the saucepan told me fibs?

[littlejim]

(here under false pretences this is about the Prado not the TR)

 

after the head gasket replacement the Prado seemed to behave itself.

The recent fishing trip to the coast put the temp gauge up the top of the scale.

 

When cool checked water level - OK (gasket hasn't gone again)

Soon learnt that with the heater on full bore I could keep the temperature around normal with the heater fan speeds. (Demist position made it bearable.)

I assume this means the water pump still works reasonably well.

 

Huffed and puffed through all the hoses and radiator with the correct results.

 

Put the thermostat into a saucepan of water on the stove seemed to open at round the specified temp. However can't tell if the amount of opening is the maximum it can do.*

 

re-assembled the cooling system without thermostat and went for a long drive with hills and a few revs. Seemed to behave close to normal, even though it went higher than normal on some of the hills, it came back to normal at idle, which I expected to be the hottest reading I would get.

 

*getting a new thermostat anyway will compare the opening widths in the saucepan before putting it in.

 

What have I missed?

 

[littlejim]

First thing I missed was re-doing up the radiator drain tap, just discovered it. Luckily only lost a half pint.

[littlejim]

Testing the old thermostat in a saucepan of water revealed that it opened at the correct temperature but I bought a new one anyway.

 

Tested the new and old together and found that ‘opening’ proves nothing, it is how ‘far’ they open. The new one opened about 3 times as far as the old one.

 

The new gasket looked too small# so I used the old one (Both had a ‘little groove’ in the middle which I took allowed a bit of compression. Water leaked out.

#

Had another go, this time with the ‘jiggle valve’ on top* more trickling sounds. I then twigged that the ‘little groove’ was for the edge of the thermostat to go in (pic below) before re-fitting. No leaks after that.

 

* one of my manuals doesn’t bother to mention its position (as well as not telling how the gasket goes). The other manual tells you to put it at the bottom (as well as not telling you to prefit the gasket). I decided putting it at the top would be better for air bleeding. Most other car manuals seem to say put it at the top.

Edited November 17, 2013 by littlejim

[Andy Moltu]

Not sure air bleeding is that relevant - your stat would appear to have a small hole in it with a small loose fitting dongle in it - approx 1 O'clock on your photo. That is the air bleed hole.

[littlejim]

Not sure air bleeding is that relevant - your stat would appear to have a small hole in it with a small loose fitting dongle in it - approx 1 O'clock on your photo. That is the air bleed hole.

Andy,

I hope you won't be too stunned to realise I had actually worked that out and decided I would have it uppermost.

The slow bit was working out I had to prefit the gasket to the thermostat.

 

Lesson was: looks like a serious overheat jiggers the thermostat.