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!973 Chevy Sportscoach 455. Runs good but appears to overheat (heat gage will go all the way up, actual temp unavailable) when driving over 55 miles per hr., uphill or headwind. Ambient temperture has little effect. Runs cool when off the gas and or downhill. Does not overheat in city driving. Replaced thermostat & fan clutch fixed to stay locked on.
!973 Chevy Sportscoach 455. Runs good but appears to overheat (heat gage will go all the way up, actual temp unavailable) when driving over 55 miles per hr., uphill or headwind. Ambient temperture has little effect. Runs cool when off the gas and or downhill. Does not overheat in city driving. Replaced thermostat & fan clutch fixed to stay locked on.
I would check to see if the bottom hose is collapsing under high engine speeds. First try to squeeze the bottom hose to see if it has a spring inside or has enough wall thickness to prevent collapsing.
Perhaps the thermostat isn't opening all the way. New ones are cheap. How old and how clogged is the radiator? Some radiator cleaning could help. That is cheap and easy, too.
Boy, that fan must really roar. Even a good clutch slips 10 to 20 percent.
I am having the same problem. I just put a water pump, new hoses, new belts, I have a temperture clutch fan and it is coming on.I also have a elect. fan and I grounded it out so it stays on. It will not run hot at 55 MPH.I am going to change the thermostate tomorrow I also cheched the timing.
I do remember a new 427 in a 49 chevy overheating. The heater hoses were the culprit. I can't remember if they were crossed or what but any info that might help someone out of a headache is cool with me.
Also having problems with over heating. In last 2 weeks I have got as far as 150 miles from home and my 1985 Mallard Chevy 454 has over heated. Hve replaced fan belts, alternator, hoses, and checked the water pump. We think we have came up with the problem and that is head gaskets that seal sometimes and not other times. The reason I say this is because some times the engine skips and has a small amount of water on the plugs other times it runs great. I have gone 3 miles and had it over heat and have gome up to 150 miles before it did. I hope this helps.
Also having problems with over heating. In last 2 weeks I have got as far as 150 miles from home and my 1985 Mallard Chevy 454 has over heated. Hve replaced fan belts, alternator, hoses, and checked the water pump. We think we have came up with the problem and that is head gaskets that seal sometimes and not other times. The reason I say this is because some times the engine skips and has a small amount of water on the plugs other times it runs great. I have gone 3 miles and had it over heat and have gome up to 150 miles before it did. I hope this helps.
Also having problems with over heating. In last 2 weeks I have got as far as 150 miles from home and my 1985 Mallard Chevy 454 has over heated. Hve replaced fan belts, alternator, hoses, and checked the water pump. We think we have came up with the problem and that is head gaskets that seal sometimes and not other times. The reason I say this is because some times the engine skips and has a small amount of water on the plugs other times it runs great. I have gone 3 miles and had it over heat and have gome up to 150 miles before it did. I hope this helps.
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