Only the S5 gauge does that. The S4 is linear.

The S4 FSM says the thermostat should start to open between "197-183degF", which is obviously a typo. Convert the Celsius fugures and you'll see it's actually 177-183degF, which matches the "180degF" rating. The S5 FSM confirms this. If your 'stat doesn't open until 197degF, you're going to have issues...

207...

 

I don't know.. I think it's a location thing.

I have my AutoMeter guage tapped into basically the same area, right beneath the Tstat (OEM, by the by). Every time I drive my car, it takes about 3 highway minutes to fully warm up, it works its way up to about 215-220 at normal temperature increase speed, then quickly drops down to 180-90ish (well, 200ish if I'm cruizing above 100 MPH for any length of time). I think it's more a thing of the tstat opening sort of slowly, and the hotter water having a chance to sit against the sensor for a few seconds..

I'm not too concerned about it, since it's never shown any inclination to go above 220, and it always drops back down to 185ish. Although I do need to fabricate a belly pan one of these days. Even at that, the stock temp gauge never goes above 1/4 to 1/3rd.

So I'm saying it's due to location

 

I am just off all over the place... Thats what I get for going from memory.

 

Well I just reprimed my system after the first time and 2 runs ^. When the level settled after running it was low. I drained some more water added 30% glycol and 1 bottle purple ice then back filled with water. Bled system ran with cap off toped off and then drove to gas station to fill up for the FL gas shortage :-D. My temps did not surge anymore but my avg cruise and idle temp is 190F.

 

Keep us informed on it, though...and keep a very close eye on your water level. I hate to be a pesimist about such things, but my experiences with 7m's leaves me pesimistic about any kind of cooling problem...

 

Thread pruned for Slpin's flaming--- knock it off slpin!

 

I've always wondered about this number, as the stock system likes to trigger right at 225F according to my SPI electronic water temp gauge.

The "upgrade" is to use the Miata water thermo switch which is supposedly rated at 205F.
No, the Mazda part number is not identical to the FC one, although it does swap in...


-Ted

 

Well that's when the FSM says it's supposed to trigger.

 

Allrighty! I drove the car 200mi's today. I started at 2pm at 95F with 100% humidity with heat index of 110+. All day long idle cruise and so forth with intermittent boosts my temps were a rock solid 193 to 196 to be exact. They never moved more then the 3 degrees between toughs two temps. I drove it all day in that heat and till near 2am tonight with temps dropping into the 80s right now. The temps did not move from their same place as in the day.

Apparently my proper operating temps is 195F in my location. This is 1/2in below the water thermo sensor. I noticed no fluctuations as stated. If my T-stat is opening at 180 then it is slightly open all the time but maintaining a perfectly even temp. This temp reading evens out to be 1/2 way on my stock S4 gauge.

My coolant mixtures are as follows. 1/2 bottle or 2 quarts glycol and one bottle purple ice / water wetter this should be around 1pt I think with a fully back filed system of H20. I am running factory S4 clutch fan with a KOYO radiator.

I have done a good bit of ducting improvements "pics found in my blog" and after this I can only say. AMEN TO DUCTING! Thank you J-Rat for the inspiration.

 

I am telling you.. If you have an FMIC, ducting is WHERE ITS AT... Now there are 2 people that have proven that fact..