My radiator cap, not the cap on the ast but the other cap seems to leak. I've replaced it twice. Seems to work for a little bit then leaks again.

Any ideas?
Thanks

 

How do you know it's leaking? We maybe able to help a little bit better if you can describe how you arrived at that conclusion.
By the way, what is the pressure rating on the cap you are using?

 

The cap that goes in the place that I'm talking about has no pressure rating. The cap with the pressure rating goes on the ast. I can tell that it's leaking because there is dried coolant all over the neck and sometimes I can even see coolant that hasnt dried in the little screw thing on the neck.

Thanks

 

The black rubber cap seals is probably worn out, cracked, or hardened.

Change it.

Timmy

 

Two bad caps in three months doesnt sound right. Anything else it could be?

 

By any chance is the neck one that is used for the AST elimination, I.E. has the nipple on it. I put one on my motor (one with the nipple) and it leaked as well when I used the non-pressure cap. I don't know why but when I used the pressure cap (.9bar) I had no problem with it leaking so I went back to the original neck.

 

its just a regular filler cap. No nipple. I have a pettit ast. It doesnt really leak that much coolant but it leaks enough in a couple days to cause the low coolant buzzer to come on. Its weird though because my overflow tank level hasnt changed. I figured that if the coolant level dropped it would suck out of the overflow tank. Dont know if that system is working so tomorrow I'm going to drain everything out of my overflow tank start the car and see if the overflow tank gets some coolant in it if it doesnt that will tell me that there is some problem with the line going to the tank.

Any other input would be greatly appreciated.
Thanks

 

Take off the cap and look at your filler neck. I would be willing to bet that sometime (recently) the cap was put on misaligned and you may have damaged the actual neck (two ridges that the cap uses to pull it down securely). Hopefully, if this is the case, you don't have a reman with the one piece filler neck, and you can just simply get a new filler neck piece (you'll notice two bolts at the base). Good luck.

Richard

 

Or maybe the filler neck O-ring is gone.

Timmy

 

On the mazdatrix site they have the second gen neck with out the tube.. is that the same as the 3rd gen neck? If not where can i find the neck for the FD?

 

Very closely inspect the top surface of the filler neck. even a slight corrosion pit there will cause a leak as you describe. Often this can be corrected - I've done it several times on other cars - with judicius use of a flat (machinist's) file.

 

Question, is there a radiator cap that can be used on the filler neck that you can buy at an auto store. I bought one that the computer suggested the other day and i over heated last night.. and the cap was real loose it also came with the spring

 

old thread but i have the same problem just replaced it and again it leaks like crazy!!!
n e suggestions, i know for a fact its not leaking from the neck, its the cap...