Classic cars forum & vehicle restoration.

[shell27]

MVPeters

Hi thanks for getting back, this car as I am told was a front runner for the water pump, the engine was designed to be a siphon type of cooling system.
I intend to get a new thermostat in the new year this could take time but I think everything that has been said on this forum has been helpful.
Steve

[Peter_L]

Steve. What's the water pressure ?.

[peter scott]

Hi Peter,

I think most pre-war cars run with open cooling systems, so no pressure.

Peter
_________________
http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon

[Peter_L]

With the 'stat closed, water does not reach the radiator and the engine warms up quicker. Once the water reaches the 'stat working temp, it opens and allows water to pass through the radiator. OK, so the open stat will create some resistance in flow volume which may suggest the water spends more time passing through the radiator and has more cool air flow to cool the liquid.

But, does the removal of the 'stat increase the water flow enough to cause overheating. A problem that I understand existed while the 'stat was in place, but may have been faulty and was limiting the flow through the radiator.

With the stat fully closed, the engine will over heat because the radiator is out of use, the water is only circulating through the engine.

[MVPeters]

[Peter_L]

Knowing "diddly squat" about the engine design, then the following are just ideas.

1: System pressure. The higher the pressure the higher the boiling point.

2: Thermo-syphon required large and tall radiators. There has to be a reasonable amount of radiator higher than the engine. This is why older cars tended to be high at the front.

3: The water pump. Maybe a later addition to these engines (see first line above). I would guess trying to upgrade the pump would be more difficult than the fan route (6

4: The "bubbles" comments keep coming back to this. Bubbles in a cooling system are as welcome as a "fart in a space suit". Whether they are troublesome or not is very difficult to know without seeing them. Could you e-mail some bubbles for us all to see. ?

5: Radiator Size. Maybe the radiator is just not big enough. or constructed in a way that allows the airflow to cool the water.

6: The Fan..Compensating by forcing more air, could make the engine happy when idling. If you are not going for a nut and bolt perfect vehicle, but want to enjoy the motoring experience then maybe fan/fans is/are the way to a happy life. It could be a case that "size matters"
Perhaps the fan you have just doesn't deliver. A different/custom/modified fan may be an option.

[Rick]

[ka]

I fully agree with the view that a pressurized system increases the boiling point of water, but the common pressure stated on rad caps is around 7-13psi, which will increase the boiling point by a few degrees, but, the system should not be boiling, moderns' run at around 90+ degrees, diesels one or two degrees lower. My thermo-syphon 10Hp, runs at 90-95 degrees, (capillary temp gauge in the top hose).
The previous Morgan we had, showed why white-metal engined cars had their day; when on the motorways traveling at around 55-55mph the temp stayed at around 90, the oil pressure at around 35psi, when at 55-65mph the engine overheated and the oil pressure dropped accordingly.
This Morgan has the original larger rad, containing around 2 gallons of water. Moderns hold less water but run water pumps and more efficient rads, if the car is overheating in traffic the radiator is probably on the edge, so everything else need to be working efficiently as already covered.

Bubbles, is the engine boiling, and the temp gauge naff?
Just a random thought, have you checked the timing?

On a separate point do early water-pumped thermostat engines run cooler than later 70's cars and thermo-syphons, as you state the engine runs at a relatively low temperature anyway?
_________________
KA

Better three than four.

[shell27]

http://s1379.photobucket.com/user/Princes1955/media/006%208_zpsbum80hh9.jpg.html

[peter scott]

[Rick]

Is the heater matrix known to be good internally? Does running with the heater on full help at all?

RJ
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[shell27]

I noticed that I managed to get a couple of photos on if anyone need more please let me know. Well we seem to have everybody going here dont we, there seems to be more questions than I can answer but I shall try.
Everything works on this car and when I say that I mean everything, from heater to brake lights from spark plugs to dipped head lights. I have had the engine out a couple of times as well and it purrs like a kitten when running it has been to loads of places in England and once I took it to Le Mans for the classic 24hr race at that time it did not have a overheating problem. I have no idea where this problem came from but it has been with me for 2/3 years now. The engine takes about 15 litres (3 galls) of water to fill it up it generally spits out about a litre (2 Pints), when I had the new radiator made I was a bit unsure if it should have been left as is or with the pressure cap but I was assured by the rad company this would be ok. I think the thermostat idea is a good one and I think I may have to put an electric fan to the front but it may have to be 2 because it is not very deep where the fan needs to go.
I am going in to the garage now to check if it still takes time to heat up if I close off the bypass and then I shall try leaving the bypass open and just fan on but with both on yesterday it still got hot, i just dont understand why, I dont know if I mentioned I also checked for gases in the water system with one of those liquid glass tube things and it was a negative reading so as far as I am concerned no gases in the water system which means no nasties with the bloke or head.
Keep the ideas coming as I am trying the best part of them as I am going along.
Happy new year to you all and thanks for your input.
Steve

[Peter_L]

Hi Steve.

Did the overheating start after you had the engine out ?

Heater...... who mentioned a heater ?

Just to recap on the pressure system and temp. Ka made a comment about temperatures. The pressurised system would allow the water to get hotter before it boiled. The last thing needed in a cooling system is boiling water.
Boiling water turns water to steam, steam leaves the engine and the water level goes down. The less water the quicker it will heat up and boil leading to more steam and even more loss.

Back to the heater. A very common place for some serious air to reside.

It maybe that, and I repeat "maybe" that all that is required is to "back fill" the cooling system. Connect the town water to the low side of the heater and let it fill the system until it come out of the top of the rad.

[shell27]

Hi Peter

I have not back filled the system ever but when ever I loose or take out the water it seems to leave air locks but I try to remove them by opening one of the heater pipes, it generally shows by the heating pipes staying cold I let out a bit of water and you hear the hiss of air and water escaping. In you last message you say the last thing you need is the water boiling well unfortunately when the car overheats it generally goes to 100C which we all know is boiling point that is the thing I cannot stop.
I have tried a couple of things over the holiday and I have decided to put the original fan back on and find a new thermostat because I did not have this problem a few years back so it must be something I have done. When I first had the engine done it never had any problems apart from a leaking pump and it got hot, I did not notice the temp gauge and the engine stopped, I took the head off and the head gasket had blown, so I got my engineer to skim the head and check and stuck a new head gasket on and away we went, I dont believe that there is a problem with block or head as I have said before all been checked.

[Peter_L]

Relationship between Pressure and the Boiling point of water.

http://www.iapws.org/faq1/boil.html