Leyland P76 Owners 2006

Technical

Why have Thermostat ratings

I have been interested in why we need thermostats for quite a while now but I seem to run into differing points of views.
I thought that they were used to restrict or release the water through the engine by way of the radiator so as to keep the engine at a temperture determied by the manufactures indicated on my guage (in the green). If it went hot (moved to the red) then I need to do something about water flow and cooling.
I am still not the wiser but I will let Mike Chadwick comment further.
Cheers
Adrian

"Heat Management", not "Temperature-Gauge-Reading Control"

by Mike Chadwick
I think that Graham put things well when he said that we need not worry about what the temperature gauge says so much as to allow the cooling system to do its job in varying conditions.
It's as if, for most people as it was previously for me, the 'N' is the only/highest point on the temperature gauge where the needle should point when the engine is at 'normal' running temperature, at all time.
That expectation is not a realistic one.
The gauge shows what the temperature is at anytime, and what it shows is as much due to changeable/varying ambient conditions as it is to the working engine which produces the heat.
Both these factors influence what happens at the radiator, and to what ultimately shows on the Temperature Gauge.
What is happening [rate of heat loss] at the radiator is controlled by the temperature of the coolant coming into the radiator and ambient conditions, creating a temperature differential.
The greater the temperature differential, the greater the heat loss to the ambient air.
That's where a thermostat opening at a slightly higher temperature works its magic.
The name of the game is "Heat Management", not "Temperature-Gauge-Reading Control".
A motor is not overheated until it boils; and that is also managed by sufficient of a suitable coolant inhibitor/anti boil - anti freeze and the correct radiator cap that properly seals the radiator.
Both these are important to increase the boiling temperature.
So you can see, the coolant can be made to run well above the natural boiling point of water by these two points alone.
If the seat in the radiator filler neck is damaged [adversely affecting correct pressure build-up in the cooling system], ask your local radiator man to put on a new filler neck; it's not expensive.
In the mid 1980s I drove my Targa to Alice Springs and back.
My cooling system was stock standard [82 degree thermostat and 2 row core radiator like yours] with an air conditioning condenser in front of the radiator.
During 1984 the engine had been renewed - new pistons, rings, big ends, mains, etc.
I found myself driving north to Alice with ambient temperature at about 45C with the airconditioning working.
The temperature gauge read at the top of the 'red' all day, but the car did not stop all the way.
I considered all the expense of the engine rebuild a total loss all the way to Alice, but it still kept going.
I shuddered to think of the state of the bores and pistons and valves, so as long as it kept going I determined not to bother myself about it too much.
Thoughts of BIG radiators and low temperature opening thermostats continually went through my mind, thinking of another rebuild years later.
In the following year Jim Wallace bought the car from me for his son. I warned them against buying because of rust and the 'abused' engine, so I thought.
They went right through the car, checking it out.
The engine was found to be in perfect order.
My conclusion, riding in the 'red' all day is not damaging so long as it doesn't boil.
This was before I did my research on cooling, but one of the factors leading up to it in the late '80s.
I must go now,
Best wishes,
Mike Chadwick.
Photos of the radiator types are located on Mike's home page
Last updated
April, 2008
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