Radiator overflow

I have a 23-4-35. When I fill the radiator and drive the car I lose a lot of water through the overflow tube. I have no leaks in the cooling system. I suspect I have a blown head gasket or a cracked head. Before I pull the head I was wondering if anybody has any other idea of what might cause this.

Darryl, If you fill the radiator, you will always get some water coming out the overflow tube as the engine heats up. Look for bubbles in the top of the radiator. ( a good sign of a cracked head gasket ) Do a compression test on all four cylinders. Check the water pump packing, air maybe being sucked in there. You don,t say if the engine is over heating or not.

Check these easy things first before spending more time and effort on other possible causes.

If you get foaming overflow, it is often due to a collapsed hose on the suction side of the pump (bottom hose from the radiator). Make sure you have a firm hose with a spiral wire in it to prevent this. Starving the suction side of the pump will cause cavitation that creates foam in the coolant that will displace more liquid while the engine is running.

If you do not have foaming, just fill the radiator until the core is covered and leave most of the top tank empty to allow for normal coolant expansion.

Darryl,

You could hook up a small (quart) overflow tank by slipping some clear plastic tubing to the bottom of your radiator's over flow tube, bend it into an "S" shape and down into the bottle.

That way you won't "mark your territory".

I hid mine under the fender.

Mike in Colorado

I had foaming and overflow even with an overflow bottle on my 38-41. It overflowed enough to fill the bottle. Turned our to be a cracked head at the valve seats of #8 cylinder. The block around #8 cylinder was almost completely clogged with rust and sediment which had to be manually dug out. This prevented the #8 cylinder from receiving coolant and led to the hot spots.

Hopefully yours in only a bad head gasket.

Steve D

Here are a few more details on my over flow problem. 3 years ago I had the radiator cleaned and repaired (Santa Monica Radiator), replaced the packing in the water pump,and replaced all the hoses (they don't collapse). What happens is the water will surge. With the cap off, it will hold the water level then over flow out the filler pipe, hold the water level then overflow again. It will repeat this until most of the water in the upper tank is gone. The engine will run a little hotter than normal but does not over heat. There is no foaming. It is like there is a pressure build up in the cooling system.

Darryl:

I did the same as you but had the radiator re-cored. Now, it does not overheat but still does foam up. The photos are from my attempt to drive to our Mason-Dixon car show in June of 2013. I had the radiator cleaned and it was pronounced good for service. I added the overflow tank as recommended by Flyer15015. The previous week I had driven it all around our town on 85 deg. days running for over 45 min at a time. No overheating or spit ups. But, when we went to drive it out of town to go up to the show (44 mile) trip this is what it did at the Chambersburg city limits.