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Overheating blues (chevy 454)


LawnSite Member
Truck --1990 chevy 3500 4x4 454 auto,,air if it matters. Just got a free uni-mount western 7'6" footer. Truck overheats like mad. Don't matter if the blade is an inch off the ground or all the way up. I changed the thermostat went to a 180* still no help. Do they sell a straight fan for this thing ?? i think the clutch fan stinks or do i have other probs ????


LawnSite Member
How did you get a plow for free!! Maybe you already checked these things but here goes anyway.... Does your truck have the shroud in place around the fan? Do you have a body lift? Your fan clutch may be bad. Is your coolant mixed at the proper ratio? Maybe even the new thrmostat isnt working properly. Im not sure just some ideas.



On a 10 yr old rig I'd be checking the radiator,, the clutch fan "might" be bad,, I had one that would not drive the fan to any real speed, I replaced it and the problem went away.


LawnSite Member
Philadelphia, PA
i'm still learning about 90's trucks, but on all my mid 80's i put 160 thermostats in, and all the other guys have good points also. 160 will help out more than a 180

SlimJim Z71

LawnSite Senior Member
On that year truck, there are a few possibilities.

1. Water pump. Have it checked to see if it's moving enough coolant.

2. I would definately recommend getting the cooling system flushed. This is one thing that most people don't do.

3. Check the radiator. I have seen a few cars/trucks with SOOO many bugs and crap on the front side of the radiator, it was amazing the thing would even run without overheating.

4. Thermostat. I know you put a 180 in, but try a 160.

Just my $0.02



LawnSite Bronze Member
do you have a snow deflector on the plow, if not get one. Does it over heat at idle or when plowing. Or just when driving around with the plow on?


LawnSite Member
try disconnecting the fan clutch thermostatic spring coil
and rotate that coil so that the fan clutch is allways


LawnSite Member
When I had my towing service, my 85 454 had a lot of problems with overheating. When I finally decided I had enough of it, these are the steps I took to correct it , now Im not sure which one worked , or if it was all of them combined but when I was done my motor never got over 200 degrees and the truck was warm in the winter , no matter what I was towing.

Fan shroud - very important on a GM big block in a work truck.

Aluminum flex fan(clutchless) 5 or 7 blade fan if available

Electric cooling fan- now mine ran all the time when the key was on , but my partners wrecker was hooked up to a toggle and he used his only when the motor got warm

Trans cooler- less hot you have coming into the rad , less heat rad has to disperse.

4 CORE Rad- a little expensive but if the truck is your money maker, its well worth the extra cash outlay



LawnSite Fanatic

I have the exact same truck, and to be honest it is a hot runner. They just didn't have the cooling capacity then. I think they re-engineered the cooling system later in the 90's. Things that I have done... 180 t-stat, dont go 160, not enough heat, and overheats QUICKER! I rewired my aux. electric fan to a remote switch. OEM fan relay engaged when it was already overheating, 230 or so, too late! I had a bigger core radiator with bigger fins installed. Also, I added an external trans cooler (Big one). From the factory all it had was a rad tank trans cooler!! THAT WAS IT!! My truck has HD towing package and snow plow package too! Crazy, maybe they forgot to put an external one on. Anyway, don't get rid of the clutch fan/stock 7 blade fan. They pull more air than any flex or electric anyday. Check that the clutch is engageing properly. they engage at 195 deg. or so stock. I think GM should have used the diesel radiator and holes in the bumper on the 454's as well to help cool it down.

Good luck and keep that plow low and angled!