# Cooling Problems with my 67 GTO



## 67PLUMMIST (Sep 1, 2010)

I have a 1967 GTO with the standard 335 horse motor and a 4spd trans. The car runs hot on the Highway only. If I run at 35 to 40mph it is about 195. If I take it up over 50mph it runs from 210-215. It does not overheat but is sluggish at that temp. I have replaced the thermostat and run with no thermostat, no change. New water pump, Vacuum advance is working fine, have a fan shroud, new fan clutch, and a 4 core desert cooler radiator. The engine has good coolant flow. I want to get it to run under 200 on the highway. The only other idea is to get a high performance alum radiator. Does anyone think it is the radiator? Other suggestions?


----------



## 05GTO (Oct 6, 2004)

Here are a few suggestions, I corrected my overheating problem by using a Mr. Gasket fan spacer which moved the fan closer to the radiator.

http://www.gtoforum.com/f50/possible-causes-gtos-overheating-15588/


----------



## geeteeohguy (Feb 2, 2008)

Look carefully into the water pump divider plate clearance, water pump impellor (cast impellor mandatory), and water pump pulley diameter. There are mixed feelings on this, but it sounds like your fan is working properly. Faulty fan/fan clutch means high temps at low speeds. At freeway speeds, the fan doesn't matter much. You're getting a ram effect thru the radiator core just by going down the road. Your water pump could be turning too fast, causing the coolant to cavitate and causing loss of efficiency. A properly clearanced water pump driven at the right speed is a big help.


----------



## likethat (Oct 5, 2007)

Well let me tell you. I am ashamed at this but.... When I redid my 67 camaro 427 I took the fan apart to paint it and put it back on backwards. How did I find out.
The car was 165 degs up to 30 miles an hour. Once I was on the high way it would climb to 225. I couldn't figure it out. So I took out the thermostat completely and same thing 225 at 55+. 

So 1 day after some break in time on the engine. I was replacing the secondary spring on the Holly to let it come in faster and upped the timing a bit. Why I was timing it I looked at the fan and with my head low to the engine I thought to myself why am I not feeling a ton of wind right now. So I put my hand in front of the radiator behind the grill and well there was wind blowing throw. All the sudden I was like you dumbass you put the fan on backwards.
Turned the fan around on the clutch and 165 at 55+ on the highway. Doah!


----------



## geeteeohguy (Feb 2, 2008)

likethat, great story. Even after 30 years of working on these things, I always double and triple check this stuff. Very easy to screw up. I noticed that the big 19.5 inch Pontiac fan I bolted onto my '65 last month actually said "FRONT" on it! I was glad it did, too. Fans, clutch discs, head gaskets, etc......always good to make sure it's in there the "right" way!!


----------

