SP250 Thermostat

[daimlersteve]

Hi- all across the ditch,
I'd invest in a craig/davies thermo switch from Super- cheap, Great sensitivity, just installed one myself.
Then in the summer you can dial in 165# and in winter up the temp. Make sure you are getting 12v at the fan relay, it makes quite a difference to the fan speed. just running the relay off the ign switch will have a voltage drop, so feed the relay straight from the fuse holder.
Dont run without a thermostat as you need to have some resistance ( hold back ) in the block/ heads . Even in highly stressed race cars a restrictor plate is used instead of a thermostat.
steve

[daimlersteve]

PS, Adding Red- line Water- wetter will drop the temp from 200# to 190# immediately so would be good in the 40# Victoria summers ,half a container does the trick.
Every sp has its own amount of gunge in the block/system so all behave differently but generally if worked hard on hills this will bring the temp up.

steve

[wejxf03]

Daimlersteve, can you elaborate on why you should not run without a thermostat fitted?
I've been running my SP without one for years.
I assumed (possibly wrongly) that this would give a freer circulation of coolant while accepting that the warm up time would be longer.
thanks

[daimlersteve]

Hi John,
an engine wears most before it gets to operating temperature , one of the main anti wear ingrediences in an oil is Zinc. Zinc does not become effective until it ts hot. Even synthetics have a percentage though their makeup is more suited to moderns with closer tolerences. Most power is produced at 170deg F, (David Vizard among others has exhaustively Dynoed engines to prove this) , but that is not effective for cat converters, so isnt the norm these days, not that that is a consideration in our world. Sorry i digress !!
steve

[Phillmore]

Dont run without a thermostat as you need to have some resistance ( hold back ) in the block/ heads . Even in highly stressed race cars a restrictor plate is used instead of a thermostat.
steve

Is the resistance to ensure the water gets forced down all the waterways rather than circulating too quickly down a path of least resistance?

[silverdart]

Hi Michael, Years ago I always had the problem of the engine running hot, Similar to yours.
Then I had the radiator re-cored and since then, the temp. gauge needle sits at the start of the normal arc and the fan only ever cuts in after about 15mins. of heavy traffic.
Do you know the history of your radiator?

Regards Dave.

[Crossley Stephenson]

I have looked up the paperwork that came with the car and it seems the radiator was last out in early 2007. Maybe time for some attention.

Cheers
Michael