mx5cartalk.com

Could be a bad thermostat, or maybe its time for a 3 row aluminium radiator.

Is the turbo very close to the water lines??

Yep I'd be checking the thermostat

I was having major coolant overheat issues last summer. At that time I had a huge intercooler sitting in front of the A/C and radiator, and I didn't have the under engine tray fitted. I have a 38mm PWR all metal radiator fitted. I was seeing coolant temps of around 110c at the time. The only way I could get the temp down was turn the A/C off, which was too good on the late Feb weather (35-40c days). By the way when the dash temp gauge is sitting in its normal position of just left of centre the temp range is between appox 70c and 100c. It only starts move when the temp hits 102c.

Just prior to winter I fitted a smaller intercooler (Thanks Fatty), and refitted my under engine tray.

Yesterday it was the hottest October day for 80 years at 32c. I took the car out and drove at local street speeds and then on the freeway, with and without the A/C on. Not once did the coolant temp climb. I was checking the coolant temp on my ECU display and the hottest I saw was 92c. The intake air temp (taken beween the IC and intake) was around 40c. Turning the A/C on did not make a difference. I am hoping that I have seen the last of the overheating problems (at least on the road), only some hotter weather will confirm this.

How big is the IC?
Do you notice a difference if the A/C is on?
Is your under engine tray fitted? There has been a number of posts on the miata.net forum where it has been shown that the under engine tray does have a big affect on the amount of air flowing through the radiator.

J

I'd expect your old OEM radiator isn't working as well as it use to and it probably inadequate for a turbo set-up.

Your tune could also be effecting temperatures.

Do you have your licence plate stopping any air getting to your radiator?

I had a dead thermo switch which was causing this also.

antmx5 wrote:Thanks guys this is all helping.

I took the car out today (20 Degrees) and gave it a hard time and saw no temp increases out of the norm.

The intercooler is 180 x 560 x 76 (EBAY JOB) and the thermo fan works. Haven't tried the A/C yet. I've put the under engine tray back and it's a very flush fit. The number plate is completely out of the way.

It seems to be that the car struggles to cool once it starts to get hot.

The Smaller thermo doesn't come on, is that just for the A/C? Should i be researching using that fan aswell?

When you say you have put the engine tray back, do you mean after the overheating prob, or before?
The 2nd fan only kicks in when the A/C is on. It is possibel to wire the fans to run together without the A/C being on.
link==>> http://www.miata.net/hakuna/parallel%20 ... iring.html

Unless there was something very wrong with the cooling system then I would be surprised if it overheated in 20c weather. That IC sounds quite big, is it much smaller than the radiator? I suspect that it is blocking much of the air meant for the radiator. Is the black plastic shroud still fitted in the mouth of the front bumper? In addition to the engine tray this helps direct the air to where it is needed.

J

That IC is big for a little motor. Seems very thick so may be impeding airflow?

Some of the possibles have already been covered in this topic, but this is still worth a detailed read through ...

http://www.miata.net/garage/CoolingSystemProblems.html

could make a joined radiator/intercooler combo