Bought a 91 Ram ,318 ci, with 42,000 original miles two years ago. Up to 50,000 now. Went from a 2 tube to a 3 tube radiator (new), removed fan and clutch and went electric, added a trans cooler, new water pump, themostat, flushed twice, new muffler and tail pipe & added a set of guages to better monitor things. The problem is it still runs on the warm side (225 - 230F) at interstate speeds. Around town and speeds up to 60 mph the temp is 200 to 210. Get on the interstate and the faster you go the hotter it gets. Get the speed down and the temp drops.

I drove from southeast Louisiana to the coast of South Carolina this past spring. It didn't start this until the last 100 to 150 miles going over.

Any thoughts out there.

I thinking of doing a chemical flush and or going to a 160 degree thermostat. I'm running out of ideas.

Thanks,
Paul []

 

Has it done this since you put the electric fan in? sounds to me as though the electric fan isn't pulling enough cfm at higher speeds of course the higher the rpm the more heat.

 

It was doing this before the modifications. I did this to correct the problem. At highway speeds the fans shouldn't be a factor. I have two 12" fans in front of the condensor pushing and two 12" on the back side of the radiator pulling. They are staggered to give air flow over the whole cooling system with overlap of some of the airflow.

I bought a small camper to pull. 2000 pounds. The funny thing is, it does it with or without the camper. It doesn't run any hotter with the camper.

 

Yeah the fans should not matter at speed. What tstat are you running now, 195 is oem iirc. I'm running a 180 in my 86, I've heard that 160 with fuel injection isn't good since you'll never get out of warm-up mode and it'll run rich. It sounds like maybe you got a bad t-stat. Higher speeds means more work, more heat, and if the stat isn't opening up enough it makes sense that it wouldn't cool as well.

I'd get a new 180, throw it in a pot and boil it with a thermometer to make sure it's opening properly at the right temp.