Mark I'm going to take the truck out today and hopefully that will be the issue. Now that I think of it, the high temps came on when I pushed the Thrift Air off on the way to town. Here's hoping. Tramp
Tramp Wish you could use a big bolt radiator,my 51 6400 runs cool at 185 degrees even in this 95 degree heat. just use 50/50 in it. Even in a slow moving parade,in the cold my round heater core wants to seep but I hate to gunk it up with stop leak. So may have to bight the bullet and buy a core from Carter's
An old timer once suggested to me to drill an 1/8 inch hole in the thermostat to keep air lock from happening in the block. In no way am I suggesting this will fix your issue.......
Last edited by ascwrangler1; Mon Jan 09 2023 01:54 AM. Reason: add photo
Have you tried a different therm. It seems like half the therm. I used to get were defective. Like Wrangler says itsa good idea to drill a small hole in it. I can't imagine why you need a bypass. I have worked on cars & trucks with SBC engines for many years & never had an external bypass. The aluminum radiator from Champion is a good idea.
George
They say money can't buy happiness. It can buy old Chevy trucks though. Same thing.
I've never seen a small block with an extra bypass hose, just circulates through the heater. The big blocks had the bypass hose, so did my 6.5 Detroit Diesel.
1957 Chevrolet 5700 LCF 283 SM420 single speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto, 1978 Yamaha DT175, 1999 Harley Davidson Softail Fat Boy
I've never seen a small block with an extra bypass hose, just circulates through the heater.
Here's one.
I had the same problem on my small block with the vortec heads until I added the bypass. I couldn't use the little 90 degree hose and fittings because I already had plumbed the heater into the top of the water pump. The problem has to do with the iron vortec heads that were used on late 90's trucks that requires the bypass. Some used the heater coolant circulation for the bypass because the heater control valve bypassed back to the water pump when the heater coolant flow was closed off.
I think Tramp did his happy dance when he fixed the problem.
I had only one Vortec small block, that was a '98 4.3 in a half ton, all stock, so I'm not qualified on them. Prior to that were all '70's and '80's 350's and 454's. I tend to keep things as stock as possible and have not had overheating issues so the bypass mod was not in my sights. With my '57 283, I added an overflow bottle so I can keep the cooling system free of air, it does what I want.
1957 Chevrolet 5700 LCF 283 SM420 single speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto, 1978 Yamaha DT175, 1999 Harley Davidson Softail Fat Boy
