Overheating on Freeway
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
I've seen early C3s and C2s driven on the highway with no fan at all. One was on an NCRS road tour where the repro fan clutch disassembled itself 50 miles from nowhere. Luckily the fan didn't penetrate the radiator. We removed the debris and carried on. Another car went ahead of us and found a generic make-do clutch ***'y. We installed it on the strickn car just outside of town on the side of the interstate.
Maybe later C3s are different but it would require that the clutch be at least partially engaged at all times to actually do any work.
Maybe later C3s are different but it would require that the clutch be at least partially engaged at all times to actually do any work.
When those fans are not running not only are they not providing any air flow they are likely restricting it somewhat. I can drive any distance on a day up to 80* at 55 mph or faster and the fans will not even turn on.
So the fan(s) are not needed for cooling at highway speeds under many conditions. Once it gets hot enough or I work the engine hard enough then the fans assist in the cooling is needed.
Definetly when the a/c is running a fan assist is going to be needed.
Thread Starter
Intermediate
Joined: May 2014
Posts: 48
Likes: 1
Mine is a 77 that has an engine that produces around 370 hp or so. I have electric fans.
When those fans are not running not only are they not providing any air flow they are likely restricting it somewhat. I can drive any distance on a day up to 80* at 55 mph or faster and the fans will not even turn on.
So the fan(s) are not needed for cooling at highway speeds under many conditions. Once it gets hot enough or I work the engine hard enough then the fans assist in the cooling is needed.
Definetly when the a/c is running a fan assist is going to be needed.
When those fans are not running not only are they not providing any air flow they are likely restricting it somewhat. I can drive any distance on a day up to 80* at 55 mph or faster and the fans will not even turn on.
So the fan(s) are not needed for cooling at highway speeds under many conditions. Once it gets hot enough or I work the engine hard enough then the fans assist in the cooling is needed.
Definetly when the a/c is running a fan assist is going to be needed.
Advanced
Joined: Aug 2013
Posts: 53
Likes: 0
From: meas az
my 75 is doing the same thing as yours car only has 17k miles on it i replaced all belts and hoses and installed a new Dewitt's radiator new 180 t/stat fan clutch seems to be working fine . will run 220-230 at 75 mph get off the freeway and start cursing city streets and it will drop to 190 -195 i will check timing tonight. i can not see a fan clutch giving a over heating problem on the freeways only . but i have been wrong before
Thread Starter
Intermediate
Joined: May 2014
Posts: 48
Likes: 1
my 75 is doing the same thing as yours car only has 17k miles on it i replaced all belts and hoses and installed a new Dewitt's radiator new 180 t/stat fan clutch seems to be working fine . will run 220-230 at 75 mph get off the freeway and start cursing city streets and it will drop to 190 -195 i will check timing tonight. i can not see a fan clutch giving a over heating problem on the freeways only . but i have been wrong before
Advanced
Joined: Aug 2013
Posts: 53
Likes: 0
From: meas az
well . like i said i have been wrong before drove to work and back in phoenix 107 outside today after resetting timing and still running hot {215/220} on freeway. on the way home i thought to my self what the heck everything else is new why not try a fan clutch . went to Napa and picked one up went home and changed it and went for a 40 mile freeway ride and never got over 200 at 75 mph . i would not believe it if i did not see it lost 15 to 20 deg on freeway with a new fan clutch thanks for the post i solved my running hot issue . 
