How hot is too hot?

[OurCognitiveSurplus]

Thanks for your help everyone. Car went into Dave at Carco on Friday who flushed the core and changed the thermostat. Turns out he did change the thermostat when he did the radiator last service.

He said that there was some crap in the heater core, but it wasn't too bad. He suggested that creeping a little past vertical on cool-down after a hard run on the track is nothing to be worried about and is fairly normal. Given his experience with tracking various MX5s I'm not inclined to disagree.

So all sorted it seems!

Cheers
Greg

[Steampunk]

Was it a particularly hot day that day at the track?

I'm sure you'll keep an eye on the temp gauge every time you drive, but don't get too trusty of new thermostats.
It's not uncommon to hear people installing new ones and only to have it not work properly for one reason or another.

Just because something is new, doesn't mean it's guaranteed to work 100%, but hopefully things have been fixed.

PS: as an aside, JUST IN CASE you resort to putting in Redline Water Wetter, Purple Ice etc etc. please read expert advice before making a decision.

[OurCognitiveSurplus]

It wasn't a hot day, I'll keep an eye on it.

I'm disinclined towards adding anything to enhance cooling. Physics tells me that there's basically nothing better than pure water for cooling. We need to add antifreeze/anti corrosion... but that's all I'm interested in adding.

[OurCognitiveSurplus]

Thread revival for anyone doing searches.

Turns out the water pump impeller has seen better days. I never would have thought that the pump impeller would be a point of failure. I figured the bearings etc in the pump (leaking and squealing) would go long before the impeller itself kicks the bucket.

The more you know!

[jerrah]

When I bought my NA6 it overheated on day 1.

Cause: Thermostat.
Replaced thermostat with a new one and car still overheated.
Sourced 2nd hand OEM thermostat from MX5plus. = Win.
Still using that thermostat 4+ years later.

I'm guessing your impellers had corroded? Has your car always had good coolant?

[OurCognitiveSurplus]

Knowing what previous owners did or didn't do isn't easy. The pump didn't get changed with the belt at 100,000. So maybe it was just time (140,000km and 15 odd years is a long time) or maybe the coolant wasn't as well loved as it should have been.

The car is in with Carco today for the third day running. Scared that the bill might be huge, but at least the car will be mended.

I suppose the moral of the story for those playing along at home is that an MX5 water pump may fail/decay silently before it starts to squeal or leak water.