77 Overheating

[Lil Red]

Have a 77 when I fill it with water and start it will push some water out the over flow as soon as you start it. Then after about 10-15 minutes will start to run hot this is at a idle. Any ideas whats wrong? Put in new thermostate. No bubbles in water. Pressure checked the cylinders all close on pressure.

 

[rrlund]

Sure sounds like a head gasket. Compression from one cylinder getting in to a water port somewhere.

 

[Dick W.]

That would be a no pressure system and will push some out at start up if it is too full. Is the radiator full of dirt in the tubes & fins? Is it clogged on the inside of the tubes? That's all I can think of right now.

 

[Lil Red]

The outside is clean. Have flushed the inside nothing but clean water coming out.

 

[chucksoliver77]

can you see the water circulate when you rev it up? could be the water pump or maybe the thermostat in not opening or not in correctly. chuck

 

[Lil Red]

Water is circulating have tried it with out the thermostate.

 

[RonL]

Before I would start tearing it down. I would get a cooling system check done. With this system, you remove your radiator cap, put on the adapter that fits your radiator top, and pump it up. As stated before, the 77 is a no pressure system, so don"t do much. This will tell you if the system is tight. It has a guage that will tell you if water is getting away. If not, you likely need to cook the radiator out. Your flush is not that great at opening up inside tubes that are plugged. If the pressure leakes down, you need to find the leak. Head gasket, sleeve o-rings, external leaks, all could be at fault.