We just placed in a NEW engine, along with *all* new coolant/heater and fuel lines, and thermostat, along with a new AutoMeter coolant gauge (100-250 Farenheit). Antifreeze mixture is 60% distilled water, 40% coolant.

I have about 100-miles now on the engine, but have noticed that when cruising in 4th gear (80mph), A/C @ "3"; the engine coolant temperature is about 205-F, and while accelerating will go up to 210-F.

The sensor is located on the front of the thermostat housing. Outside temerature is 54-Farenheit and 75% humidity.

Is this normal ?

If not, what should I do (e.g., fan mod; Koyo/Fluidyne radiator) first ?

Should I *not* boost if my coolant temp is 210-F and higher ?

BTW: I am in Jacksonville, FL, where the summers are 95-105 Farenheit, and 95-98% humidity, but I have 93-octane gas (103 when racing!).

Thanks in advance,
:-) neil

 

operating temp is normally around 221 f. thats when the fans should come on unless you have the miata thermoswitch. I am not sure what "3" on the ac would do to change this. when I turn my ac on "5", my fans come on immediately. check to see if or when your fans come on. the thermostat is fully open at 180 F. verify your fans are coming on. mine went out recently and I had to replace them. good luck.

 

i was having temp range issues (190-225) last spring/summer here in San Diego. upon installing a larger radiator (Koyo) my temps have stayed around 180. i dont believe 205-210 is an issue but if you are concerned i would suggest a better radiator.
your AC kicks your fans in when its running so adding the fam mod wouldn't help what you are wanting to fix. although having one os good to bring your engine temps down gradually when you have parked.

water wetter was suggested to me before as a temporary fix. i didnt notice much of a change but it might work for you.

 

My car, with Stock Radiator/Cooling system @ 60k miles:

Shows 180-190 all gears, all rpm ranges. Sometimes, only sometimes, over prolonged load (or rev'ing a lot), I'll see above 190 to 195 or so.

200 Is only seen when I was in traffic, on a 90 degree HUMID day here in NY...and only then. It went to about 210.

AC-3 is when BOTH fans will automatically come on, regardless of coolant temps. This can help lower you temps, but it also puts a strain on the engine (cause of the AC being on of course).

Best COA is to replace the radiator (I am about to) and try and do the fan-switch mod or Mazda Thermoswitch (comes on automatically at a lower temp). I am going to do the latter soon too I hope.

Oh and FWIW, I also have Stock boost patterns, a high flow MP, and M2 Dual (as far as power mods or heat transfer go's..)

 

I have a mostly stock setup similar to yours. My autometer water temp gauge, which measures at the coolant filler neck, ranges from 180f to 210f. I have a miata thermoswitch which I believe turns on the fans around 210. I've never seen it go higher, and 210 is not too hot. 230f would be too hot, I think.

I usually leave my parking lights on whenever I'm driving, so that I think gets the fans cycling on/off more frequently.

Dave

 

I only wish I had the Miata thermoswitch when I changed out the "green" thermoswitch, so I don't have to take-off the alternator again!

Budget for a new radiator . . . .

Since no one answered it directly, I assume full boost at 210-F is OK.

TIA,

:-) neil

 

210 F is ok, and I would say normal operating temps range from 180-220.

Anything 240 F and above is dangerous; I would let the car cool down if the needle started creeping past 230 F.

 

do you have your undertray on the car?

 

Thanks good to know.

I called the previous owner, and the radiator was changed out two years ago with a Modine aluminum unit. I double checked, and no plastic tanks.

:-) neil

 

Yes, I have my undertray on the car. Just not my tranny tray (it's on order!).

:-) neil

 

in the summertime i always had the gauge pinned at 200f while cruising and it would hit 210 in heavy traffic or anytime when im at a stop..on the highway it would go down for like 190-195..

but now since its pretty cool (30-40 degrees ) i can leave the fans off and the gauge wont go past 175..LOL dont know if thats a good thing or not..but i turn the fans on anyway after about 10 minute into my drive..its a habit..

 

How about people with FMIC? I have a Fluidyne rad and a Greddy FMIC. My temp sensor is in the throtle coolant line. I see temps around 190-210 and when getting on the rev it goes up past 220+.

 

good thing for the bump

yeah i have the greddy fmic with the stock rad and now that its summertime, its pretty damn hot..today and the past 2 weeks has been well into the 90s..i still dont see my car hitting over 190 ever on the gauge..i turn the fans on about 5 minutes into my drive..heatsoak dropped too, last year with my smic, around this time heatsoak would raise my temp to almost 230!..now this year with the fmic, i dont see the gauge go past 200 unless i've been boosting but in this hot weather, i dont do it..

 

I have the blitz FMIC with radiator mounted vertically right behind it, when its sunny and about 90 degrees out at a stoplight I usually dont ever see temps past 203 degrees. I love that FMIC.

Anybody know if i can rely on the water temp reading on my PFC or should I get a gauge?

Also, I would recommend leaning out your mixture of coolant and water. I find that 20% coolant works great with water wetter.

 

Good info. Was wondering what to set the temp alarm to on my SPA gauges!
Thanks

 

185-200f Is Normal...

 

There is a fine line to walk re the glycol/distilled water mix. If you reduce the glycol too much you will boil the coolant too easilly. This is not a problem except you tend to loose coolant when it boils (and it panics you). Boiling coolant actually cools the engine better.

I use a 50/50 mix because my garage is not heated, and in the winter here in the "Great White North" the temps in the garage can go down below -30C. It also reduces corrosion possibilities. Even so, I don't have problems with overheating on hot summer days, even when under higher output power conditions, such as climbing a long mountain pass, ambient temp +30C (around 80F). The coolant temp rises, but not over 105C or so. Stock rad., modified stock coolant temp gauge (compressed range so I can watch it heat up), PFC readout used for "actual" temp indications.

I would say you see normal temps - I see on the highway 85C on "cool" days, 90C on warmer days. In the city, 92C on cool days, 96C or so on warm days. Shut it off on a hot day and restart 5-10 min. later and it will read up to 110C for 10 sec. or so, until the water pump cools it down. That will get your attention!

 

My conditions are very similar and with my Blitz FMIC and Fluidyne.

Anyone know how accurate the readings are from the PFC for water temp, and what sensor it reads this off of?

Also, I change my coolant/water mixture in the winter even though I do not drive it. 50/50 in the winter 80/20 summer.

 

That's not true. Even 100% water in the cooling system will not boil at normal engine temps because it is maintained under pressure. I run 90% water / 10% glycol (or sometimes 80/20) in the 100+ degree Texas summers and have no trouble whatsoever. The car runs noticeable cooler with that mix than a 50/50 mix.

I run some glycol because its additives help fight corrosion of cooling system components and it also lubricates the water pump seals and bearings. Water does a better job of exchanging heat than glycol does. You only need glycol to prevent freezing, you don't really need it to prevent overheating.

 

Boiling coolant does not cool, vapor pockets are built up between liquid and metal GREATLY reducing heat transfer; but anyway's, boiling point is at 250 deg F or so in pressurized systems.

 

Why do people use distilled water?

 

Since it is free of minerals it leaves far fewer deposits and causes much less corrosion in the system. Your entire cooling system will thank you for using distilled water.

 

Everyone has their own opinions, but boiling water removes a lot more energy than liquid water ever could. All you need is a small splash of coolant in a pocket of gas to exceed liquid water cooling. Not that I'm suggesting boiling is a good thing - seems to me I implied just the opposite!

Distilled water reduces the possibility of corrosive products forming in the system. The corrosion is alleged to cause "O" ring failure (re Mazdatrix).

As for lower concentrations of glycol lowering boiling point, read the literature. You get the highest boiling point around 60% glycol. Again, I'm not saying use that. I'm using 50/50, and if you think your situation works best with lower concentrations, by all means use it. I'm just warning that you will be lowering the boiling temp. - not necessarily to levels that you would experience boiling. Be aware however, that at the bottom left of the engine, where the combustion occures, the coolant temp is highest. This is the place the "tiny bubbles" are formed, that the AST is supposed to eliminate.

The PFC reads off the sensor on the filler tube. I would guess it's running "engineering accuracy", +or- 5%. The instrument cluster temp. gauge is the only thing that reads the sensor over the spark plugs.