Hello,I have been trying to get to an optimal (lower) engine temperature and would appreciate your advice.

I have a '66 Mustang289 convertiblewith automatic transmission and an after-market A/C. The car was rebuilt about two years ago and now has a 302. I have been having concerns that the car is overheating. On cool days, the car is running between 160 and 180. The problems start when I am in stop and go traffic, or driving in 90+ degree weather (at any speeds). In those cases, the car temp can get as high as between 210 and 220 I have a gauge that measures directly to the engine. The engine may even go higher if I don't drive gingerly or keep the A/C off; I don't know. I am concerned about overheating. I have seen conflicting information about the appropriate temperature range and was wondering whether I should be concerned. How hot is too hot for this car?

Next, what can I do to get the temp down? I keep the A/C off, which sucks on hot days. I also keep the speed below 60 mph when it is really hot outside. That helps but isn't a permanent solution. The cooling system has been flushed. The water pump and thermostat have been replaced. I replaced the fan with a five-bladed fan and added a fan shroud.I even put in a 2-core rad. Coolant mix is 50/50. Any thoughts on what else I can do?

I appreciate your help and ideas.

 

180 is too cold, and 160 is way too cold for optimal combustion. You're getting so much quench at that point that i bet you're losing at least 15% efficiency. Most of these engines were originally equipped with 192/195 t-stats for a reason. Basically, you want the engine to run as hot as it can without causing any damage. 195-210 is pretty good operating temp. 220 is getting up there, though, I wouldn't want it to creep any higher than that.

First off, you need to get yourself a good three row radiator. The factory two-row radiators were barely adequate in the first place. While you've got the coolant drained, drop in a high-flow 195* t-stat. I've been using a Mr Gasket unit for years and I'm very happy with it.

When you fill up the coolant, use a bottle of Water Wetter. This will help eliminate any boiling hot spots in the engine. You may even move to a 40/60 coolant/water mix to aid cooling.

I bet between these three things, you fix your problem

 

Yep, gotta love these old Ford engines, they like it hot.

 

Thanks, Starfury! I am going to look into all three of those options. I can keep it under 220 most of the time but was getting a little concerned, especially as the hotter months approach.

 

If you live in a temp sensetive area look into getting a tranny cooler too. There's space to mount it in front of your radiator, and you will never burn AT fluid again. For less than $50 you will save an early rebuild. I think all modern cars have AT oil coolers now as stock equip.

Carlos