Hello: I had the same problem - but it started with me not having enough coolant in the radiator. The leak turned out to be the coolant housing and it cost me about $300 to have it replaced. It's plastic and the shop got it from Dormer. I dont think the leak would have happened if the engine did not overheat. BTW, anybody know where I can get a coolant reservoir cap - I cant figure out which one to order on-line.

 

The hex plug can be ordered at any Mazda for around 6 dollars 3 if you have a shop account which isn't hard to get

 

Thanks for the tip!

 

Thank you. BTW, how can I order the coolant reservoir cap?

 

This "expansion valve" or "freeze plug" is not for coolant, so if your leaking that, this is not the issue.
95% sure it is the coolant housing in front of it. Known to break on the inner lip causing the gasket to expand inward.

And NEVER, when its a part like this that needs replaced, use jb weld. If it was a crack in the head, ok. But this is not that I assure you.

Part number Dorman 902-690 is for the coolant outlet. You will have fun getting it out .


I am in the middle of this repair for a customer and cannot find the torque specs for the plug since they too were sure that's where it was leaking and it looked like it. But, again, it's oil on the other side of that plug right into your camshafts and lifters ect. Any dealership parts person can print you a diagram to show you if you don't believe me. Since I'm here and they bought the part I removed the plug to replace that as well.


Figure share for anyone else coming acroos this post thinking the same thing my customer did. Pics coming in a second

 

New and old water outlet

Lip that is known to break allowing water to force the gasket inward and even break.

I DID advised her on the oil leaks from the valve cover gasket. New plug installed waiting to be torqued. It was IN THERE TIGHT