the fan spins with no resistance, you have a bad fan clutch. If you can't hear the fan blowing hard when the temps are high, you have a bad fan clutch.