THSCC Forums

After finding the Miata running hot at VIR in June, I am trying a couple of cheap fixes. The car runs fine and does not overheat except on the track in 95 degree weather. AX fine, highway pulling trailer in 95 degree weather fine.

I have changed/flushed the radiator, changed the thermostat, new coolant etc.

AFter I did that, I of course thought of maybe checking the fans. Jumped the diagnostic and the left one turns on, but not the right. Are they sequenced, should they have both turned on?

Thanks

Rob

I'm betting the 2nd one doesn't turn on unless the A/C is engaged. - AB

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'14 Toyota Sequoia Platinum 4WD
Super Westerfield Bros - '93 Integra - LeChump Du Jour
STX 93 - Scion FR-S

WINNAR!!! There is a way to jumper the thing always on, search .net

Also thank Mazda as it didnt think it necessary to engineer the Miata with:

-A adequate sized bumper opening to allow air thru.
-A adequate sized radiator to cool the car with.

You have also been closer to overheating and just never known it. The stock water temp gauge is HORRIBLE. If the coolant is 180° to about 215° its the same position on the gauge face So once the needle starts to move, there is little room to play with. I have a aftermarket water temp gauge and recomend one to anybody tracking a Miata. You would be surprise how hot water temp gets in normal driving and track driving.

I also just happen to have a spare adapter that you can install a temp sensor in the upper radiator hose, PM me if interested.

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02 Focus SVT
STF 9

Could the fix be to install an oil cooler to help with overall temp reduction?
Never had any overheating problems with my car on track, but intend to install an oil cooler soon... Just seems like a good move.

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Brad

Couple of posts from Miata forum:

The fan isn't needed at all, 90% of the time since more air comes in the nose when the car is moving 30 MPH or more than the fan could ever hope to move

When the car isn't moving fast enough, the fan comes on based on the temperature of the water exiting the radiator (why would you want it any other way?) which improves the efficiency of the radiator

If you need 'improved cooling' for some reason, buy a larger radiator and leave the fans wired just as they are

Another one:

One VERY IMPORTANT aspect to improving cooling is reducing the amount of Glycol in the system as much as possible AND adding WaterWetter. The liquid that transfers heat from the engine to the atmosphere (IE: radiator) needs to absorb energy as efficiently as possible. Glycol is a VERY POOR liquid to use for heat transfer but a necessary evil up north. I run 15 percent Glycol and 12 ounces WaterWetter and have seen SIGNIFICANT drops in engine temperature and engine compartment temperatures.

For whatever it's worth...

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Brad

Ryan made the waterwetter suggestion too and I think I'll try it. Don't have to worry too much about freezing down here. Bigger radiator will knock me out of stock class now that I went back to the OEM breather for NCAC and at this point I am not willing to modify the car enough to be CSP competitive, so i must use the stock radiator.

I'll try your mix.


Thanks
ROb

I use the water wetter solution in my Datsun 210 with 50/50 coolant. I have seen a 15 to 25 deg reduction in water temp. My problem is in town in 90+ deg days with the AC on.

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George Bright Member # 141
One of the youngest of the old farts.
Yes I voted against you joining the club.

I hope you have better luck with Water Wetter than I did. I never noticed any improvement at all. But if you're going to use it then cut the antifreeze down. 50/50 is too much antifreeze. 75/25 and make sure the 75% is distilled water.

So did you try any of the things we discussed yesterday???

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http://www.greywinds.com

You won't notice any temperature difference from the sensor using Water Wetter; the sensor is far enough away from the block to see anything, and any difference would be within the margin of error of the gauge. WW is a surfactant used to keep localized boiling from happening inside the block which insures better metal-to-coolant contact and more efficient cooling. There's a whitepaper on this on the Red Line website.

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Has no responsibility whatsoever.

Good suggestions everyone!

I also run a 75/25 mix.

You can also maximize the airflow that you DO have by using shrouding to make sure that every CFM of air has to go THRU the radiator.

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02 Focus SVT
STF 9

Never payed that close attention to how the Miata gets air in. But if it is mainly a bottom breather like the Vette then it needs the small airdam/splitter underneath to bring air up into the radiator. If it doesn't use this then I don't see why you couldn't fabricate a simple one and attach it to the lower radiator support. It could be easily removed for AX so as not to make the car illegal.

The oil cooler is a nice idea if you don't mind it messing up your AX class. My oil temps looked good at VIR in a 25min session, high rpms, almost 100deg afternoon. My oil temps are a good 30deg lower. It inderectly helps the cooling system since the oil temps aren't as high and escalating the coolant temps in the block.

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http://www.greywinds.com

BSSSSST!!! We have a belly pan that covers the entire front of the motor. Miata's get ALL their air thru the mouth of the bumper, hence my earlier comment.

An oil cooler will help to some extent (I saw 260° oil at VIR-G) but the only real solutions is a bigger radiator or better shrouding. I think an accurate water temp gauge is the first key to see what is ACTUALLY happening.

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02 Focus SVT
STF 9

Ok that makes sense. Did you fab your own shroud to improve air flow? Does it come with one?

Yep I was running right around 260° on VIR-GE too.

I agree on the gages. Didn't realize the Miata one was innacurate.

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http://www.greywinds.com

Rob,

Lot's of good advice already given

- I'd start with the 75/25 water/coolant mix.
- Do you know the rad cap holds pressure?
- Have you done the coolant reroute?

Proper air ducting and shrouding is very important, because as Ryan said that bumper has a small opening. You want to ensure that all the incoming air flows through the radiator and not around it. I

Numerous larger rad options also available.

Frank

Excellent suggestion. I would just go buy a new cap and t-stat for posterity.

Coolant re-route is not stock legal.

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02 Focus SVT
STF 9