Are cooling systems poorly designed ?

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mbunting
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Are cooling systems poorly designed ?

Post by mbunting » 16 Jan 2003, 23:52

I recently had a duff thermostat, allowing the coolant to flow into the radiator regardless of the engine temp.
It ocurred to me that the design of a cooling system is fundamentally flawed, and could result in engine damage.
Let me explain my theory..
Imagine a cold winters day, the engine is warming up nicely, the coolant in the radiator is stone cold.
You come to a bit of slow traffic, and the engine starts warming up, the thermostat starts to open, and the stone cold coolant starts to enter the engine.
I would imagine this would be a bit of a shock to the system, being nicely warm, and then getting cold coolant chucked on you...
Obviously, this only happens the first time, as the water in the radiator would then warm up, and be ( in theory ) a little warmer when the thermostat next opens.
Would it not be a sensible idea to have a radiator loop-back feed, which is perhaps heated independantly of the main coolant, and circulated around.
When the coolant is required, the loop is closed, the thermostat opens and warm coolant circulates into the engine, with the current stuff now being cooled via the radiator.
When the coolant is below temerature, the thermostat closes, the loop opens to keep the radiator coolant fairly warm...
There would be a risk of air-locks forming, but I'm sure a way around that could be found.
Or am I missing something obvious here ?
Mat.

tomsheppard
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Post by tomsheppard » 17 Jan 2003, 15:53

Well the system has worked for about a century although I am told that 2CVs never boil. The temperature at which the stat opens is fairly low and the radiator is amply able to withstand the thermal shock. Many cars now run the heater matrix independently of the thermostat circuit to allow fast demisting and preheating the coolant with a block heater is common practice in cold countries. Me, I'd settle for just knowing that the system is operating correctly...

mbunting
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Post by mbunting » 17 Jan 2003, 19:46

I wasn't talking so much about the thermal shock to the radiator, rather the thermal shock to the engine ( heads etc. ) from that initial rush of cold water into a very hot environment when the thermo allows the first lot of coolant from the rad into the engine.
Mat.

JohnD
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Post by JohnD » 18 Jan 2003, 00:59

But the cold water can't run into the engine any quicker than it comes out through the thermostat housing.

alan s
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Post by alan s » 18 Jan 2003, 02:21

I think the point we're missing here could be the fact that we aren't running cold water into a dry red hot block, but adding cold water to the already hot stuff in there. Just as boiling water poured directly into a cold glass will shatter it, hot water added to a glass already full of cold water will have no adverse effect & will heat the contents of the glass gradually. The route the hot water takes is of course another story and this also can work to reduce the shock aspect but here's another one for you; Why do we have to have water pumps in cars? Is it just designers vanity in wanting to keep their cars lower & sleeker than the opposition? Or is it that they can no longer comprehend a basic theory of physics?
Years ago I owned an Austin 10. It had no water pump but operated on the basic law of thermo syphon; the header tank was set high up under the bonnet & was fairly large. At the time I lived in a fairly large city & close to the State capital which I visited quite often. Remember that I live in the tropics and this was before the days of Governments allowing for heavy traffic flows (You'd be excused for think a lot thought the car was just a passing fancy) so grid locks were more the norm than these days.
I never can remember that car ever boiling, yet today, we have all these fancy solutions, thermo fans, electric pumps, fluid driven fans, special coolants etc. How come overheating was never a problem on an old car with no water pump yet we constantly hear of it with modern cars full of this modern technology?
Alan S

tomsheppard
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Post by tomsheppard » 20 Jan 2003, 14:39

Because engine efficiency and demisting weren't such big issues then.

Homer
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Post by Homer » 26 Feb 2003, 12:58

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by tomsheppard</i>

Well the system has worked for about a century although I am told that 2CVs never boil.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
Errmmmm... Aren't 2CVs air cooled?