So, I just dropped in a new engine. New hoses all around using worm clamps, except for the firewall to pipe hose. New radiator.

I can't get this goddamn car to "suck back" the expelled coolant into the overflow tank. Instead, after every time I run it, air is sucked back instead of the coolant in the overflow tank.

Searched, yes - lots. And I'll be DAMNED if I can get any coolant to leak anywhere on the goddamn thing. I'm not even sure what to search for at this point - I just want to get this working the right way.

 

A friend of mine just had this problem.

the coolant fill cap seals failed, causing the same problem your having.

The solution is to replace the cap with a new OEM cap.

It could also be a bad hose from the fill neck to the overflow bottle. Even if it doesn't leak coolant it may allow air into the system.

 

If you are referring to the radiator cap, been replaced with a new one.

I've replaced the hose with new hose on the overflow as well.

This issue also persists across two seperate overflow tanks.

 

is it a stock radiator? The stock plastic flange can get worn down from taking off and putting on the cap many times and can cause the rad to not hold as much pressure or suck in atmosphere instead of coolant from the overflow.

 

Direct stock replacement, but not a stock one no - pure metal.

Would it be preferable to run a flat cap of some sort in that case, running a coolant hose from the filler neck instead?

 

There are two hose on the overflow tank. Make sure the hoses are going to the right places and not crossed up.

A bad water seal land for the rotor housings (big *** internal problem) could cause this problem also, but nah, can't be that. Cost too much.