Boiling Coolant and Overheating when left idle?

[NitroDann]

It will overheat with no fans on.

trust me.

Infact, dont trust me, unplug your fans. Its winter it'll be right. Right?

Dann

[Okibi]

project should know better than me but cooling fans are there for extremes. Automotive cooling today is normally well in advance of normal operating conditions. Witness what users do in extreme climates like Northern Aust and the Middle East. Idling your MX5 in traffic without a fan I do not believe will cause boiling unless there is an underlying problem.

This is VERY bad advice with expensive consequences, i'm gob-smacked.

Even with a very expensive radiator and oil cooler my car still climbs up to 98"C at idle (and then the fans kick in), not prepared to see just how hot she gets without the fans on

[SuperMazdaKart]

Someone has an old school Volkswagen Beetle engine in an MX-5?

[Locutus]

i've never seen a water cooled engine at operating temp idle for more than 10 mins without thermo fans activating

... well, water cooled engines with working thermo fans, anyway.

[manga_blue]

project should know better than me but cooling fans are there for extremes. Automotive cooling today is normally well in advance of normal operating conditions. Witness what users do in extreme climates like Northern Aust and the Middle East. Idling your MX5 in traffic without a fan I do not believe will cause boiling unless there is an underlying problem.

This is VERY bad advice with expensive consequences, i'm gob-smacked.

Even with a very expensive radiator and oil cooler my car still climbs up to 98"C at idle (and then the fans kick in), not prepared to see just how hot she gets without the fans on

On the surface it sounds like stupidly bad advice but in my experience Morlock is not that far off the mark for once.

A well maintained standard cooling system on an MX5 is a pretty good little system. For all the bullshit about big radiators and ducting on this forum how many members have actually boiled their cars if the coolant is clean and the normal pump and thermostat service checks are done?

I used to live in inner city Melbourne and used the car as a daily driver there. Wall to wall traffic, standard radiator and cooling system. I took me 2 years to discover the previous owner had disabled the fans. That only happened because I sat idling on the grid at Calder in the sun when it was 37 in the shade for 15 minutes with the A/C on waiting for Bruno to recover yet another terminal Alfa. For the rest of the time I'd never noticed the temp go appreciably above normal. I reckon spending on big radiators and fans is one of the biggest wastes here.

[NitroDann]

My personal experience is that it only takes about 10 minutes of bad traffic in summer with no fans to get the car 'too hot'.

A car left idling with no fans will certaintly boil at some point, it simply cannot dissipate enough heat through the radiator through natural convection alone.

Also, my car overheated on the track, n/a, with the stock radiator, and I overheated the stock brakes badly, and I surged the fuel below 1/4 full, all things that apparently dont happen in n/a cars.

i think its fair to mention that MOST people who have big alloy radiators have so because they are cheaper than factory when the stock one fails.

Dann

[Okibi]

... I took me 2 years to discover the previous owner had disabled the fans....

I had a broken clip on the front temp sensor on my NA6 (after market radiator). It was also months before I saw temps rise above normal but i'm very glad I noticed and was able to fix the problem. It wasn't a particularly hot day but I can confirm that with a quality radiator, newish thermostat and coolant the car was beginning to overheat at idle because the fans weren't running.

[Roderic]

Going to test if my fans are working via the Ground/Pin 10 Diagnostic trick.
Will also change the Thermostat when I do the radiator change.
Fingers crossed all goes well.....

[Roderic]

Looks like I have at least 1 bung fan.
Did the ground to pin TEN thing but nothing happened
With the car off I tried manually turning the fans, the driver side one turns freely yet the passenger one is very stiff.
Then I turned the car on with the AC and only the driver fan spins.
Looks like a new fan? anything else??

Thanks
Rod.

[egads]

Yeah looks like the radiator (passenger side) fan is gone. A/c (drivers side) fan is only meant to come on with a/c.

Ring around to your local like mania or mx5 plus, think I picked one up from plus for like $50? + shipping. 2nd hand of course.

Oh and once you've got another fan, wire it up and do the gnd-ten to make sure it works, install, go for a little drive, come back and let it idle and wait abit for the fan to come on.
If it doesn't then you'll need to look into thermostat/thermo switch issues.

[RJ45]

Does it still overheat when you have the A/C on? (to have at least one fan going)
Can you swap any wires to get the A/C fan to trigger instead of the bung fan? (as a temp fix)

I'm intending to keep my 5 for a while, so just curious about this
Thanks, Rob

[Roderic]

I'm going to change my radiator to one of the ASI 42mm ones, so ordered the kit from ASI which includes 2x new fans.
I didnt leave the car running on idle for long with just the A/c fan, just incase it was going to overheat.
Also have a new issue which started after playing with the Ten/Ground, I now have a loud metalic ticking noise coming from the engine.
I did also adjust the idle screw (turned it a little anti clockwise) to try and fix the dipping idle issue after changing exhaust system.
Not sure if it is just coincidence, I have checked the oil level with the dip stick and its in the middle, not low and not full??

Time for more playing.

Regards
Rod

[Roderic]

Update,

added more oil to bring it up to 3/4 to the top of the dipstick, went for a 10min run and ticking seems to have gone.
Hope it is not a cold start issue.
Does anyone know if the pin TEN/Ground thing will still work as I'm running a Wolf 3D V4 instead of the stock ECU?

Thanks
Rod