Saturday, May 17, 2014

Testing The New Thermostat

Slowly but surely I am getting around to rebuilding a spare head. So far I've cleaned off all the grime, lapped the valves into their seats, done a little porting (badly) and refurbished the rockers. Still on the 'to do' list is the job of reassembly. But to do that, I needed some new parts.

After some careful internet window shopping and price comparisons, I bought all the parts I needed online from Mini Sport. This is my first purchase with Mini Sport as in the past I've generally used Mini Spares, but for the parts I needed this time, Mini Sports was the cheapest so I thought I would give it a shot. 
Shiny New Things!!!

Among the various purchase items was a new thermostat. You would have thought that buying a new thermostat would be easy, just search and add to the shopping cart and away you go. But unfortunately, it's not quite as simple as that. A quick search on the website brings back not one, but a whole range of items to choose from. To the untrained eye, (i.e. mine) they all look identical, but a closer inspection reveals that the difference is down to the operating temperature. The main choices I could see were 74°C, 82°C and 88°C, however the website descriptions for the differing items offered little to no clues as to which was the best one to use with a standard 998 carb fed engine. I assume that if you get the wrong one it could be bad, probably very bad. So after a quick phone call to Mini Sport Customer Services, I was directed to the 82°C item.

As there was a selection of different thermostats with different temperature thresholds, I thought it would be fun to see just how closely to the stated 82°C it would spring into action. So I devised a little experiment...

Moving to my laboratory (the kitchen), I gathered together the necessary equipment to conduct the experiment. The specialist apparatus used include a kettle, a cup, a thermometer and a draining board.

Very Technical equipment.

After boiling the kettle, the hot water was added to the cup and the thermometer confirmed it was pretty hot, too hot in fact, so adding a little cold, brought it down to about 80° C. Leaving the thermometer sat in the water I could see the temperature dropping from 80, to 79, 78 and so on quite quickly, so I kept topping the cup up from the kettle allowing it to overflow to try to keep the temperature stable.

Plopping the thermostat into the water at 80° C, I expected nothing to happen as this is below the opening temperature. And a few minutes in the water soon confirmed that the thermostat did indeed stay closed.

Adding a little water to the cup, raised the temperature of the water up to 83° C, and now things started to happen.

Slowly the thermostat came to life and started to open. First a little...

Then more...

until it was gaping...

All the time, I tried to keep the temperature at about 83° C.

This seemed to be very close indeed to the operating temperature, these things obviously work and work very well. As a final test, I let the water cool and as the mercury dropped, the thermostat predictably closed back up again.

So there you have it, a very good result confirming that the 82° C thermostat does indeed open at (or very close to) the stated temperature.

With all that sciencing complete, I now just need to tidy up now and allow the kettle to fulfil it's proper role and make a well earned cup of tea.

<Next Post> - 'Spare Engine - Painting the Head'
<This Post> - 'Testing The New Thermostat'
<Previous Post> - 'Oil Change Number 2'

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