Cool/Heat: 1960 Lark

[mlnj]

I have a problem with the cooling system. If I run the car without a radiator cap on the car runs fine. When I run it with the cap in place, water gets in the cylinders and empties the radiator and the car overheats. I changed the thermostat and tried a new radiator cap(13lbs) to no avail. The engine is the 170 inline 6. Does anyone have any ideas?

[Ross]

I am curious how you know the water is getting in the cylinders, but in any event the most likely problem is a blown head gasket followed in likelyhood by a cracked block or head. Usually such problems show themselves by forcing water out of the radiator overflow, large bubbles appearing in the radiator neck, and overheating whether running with a cap or not.

[mlnj]

Thanks for the info. I did check the compression in all the cylinders which was fine. I thought it might be the head gasket, I guess I will try changing the gasket first. However the car does not overheat with the cap off. I could tell it is getting into the cylinder because of the white smoke coming out of the exhaust and if I put my hand on the exhaust you can fell the vacuum without the cap on there is no vacuum at the exhaust.

[swvalcon]

Get a pressure tester and pump up the radiator with the spark plugs removed. Then jump the starter or have someone hit the key while you watch you should real soon which cylinder is the guilty party.

[studegary]

Thanks for the info. I did check the compression in all the cylinders which was fine. I thought it might be the head gasket, I guess I will try changing the gasket first. However the car does not overheat with the cap off. I could tell it is getting into the cylinder because of the white smoke coming out of the exhaust and if I put my hand on the exhaust you can fell the vacuum without the cap on there is no vacuum at the exhaust.

I was with you right up to "vacuum at the exhaust". I can not figure how you are getting that.