67mustang302

Sounds like a fan issue. How is it being controlled?

norcal_ryan1966

Fan had a side mounted thermostat with a probe in the top radiator hose to sense temp

Gun Jam

Im still curious if this is an old fan...as in yes it worked in the past. Or is it a new fan that never worked?

I have daily driven my 66 for the last 17 years its used an electric fan for that entire time. A flexalite black magic for about 15 years and a Derale fan with a Derale PWM control box currently installed. Both fans used probes. The only issue so far has been one relay for the blackmagic fan before it was replaced by the derale. I think either way a temp warning alarm (audible) is a good idea...Yeah okay you dont have a relay to fail but you've got a belt that has water pump plus extra fan load...bet that doesn't last 15 years. With that in mind I might not argue that an electric setup is more reliable...but in my case in my application I think its better and thats why I run it...The pwm setup is pretty wicked.

norcal_ryan1966

The electric fan is probably 7 years old. The electric fan worked when I had my car on the road 3 years ago. I've still kept everything so I can diagnose at a later date. I've been itching to get my car driving for so long, switching to a manual belt driven fan seemed like a cheap cost effective way to try and do that. I'll keep everyone posted. Drove 70 miles today in varying driving conditions.

creel228

I hate to jump on your post but I am having an issue sorta like yours. I have a 65 with a 289 pretty stock motor with the stock fan and no shroud. I built the motor several years ago and drive it on weekends around town and the stock temp gauge has hardly ever moved. This summer when the temperature was in the upper 90's I drove it to work one day and on the way home I noticed the gauge was up half way, first time I had ever seen it move but I figured as hot as it is outside that's why it was that high. Every time since when I drove the car I noticed the temp gauge coming up about half way but never past that. Last week it was nice and cool outside, in the 70's, so I took it to town. I made a stop at Walmart and after I left there I had to drop off some books at the Library. I left the car running at the Library and when I got back in the temp was way high so I tried getting the car up to speed to cool it off as quick as I could. Since I was in town I couldn't go real fast but it did cool back down closer to the halfway point and stayed there the whole way home. I have checked it since and I don't think the thermostat is stuck so I am thinking maybe my radiator needs flushing, what do you think? I don't want to put an under the dash gauge in the car because I want the inside to stay all stock. The radiator is about 8 years old, its a stock radiator. Do you think I just need a shroud or maybe a better fan? Oh yeah my thermostat is a 180 I believe.

norcal_ryan1966

I would hit the low lying fruit first. Tstat is cheap and simple, radiator shroud is cheap and simple. And a radiator flush/pressure test wouldn't hurt. All of those items are fairly economical and cheap.
What about putting an aftermarket gauge within your stock cluster? Or temporarily plumbing in a new temp gauge with the temp reading until the issue is resolved?
I ended up switching from the electric fan to a steel 15" race fan (believe it's a 6 blade) and a 3-1/2" radiator shroud. I could not believe the difference. Cruising around town my car runs at 170 - 180 max. Same thing, sometimes a bit cooler on the highway.

Let me know how it goes.