Need Help With Cooling System
 

Hey, i have a turbo 1.6 with FMIC. Car never runs cooler then 95 celsius coolant temp when moving, and when i stop and idle it goes up to 102 celsius and possibly more since that is as high the ms gauge will read. My temp gauge for car is always at 1230-1 o clock. If its 25 celsius and up ambient temp and i idle long enough car will get close to over heating.

My cooling system right now has:
-Mishimoto aluminum rad with only 1 stock rad fan
-Rad cooling panel
-50/50 water coolant mix
-Stock 195 thermostat
-All bumper shrouding is in place and engine under tray
- My intercooler does not cover whole bumper mouth, one of those buck tooth looking ones so decent enough airflow at sides to rad and through it.
-Still have heater and lines, have used this to help get rid of some heat and it helped.
-No re route but am looking into setting it up.

So what can i do to help bring temps down a bit, will a 180 thermostat make any difference?

Thanks in advance!

Simple answer is get another fan.

70/30 mix, roughly 2 cups of coolant and rest distilled water.
2 11/12" spal, or 1 larger one.
1 water wetter if you want

Do not use Redline Water Wetter with coolant. See here:

https://www.google.com/search?q=water+wetter+brown&ie=utf-8&oe=utf-8

Have you seen this thread?

https://www.miataturbo.net/race-prep...-thread-79930/

Just came in here to point out that this is normal for a Canada car.

A 195 degrees F thermostat is about 91 degrees C. It may only be fully open at 95 degrees Celsius because of variations in thermostats. I would personally run 180-degree thermostat.

If you are going to run that radiator then you're going to need both fans, probably.

Hmmm... Let's discuss the thermostat idea...

The thermostat sets the floor temp or minimum operating temp. It has very little effect on peak temp, unless it is defective or on the high side of its manufacturing tolerance. Managing peak temp is up to the heat exchanger. Swapping a 195 for a 180 should result in the car taking longer to reach peak temp, but it should still get to the same place a few minutes later than it normally would. Running a lower temp thermostat can have consequences, however. The design center for materials expansion in a modern engine is normally 200F +/- 5*. Running much below that for extended periods of time can cause premature engine wear.

Personally, I think the OP should focus on the radiator and fans. That Mishimoto unit is barely better than stock, in terms of cooling performance. I think I saw somewhere that the stock MSM unit actually outperforms it. If it were me, I would do the re-route with a new OE thermostat and add back the 2nd fan and see what effect that has. If the water temp doesn't come down enough, I would upgrade to the 949 Crossflow radiator. If that doesn't cut it, bigger SPAL fans and/or hood vents.

The OP should also think about adding an oil cooler, if he doesn't have one.

Yeah, but I think his floor is too high. 195 is for emissions compliance, not performance or long engine life. Besides that, 2nd fan is a good start.

The 20+ year old motors on our stock fans get weak with age. I swapped the motor out on my cooling fan (RockAuto was having a clearance, it was CHEAP!). Night and day, especially in that stationary idle situation.

It's common for a trailer-towing package (even back in pre-emission days) to include a warmer thermostat. The reason for this is to raise the temperature of the coolant in the radiator. This allows more heat transfer from the radiator (since heat transfer for conduction and forced convection depends upon delta-T). It may seem counter-intuitive, but if you're having overheating issues a warmer thermostat is better. OTOH, if you have excess cooling available, a cooler thermostat can increase output and resist detonation.

The Mishimoto radiator isn't particularly good. If 949 is out of stock on their crossflow, the Koyo Hyper V-Core is another quality bolt-in solution.

Also, as someone else mentioned, water cools a lot better than antifreeze. I understand that you're in Canada, but in the Summer you can safely reduce the amount of antifreeze.

Does not compute.......a 185 and 200 degree thermostat are both wide open at 230 degrees, explain to me how one helps over another with overheating? The only purpose of a thermostat is to keep the coolant from being too low, simple as that.

Hey, thanks for all your comments. Lots of great info!

I did not know the mishimoto was so bad, its gotta be double the capacity of a stock rad so i cant see it being as bad. I am looking into adding a second fan but cant run a stock fan because of my over the rad ic piping and with where i put bov i have little room. Just need to run a smaller then stock fan. I had an oil cooler installed before, did not notice a big difference temp wise if any at all. Also it made my oil pressure too low i found, would only get 45-50 psi when i got on it once everything was warm. I think it just opened the system too much and oil pump could not flow enough.

I cant decide on the thermostat. What is considered a warmed up engine temp, my WUE ends at 165 so not sure why it would take longer to warm up with a 180. The thermostat would start to open at 180, i still think it would eventually run as hot just take a bit longer to get there. Then i guess there would be less time for coolant in the rad. That is where i am lost and cant decide.

Am i okay to tie a second rad fan into the first one, so they kick on together. Or is that too much for that circuit?

How about you post a pic of your setup, you never mention the over the top intercooler piping. There's a lot of ways you can screw up the ducting with that setup.

You have more efficient heat transfer but only until the thermostat closes again? I don't see how more Q for potentially shorter time (I'm making lots of assumptions here) would help you run cooler if you're limited by the thermostat temperature. With a colder thermostat you'd still get to a higher delta T if you're having cooling issues at low delta T.
Legitimately interested, I may be completely wrong.
IMO if you have all the airflow you can get and everything is in working order, and you're still overheating, you need a larger radiator.
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Guys, trailer tow packages of old generally included big radiators, tranny coolers and hotter thermostats (195 back when most cars left the factory with 180). The operating theory of a properly designed cooling system is that you have enough radiator and cooling air that the thermostat can cycle to maintain an engine coolant outlet temperature. In this circumstance, a hotter thermostat produces hotter coolant entering the radiator which allows the same size radiator and airflow to transfer more heat to the air because there is more delta-T. That's it. It's not mysterious.

If you have an overheating turbo Miata with an inefficient radiator and chocked-off airflow and your thermostat (whether 160, 180, 195 or whatever) is wide-open anyway -- then the thermostat obviously doesn't matter. You've got to fix the radiator and/or airflow.

OP, if it is an issue mostly when idling at rest but otherwise OK, then you've got an airflow problem. The OEM fan is really good PROVIDED the motor is up to snuff. The motors get weak with age and yours is probably several decades old by now. I recently replaced my motor with a new one because I was having your issue. It was cheap and easy to do. It made a HUGE difference. Basically, problem solved.

So what does this have to do with the price of tea in China? It's not relevent to the conversation, or cooling a car in general. If you're riding the thermostat then the cooling system is going to transfer any heat made by the motor no matter what the set point of the thermostat is. A 200 degree thermostat isn't going to move any more heat because the thermostat will just choke the water flow back. Pick your temperature floor by your thermostat rating, that's it's sole purpose.

The topic at hand is discussing heat transfer with the thermostat open.

The topic at hand is discussing OPs issue with temperature rise while stopped at idle. You can see in both of my posts that I urge him to look at airflow and, in particular, consider whether his OEM fan motor might be weak.

The discussion on why people select certain thermostat temperatures was a fun side topic that I elected to participate in -- although I did not originate the discussion. It's tangentially related because OP asked whether a lower-temp thermostat might help his problem. Everyone here understands that it will not.

Are you the MT discussion topic police? You really seem perturbed about this. :magna:

I was just thinking that the thermostat might be bad and might not be opening fully and needed replacing. The car should not run that hot at highway cruise with the under tray and bumper mouth plastic intact at 70*F ambient even if it had no fan.

Ooops. I missed that he was complaining about cruise temps too. Celsius confuses me.

Look into putting a slim spal fan. Your stock fan alone and the mishimoto are not enough. I know it because I drove around with a broken fan and a mishi for a few weeks until I got a new one.

The performance of a particular radiator has at least as much to do with the design as with the size. I don't have direct experience with the Miata version of the Mishimoto, but I have helped friends with installations of Mishis in other cars, and besides not fitting 50% of the time, those friends saw little to no improvement in peak temp over whatever stock radiator they replaced. Sometimes, saturation times were longer, and recovery times were shorter, but peak temps were within 2 to 3 degrees F. All you get with the Mishi, besides all-aluminum construction, is increased capacity in an old technology core. That increased capacity alone is probably enough for N/A, but not for F/I.

From Brian Goodwin:

AFAIK, those in the know on this site recommend the Koyo, CSF, 949, and Trackspeed, depending on application.

What oil cooler setup did you have? Were you running at least -10AN lines? Mocal sandwich plate plus -10AN lines plus quality cooler equals success.

As I suggested above, change your thermostat, when you do the re-route. Yours may be at end of life and not opening completely. A 180 thermostat may hold off the peak temp and delay saturation, but only for a matter of minutes. Peak temp is still dependent upon the cooling system's ability to exchange heat, and that delta T is determined by the efficiency of the radiator and the pressure differential surrounding it. You may see lower cruising temps with a 180 thermostat, but only if your other thermal efficiency problems are solved.

There is a prescription for most Miatas detailed in the thread I linked above. The cooling performance you seek is as simple as following it. Lots of experience and wisdom in that thread.

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