on long trips at high speed (75) my temp will creep up to 230 (it might go higher but i haven't let it) but at idle it will drop down below 200. it dosen't seem logical , i don't know what temp thermostat i have in. when it starts going over 230 i slow down to about 50 and it will stats to creep down. kinda got me stumped, like the thermostat is in upside down

Weird! I agree should be the opposite. Is your belt slipping at high speeds and the water pump is not pushing water through? Just a guess. Mine heats up in stop and go traffic but runs fine at high speeds. It would be easy to put in a new 180 or 160 thermostat. I'd start there along with checking the belt.

Mark

Front spoiler, fan shroud and radiator seals are the most common cause of overheating at 'highway speeds'.

Garry, I have a 72 that has the same problem that yours has. Around town and in traffic it stays cool(under 200) but on the highway on a hot day it will creep up to 230. If I get over 65 mph it begins to creep up. On a cool night it doesn't do it. I have changed thermostats three times, ( have a 160 in it now, and that seems to do best) The only thing I haven't changed are the seals around the rad. By the way, the owner's manual that came with my car says 230 is normal operating temp. for it. Let me know if you find something that changes your problem.

I ran into this same problem while on the Hot Rod Power Tour this June in my '72. After looking at a couple of other '70 to '72 models, I noticed that my car (and one other) was missing a piece of foam between the top of the radiator and the top radiator support.

I stopped by an Ace hardware and made a "Bubba" fix to test...I bought a piece of foam pipe wrap that I could squeeze between the radiator and the support...then held it in place with tie wraps. The next day, while running in Louisian between New Orleans and Lake Charles, with the outside temps in the hi 80's low 90's, I was able to run 70+ with the A/C without any more problems with the temp rising.

Now, if I can just find time to get the right foam piece and replace the "Bubba" fix.

|UPDATED|7/20/2003 4:23:43 AM|/UPDATED|

I had the same problem on my '76. Replaced the fan clutch and saw a big improvement but it still runs hotter over 65 MPH. I think it is an inherent air-flow problem in C-3s

All the seals around the radiator contribute to a flow of air through the radiator. Unfortunatly, many radiator jobs are done without replacing these seals and with time even the ones that still survive do not do the job. I'd remove the radiator and replace all the seals including the upper as one guy suggested. All can be found from www.docrebuild.com, everyone should have this catalogue for all the little things that need to be replaced. Lastly, the fan clutch is designed to let the fan spin freely at certain speeds and if not working properly could contribute to the high temp. Also a new thermostadt and radiator coolant should be considered if you don't know how long since the last change.

Regards,

Gary,
I'm always hotter at highway speed than I am cruising around town. (45 minutes on the highway & I usually have the heat on to pull the needle away from touching the redzone.) Increased air-flow just doesn't seem to compensate for the added RPM's.

~ Joe

I live in the worse case scenario. Out here in the Arizona desert, we see outside air temps of 115 and above. I have driven my CE in this heat plenty of times, and my temps do the same thing that you are describing. I rarely get over 220, but that is in the normal operating range.

You don't have a problem, just don't let it get over about 230. Thats when the oil starts to break down.

isn't the speed limit there 65mph?
Sarge