All,

I have replaced my thermostat 3 times this fall. I have purchased each of them at the local Napa. I tested them in boiling hot water after they would not open and the temp gauge showed an unsually high reading. Any suggestions? Should I just get one from Mazda? Anyone esle experience this problem?

Jim

 

You know, in reality thermostats "fail" about one in one hundred million times.
On the FD, it is NEVER the thermostat (well...nearly never), it is almost always coolant seals or other system woes.

The fact that you have evidently got a bunch of them from NAPA that don't work seems to indicate a bad batch. I would take them all back.

And yes, the OEM 'stat is the ONLY one recommended.

 

IIRC, the OE stat has a block-off for a coolant bypass that should be open cold, but not once the coolant warms up. Many aftermarket ones leave this out, causing the coolant to recirculate after warmup, which causes overheating, or at least higher coolant temps.

 

After buying 3 bad ones at Napa, maybe its time for a change. A t-stat is a pretty important part in an FD. Why buy a crappy Napa part?

 

Yup, all rotary motors have a bypass in the front iron. The OEM thermostat has a plunger on the back to block this passage when the T-stat opens.



Paul