I have been working on my 66 Mustang for about a year. I have replaced the two row radiator with a three row, all new hoses, new 160 thermostat. The car still shows overheating on the gauge. I have used a temperature sensor at the block and it read 220 degrees. At the thermostat about 180 and the radiator about 170.The sensor goes over 1/2 way but the unit does not boil over. Seems to have good water flow but I can not see all of the radiator. I am concerned the 220 in the block will cause gasket trouble etc. Have spoken to two different shops one said I have a bad gasket or head leakage, but no normal signs of that any suggestions on what to look for

What cooling fan are you using? Is it electrical, fixed flex-fan, or with a fan clutch? Either way, there’s not enough air coming across the radiator to cool the coolant properly. The thermostat is totally open with the scenario you’ve given, and the coolant is moving too fast through the radiator to get cool. The 160 deg. thermostat may be too cool for this engine. What engine are you running in that Stang?

It’s the stock fixed fan blade. There is no shroud on the radiator since it didn’t seem to come with one. checked parts book could not find out if it was standard. Running a stock 289/ 2bbl with three speed automatic. Bought car from original owner and it only has 51k on the engine. checked timing to see if it was advanced (nope, when I had a 180 degree it really ran hot. Did a lot of rebuild to this car and it is the one point I can’t fix. Got three of these and it is the only one giving me a problem.

You need a fan shroud. Many parts houses do not stock fan shrouds, I’ve found out. And they can be hard to find for classics, like yours. But, I found an aftermarket one at Mustangs Unlimited http://www.mustangsunlimited.com/itemdy00.asp?T1=DA230+01. This should fix your problem.

Try a compression test in case it is a leaking head gasket. 160 was a good idea but the colder temp can cause sludging once the engine is repaired.

One of the things I am going to try when the weather gets nice and I can get it out of the garage.

I"ll give it a try and see if I can find one. Sounds like you are into them also.