Hi I have 67 Coupe 289 that over heats on the Highway put not in the city.I have flushed the rad (2 core), new stat, hoses ,belts. There is a shroud and a 17 1/2 or 18 inch 7 blade clutch fan. pump look new from last motor re build.Think the fan and clutch may be wrong,I think it belongs to 24 inch Rad for 390 or 428 from what I found.Any ideas.

 

I'm running a 17 inch 6 blade mechanical fan on my 289, so that should be the correct size. Your clutch fan may not be working right at highway speeds. However, if I were you I would upgrade that old 2 row rad up to at least a 3 row. You might also consider an electric fan with an upgrade to the alternator if it continues to give you trouble.

 

well at highway speeds, it doesnt matter if you even have a fan or not. The speed your going is has plenty of air going thru the radiator. A fan isnt going to do anything going that fast, unless your revs are up. Its just there for the ride until you get into city speeds.

 

you bottom hose may be collapsing. If it is then you can either replace it or put a spring in there,

 

True dat!

 

Yup, that could be.. If you're temp is okay around town and only heats up on the highway, I would look at the bottom hose as was stated and also think about changing that two row to a three row... You also may want to think about a high flow water pump.

 

He is in canada so i think i may be able to get away with a 2 row for now. put a spring in the bottom hose.

 

where do I get a spring for the hose?

 

Canada or not, if he is overheating on the highway then he is overheating. He doesn't have enough cool water running through the block at fast enough rate. Two ways to help cure that is to increase the volume of water by adding a larger radiator, and to add a high volume pump to push more through.

 

lower hose collapse