We have struggled with the coolant for forever, but now it's gotten worse. Driving about 10- 20 miles I will lose a gallon, but the car is not wet when I start it or get home or let it sit for a while. The oil isn't milky at all and has been drained a couple times to see if water/coolant was under it but nope. I figured if I was losing that much into a cylinder or the engine the engine would lock up anyway, or that I would atleast notice it, but maybe I'm wrong. My plugs are also not corroded. The water pump, hoses, radiator and radiator cap have all been replaced. The shop didn't know either. Any ideas? Thanks.

 

Do you see any white smoke out of your exhaust?

I would do a cooling system pressure test to verify the system holds pressure. You can usually "rent" the tool from your local auto parts store (Autozone) for free.

Also search on "0331 head leak" as there are many posts about them cracking.

 

As above run a pressure test but if it's losing a gallon in 10 miles and not showing up on the ground or in the passenger side footwell (heater core leak ) I gotta believe it's a head gasket leak into one or more cylinders. The 331 crack leaks into the oil/crank case, if you were putting that much coolant into the oil it would overflow the crank case.

Do a compression test too.

 

Theres no smoke in the exhaust, there is a really small drip though, but I thought that was normal. I have a tupy head, but it could still leak. I'll look at renting that tool though and send an update.

 

I will do that. Thanks for the replies.

 

Ok we have solved the problem. The 2nd O ring under the radiator cap was cracked. Thanks for the help 👍

 

Extra attaboy points awarded for following up by letting folks know the resolution. It's somewhat of a PITA to try to provide a poster with information and never finding out if the diagnosis was correct.