For over a year now coolant has been filling up in the reservoir and not being pulled back into the rad. It's not loosing any coolant, just the little bit I spill every time I dump the reservoir back into the rad. The car is not over heating but I think it should be running cooler, I have no interior heat, the car can sit for two days and when I pop the rad cap there is still pressure in it. Everyone's first guess is blown head gasket, it's a four layer steal gasket with a.r.p head studs, but there is no coolant in the oil or bubbling in the rad or smoke from exhaust. I've had compression tests done and head gasket looks fine. I've tried new rad caps, thermostats, water pump, I don't know where else to look. Any ideas would be greatly appreciated.

 

The simple answer is to have a leak down test. The cheap answer would be possible clogs or issues with the radiator nipple and the line going to the overflow bottle.

 

There is your problem. This is why the engine doesn't suck back the coolant from the overflow tank. If your fact is right that you don't have a blown head gasket, then, you have too much air bubble trap in your engine. Bleed it out to see if that fix the problem. And again, you may have two problem going on at the same time where the other one ins a hole/leak in your over flow system: tank, rubber line, radiator over flow nipple.

 

Trapped air is always a possibility. Park your car on an incline with the headlights facing up, remove the radiator cap, put on the e-brake, start the car and let it warm up. If it doesn't start to overheat, leave it running for a while. The air should work its way out.

If you have "boiling in the reservoir tank, it can be a blown head gasket or just a faulty radiator cap. If you can afford 60 bucks, go to NAPA and buy a block tester. That will let you know for sure if you have a blown head gasket. Radiator caps are cheap. Buy a new one just in case.