thermostat, which way up?

[FlyingScot]

I know I should know but. I don't.
Anyone?

[MoggyTech]

Bit with the three bar cage up. The top looks more 'curvy'

[FlyingScot]

Thank you.

[bmcecosse]

I doubt you would get the cover on wrong way up!

[badfelafel]

here's my workshop on changing the thermostat:

http://www.brosh.co.uk/Minor/thermostat.html

[wibble_puppy]

nice one badfelafel

[aupickup]

and some have top written on and this way round and to rad

[rayofleamington]

here's my workshop on changing the thermostat:

you missed out the section where the studs sheared off when undoing the nuts, the housing had corroded away so there was hardly any left when you removed the radiator hose - and the remains had corroded and siezed to the studs so had to be taken off in small broken pieces...

As for your thermostat test - the boiling water cools to much when you pour it into a cold bowl. The better way is to put the thermostat into a pan of water on the gas and bring it to boil then watch it as the water cools.
Ideally test both thermostats at the same time so you can see if one opens/closes later (or not at all).

Thermostat's: They are pushed closed by a beefy spring. They open by having a lump of wax in a little metal pot - when the wax gets hot it melts, whereby the melted wax is much bigger - this pushes pushes a plunger out, opening the hole for the water to get through.
The little pot of wax has to sit on the HOT side (ie towards the engine not the rad) - so if it's not marked up properly (e.g. TOP or 'RAD') it should be possible to work out which side is which - just in case you ever wanted to know on any other car.

They can fail jammed open but most likely failure is the wax leaks out - generally if that happens they wont open at all.

[wibble_puppy]

thanks ray i love knowing how and why things work - yer a star