p3 75 temperature problem.

[deckell]

Can any one advise what the normal running temperature is for the 49 p3 75 give or take a little for different outside temperature is. mine pushes up towards 100 degrees C on normal high way driving about 80 MPH but when i stop and check it does not seem to be overly hot. i am not sure if the gauge is telling me porkies or i have another issue. has any body had a similar problem and what action did you take to rectify this. regards Derrick Smith.

[deckell]

On my previous post i stated 80MPH i should have said 50MPH sorry for the miss information. regards Derrick.Smith.

[Chris C]

Hi Derrick, My P3/75 (1949) normally runs at about 85deg when driving @ around 50mph (80kph).

Have you changed anything on your cooling system, is the thermostat working correctly ?
You could take the thermostat out and test it in a pan of very hot water and with a thermometer
see what temperature it opens and will it fully open.

Does it have the correct thermostat fitted ?? A normal single opening thermostat doesn't
allow the cooling system to work correctly and may cause the engine to overheat.
You need a double valve thermostat for this engine, as when it opens up the main flow
of the cooling system, another plate closes off the bypass port. ( or that's how it looks as
though it works).

http://upload.wikimedia.org/wikipedia/c ... mostat.jpg

Hope this helps, Chris C.

[deckell]

Thanks chris for your advice,i have changed the thermostat which was 75 and put a 71 degrees in but made little difference i find when going up a rise the temperature increases very quickly.i have taken the radiator out today after i had it checked with an ultra violet light temperature sensor which showed a blocked radiator. that`s what they tell me so i hope they are on the right track.taking the radiator out was the last thing i needed.thanks again. regards Derrick.Smith ps i will let you know the result.

[deckell]

Hello chris i have had the radiator cleaned out but very little rubbish was found, i am in the process of replacing it at the moment.i meant to ask you if you have your fan cowling attached as mine is missing,do you think this could be the cause of the problem.thanks again regards Derrick.Smith

[Chris C]

Hi,
Sorry to hear that you still have a problem, no I haven't got a fan cowl on my car.
But temperatures here in the UK are normally less than in Australia.

Is the actual temp gauge on the dash OK.

Rgds, Chris C

[lakesrally]

Did you have the radiator thermal pattern checked again after it was cleaned out? In my experience unblocking the radiator rarely works, the only solution is to put a new core in it. Just be grateful it is not a honeycomb!

[rover1955]

Hello ,
I have found that the P3 75 engine is not liable to overheat. A temperature of 85 degrees is perfectly OK. In fact on a hot Summers day driving( with the wind)mine reaches 90 degrees
which is what modern cars run at. The time to worry is when you see clouds of steam coming out of everywhere.In fact , if your car reaches 90 degrees ,it is going to be more efficient,
I have fitted an 85 degree thermostat, and am thinking about a 94 degree one. Remember, this car/ engine was built to be operational in the hottest parts of the Empire.
Cheers, Robert

[Freewheel]

Often the P3 overheating /cooling issue is due to the alloy elbow return at the bottom corner becoming corroded and furred up.
- this might be reducing the return flow ... and reducing flow through the radiator matrix.

Meanwhile if there's a problem, being a non-pressurised system a little boiling of the heat soak never hurts ...

Picture here bottom left, return elbow to bottom hose just in view: -

[deckell]

Thanks for your information paul i have now had the radiator completely stripped and the elbow is fine but a third of the tubes in the core are blocked.so i have decided to go for a new core, if that does not eliminate the problem i will have to look further afield.regards Derrick.Smith