Overheating challenges when towing

[VMacKenzie]

A friend at church has a '92 auto which runs great as long as it's not towing too much weight up a grade, which causes serious overheating issues.

He has replaced the T-stat more than once (Cummins T-stats), flushed the system, and pulled the radiator and had a mod done to move the inlet & outlet for better cross-radiator coolant flow (he said it's a common mod on 1st Gens, is this true?). When towing his 20' travel trailer (weighs in around 4500 lbs) up a grade such as Vantage Hill or Cabbage Hill he cannot make it more than about half to 3/4 of the way up without pegging the temp gauge and starts to boil over. He usually starts up the grade in 3rd gear but ends up having to drop to 2nd to try and keep from heating up too bad.

Also to note, usually runs the pyro around 1100 preturbo and trans temps usually top out around 215F. Any ideas?

Vaughn

[GO OVRIT]

Has the coolant ever gotten really dirty? He could have worn fins on the water pump. Could be a bad fan clutch.Is anything blocking the radiator?(grill gaurd, winch, etc...)

[PToombs]

Add an accessory trans cooler. His trans is getting hot and hotting up his coolant. This should help alot.
He could do away with the one on the side of the block at the same time. Unless he's where it gets really cold in the winter, then it helps warm the trans fluid. Kinda personal preference on that.

[VMacKenzie]

Thanks for your replies guys. Water pump is a good idea, I'll tell him to check that. I think he mentioned the fan comes on and roars but I'll ask him that.

PToombs that's a good thought, but I forgot to mention he already has an aux trans cooler. He said the engine heats up first, then the trans, so pretty sure it's not the transmission causing it.

Vaughn

[KTA]

A 92 Should have already had a crossflow radiator. I would be suspicious that the radiator is bad(full of deposits and you can't clean them out only replace) or a bad fan clutch. I had a fan clutch that worked but was weak and it made a big diffrence in temps. My trailer pulling truck is 300rwhp and about 900ft-lbs of torque and it will get hot at 23000lbs gross on a long grade. The cooling systems were only designed to handle 160hp continuous. I would say if the system is fully up to snuff probably 200rwhp is the most continuous power the cooling system can handle.

[VMacKenzie]

[quote="KTA"]A 92 Should have already had a crossflow radiator. I would be suspicious that the radiator is bad(full of deposits and you can't clean them out only replace) or a bad fan clutch. I had a fan clutch that worked but was weak and it made a big diffrence in temps. My trailer pulling truck is 300rwhp and about 900ft-lbs of torque and it will get hot at 23000lbs gross on a long grade. The cooling systems were only designed to handle 160hp continuous. I would say if the system is fully up to snuff probably 200rwhp is the most continuous power the cooling system can handle.[/quote]

Thanks KTA, he may have a '90 or '91. I'll suggest to him to replace the fan clutch, and if that doesn't work then swap in a newer radiator. He is not pulling that heavy of load, although Cabbage Hill is a bugger, but I know someone else with a '92 that pulled Cabbage with over 22,000 gross and while he did overheat, he made the hill without boiling over.