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Old 09-09-2017, 09:20 PM   #7
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Join Date: Jul 2007
Location: Toppenish, WA
Posts: 10,227
Re: 56 truck heater hose routing - overheating

Originally Posted by 1project2many View Post

A question for you: Are you filling the radiator right to the top? If you are then you have no room in the system for coolant expansion. This will cause coolant to be pushed out the overflow line no matter how well the cooling system works. The radiator should be filled to about 1 1/2" below the filler neck. Fill to the top works if you have a recovery bottle and a cap designed for a recovery system.
Right there is the reason a lot of guys new to AD or TF trucks or Old vehicles in general have problems. On a stock style tank on top radiator you absolutely have to leave that expansion room/

Usually the heater hose off the manifold runs to the fitting on the heater core that goes in at the top and the one going to the water pump goes to the one exiting at the bottom. Same setup as the radiator, Hot in at the top cooler out at the bottom.

Drilling the small hole in the body of the thermostat is to let any trapped air bleed out before the thermostat opens so it isn't trapped there. Too big a hole lets a bit too much coolant get by and slows the thermostat opening down. No need to know why I know that but you can assume that----- and be pretty correct.

When I was towing a lot in warm/hot weather I would take an old thermostat and remove the guts and just put the washer/shell back. That slowed the coolant down to just above the point where a wide open thermostat would let it flow. Not worth much in cold weather because the engine never warms up enough to get heat out of the heater but great in hot weather.
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My ongoing truck projects:
48 Chev 3100 that will run a 292 Six.
71 GMC 2500 that is getting a Cad 500 transplant.
77 C 30 dualie, 454, 4 speed with a 10 foot flatbed and hoist. It does the heavy work and hauls the projects around.
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