Well only 3-4 k on an engine rebuild. I bought the car about a month ago with the rebuilt engine and it appears to have a blown seal.

My puke tank started overflowing without reason. So I tossed my radiator cap and bought one at autozone, a prestone 13 lbd cap with relief lever. Same problem, tank is overflowing after driving around and the buzzer hits after shut down and restart.

I did a pressure test. It held 15 lbds no problem. I didn't smell any gas coming from the filler neck, so to elimiate my doubts I used a coolant gas tester and it came up negative.

I did notice that when the thermostat cracks I get some foamy champaign but it dissapears shortly after and any bubbling thereafter looks like the water pump thrashing coolant around.

Are aftermarket caps worth a crap and this is my problem? Or do I have a blown seal that is being a bugger to find?

 

AST still in place? the cap on my filler neck isn't a pressure cap and i have an aluminum ast (pettit), haven't had any problems ?

 

no ast, previous owner removed it.

 

I have autozone radiator cap (with out the lifter) since I've lost my stock cap . It's not causing any problem. FYI, I noticed that cap with lifter did not fit right on the fd...

 

it should have a 16lb cap?.......

 

recall mods included replacing 1.3 bar (19 psi) cap with 0.9 bar (13 psi) cap, many after market caps split the diff with 1.1 bar (16 psi).

IMO 13 psi is too low, Mazda must have taken a very conservative action against a fire recall .. but then left us with cooling problems.

 

i got the prestone square cap. its .9 bar. im going to try another cap today. Im waiting for a mazda one to come in the mail.

 

If your overflow tank is overflowing, but you got a negative test for hydrocarbons, that pretty much rules out coolant seals IMO. Of course, depends how accurate the hydrocarbon test is and how long it's been happening for. I'd look at things like maybe a small pinhole leak somewhere. When the car cools down you could be sucking in air through a small hole rather than sucking coolant back from the overflow tank. Or a dodgy pressure cap. Try the new one and see how you go.

 

ive tried a new puke hose with a jug, it sucks back just fine... just not enough to bring back in the craploads of coolant that was puked. I just got done picking up a pressure cap from kraggen, no dice either. I feel like picking up a 16 lbd one for testing purposes while i wait for the factory cap.

 

A pinhole in another coolant hose other than the one to the overflow bottle could cause similar symptoms.

If you had a pressure tester handy, you could pressure test the cooling system. That could help identify either bad seals or a pinhole leak.