Taking the family on a road trip from Dallas to Pensacola. Up to 96F outside, Air-conditioning is on, lot of luggage, 4 people and the temperatures get up to 221F before I turn the AC off and it settles to somewhere around 210F ( measured via UG).

I have a 5 year old Nissens radiator & water pump (The one with the brass impeller), in-line 185F t-stat mod, and 3300 CFM Electric fan which turns on at 185F. Didn’t have this problem for the last 5 years unless we were climbing a steep long hill, but outside temperatures never rose above mid 80s.

Bottom line, this thing’s supposed to be able to tow nearly 8000 pounds, so I’m certainly not putting more strain Than was designed. Suggestions?

 

Coolant level ? Did it drop at all ?
Tstat going bad ?
Wash your rad maybe it’s dirty

 

Coolant level stays full.
I can remove the thermostat and see if that fixes the problem. Good suggestion.

 

Remove the grille. These trucks don't have excess cooling capacity. The safari grill was an attempt to accomodate the temps you are talking about. You can remove the grille pretty easily and it will improve airflow a little. Also, make sure you have the AC set to recirculate (heating outside air requires more energy). Pull the hood sealing strips near the windshield, that should allow some hot air to escape out of the engine compartment and increase airflow across the radiator.

 

7700LB in 4Lo, how fast were you going? 65MPH & slower with a 180F and a good cooling system = 188-195F. 65MPH & up = 195F-206F and under load fully loaded it could go as high as 215F. Key is the temp went down from 221F to 210F so that shows the cooling system is working. Once you get past the happy medium where the radiator is keeping up with the heat being produced temps will rise. Grill openings are small, radiator isn’t that big, and make absolutely sure your aux efan for the AC is working or it will put stress on the cooling system when the HVAC is on and the efan is INOP.

 

If he had 4lo engaged that wouid make engine run harder right ?
Doubt he was crushing on 4 lo

 

If he was in 4Lo he’d be running higher RPM’s and it would be running at 188F all day long if the RPM’s were in the 2,200RPM to 2,500RPM range. The clutch fan would be fully engaged & pulling air like crazy. I’m certain he was in 4Hi just cruising along, but in 4Hi I think it’s around 5,500LB that you can tow.

 

Speeds went up to 84 mph. I also have a 13,000 pound winch blocking some of the grille which is a new addition and may factor in. I will test the auxiliary fan operation and implement some of the other things mentioned above like removing the hood sealer.

Anyone got a read on a better radiator in case that is necessary?

 

You have the in line mode with a 185 thermo. Try a 180

 

A 180° thermostat won't help, unless the 185° thermostat isn't working as it should. Once the thermostat is fully open, cooling at highway speed depends primarily on the efficiency of the radiator, and secondarily on the efficiency of the water pump. The fan and fan clutch should affect cooling system performance only when the truck is stopped or moving slowly in traffic.

That said, if the thermostat is not opening as it should temps will be high. My money's on a failed thermostat.