Thread: Testing thermostats

There's no problem in starting to open at 81 degrees, that's normal. If it started to open at 76 degrees the inrush of cold coolant would would probably make the thermostat 'cycle' a few times till it reached an equilibrium, though I reckon 95 sounds a bit high for fully open but I still wouldn't be too concerned.

Also you need to bring the temp up very slowly when testing to give it time to work as there is some latency involved. ie. if you've gone from 76 to 95 degrees too quickly it may be too quick for the thermostat to operate with the high figure being misleading.

Deano

Didn't even think about the latency. Great point.
My method was something along the lines of

1. Boil kettle
2. dump in a pot
3. hotplate turned to 11 (most people's hotplates only go to 10)
4. Whack the probe and T-stat in.
5. Watch the fireworks

Water temp started at approx 70C when I dropped the unit into the water.
Boiled to 100C within 2 minutes or so...

So definitely room for improvement!

is there a nismo unit toxic, i believe the usually open a little earlier

I've heard that. I wonder if it's also more responsive than the stock unit?

This unit was supplied as part of a service kit. Funnily enough (unlike most 300zx's) mine hasn't melted down due to cooling issues, so I'm thinking my current one is actually working well- Sits on 83*C all day every day. Had it up to 94 in the middle of summer- not bad for a car with no room in the engine bay, twin turbos and minimal frontal area for the radiator...
Although running a big twin pass PWR radiator and new viscous fan helps a lot.