1966 289 Mustang Overheating

Bob B.

Member
Sep 10, 2019
5
1
13
43
Bella Vista, AR
My first time to post so please excuse me if I do something stupid. I have a 1966 Mustang. 289 engine. I recently replaced radiator and fan with a three core aluminum radiator and electric fan. Electric fan is set to approximately 180deg F. During the upgrade I also replaced the thermostat (also 180deg F). However, the temperature keeps rising past 180degs. Any suggestions on what can be causing my overheating problems? Anything else I can check? Electric fan is turning on at approximately 180deg. I used a heat gun to measure.
 
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2Blue2

I partied with that dude!, um girl, um whatever...
Mar 5, 2019
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Oahu
Start with the basics,
Compression test to make sure head gasket is not compromised.
Timing set right
Distributer functioning correctly
Vacuum leaks
Lower Radiator hose that is not soft and collapsing.

Get a tefba radiator filter to protect that new radiator, old blocks scale off rust, lots of rust.
Worth the 75$ IMO


th-23.jpeg
 

Bob B.

Member
Sep 10, 2019
5
1
13
43
Bella Vista, AR
I had the timing adjusted by someone that actually knows what they are doing (ie not me) because I initially thought it was maybe out of time. I did add a new (cheap) carburetor recently but I can’t find any more vacuum ports. I don’t know about the compression issue or if I got all of the air out of the system (I know it’s two separate issues). I did see a YouTube video of a guy drilling a small hole in the side of the thermostat to make certain the air was out of the system. I will look into bit issues.
 

Bob B.

Member
Sep 10, 2019
5
1
13
43
Bella Vista, AR
Thank you both so much for your suggestions. I like working on my car but sometimes I hit a dead end and it’s awesome to have some folks to throw out new out ideas.
 

Olivethefet

Slap me as well as point and laugh
May 17, 2018
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Enterprise AL
I dont anything about drilling a hole in the thermostat housing to let air out. That seems like a bad idea as then you would have a hole in the thermostat housing.

The way I burped the air out of the system in my car the last time I had to do it was as follows.

Fill the system up as much as possible.
Start the car.
Take the radiator cap off.
Let the car warm up while watching the level in the radiator.
As the engine warms up the thermostat will open and let air out of the block.
Keep topping the system off until air quits coming out.
This can take 20 or more minutes to do.

It worked for me.