Overheating

[Thowdfella]

My 1966 122s has shown on the temperature gauge as being too hot ever since I got it.
This is what I have done.
Replaced thermostat and all hose pipes
Had new core fitted in radiator and new cap.
Removed water pump and checked and looks ok
Removed cylinder head and had unleaded conversion and overhauled.
Flushed engine with hose pipe and also with cleaning fluid.
I thought it must be the thermal sensor to the temperature gauge so replaced it with an electrical one and a new gauge. This now shows 120 degrees - far too hot!
So what can it be?
I have ordered a new water pump as I believe these have quite critical tolerances but if that doesn't fix it I am Stumped.
Please read what I have done before commenting. Thanks

[grantbennett2]

could it be the actual gauge? the new one. Is water flowing through the rad?

[old fart]

How can it be 120 degrees when water boils at 100?

[JP 1800]

Water at 1 Atmosphere boils at 100 degrees Celsius however at increased pressure the boiling point also increases. But pedantry aside the 120 degree is obliviousy not correct. I think the 66 amazon has an open cooling system so not pressurised. Take the new temp sensor and test it in boiling water to see if it shows 100C, also ensure that you bleed all the air out of the system, this will require jacking the front of the car up so all the air can bleed.

[Ron Kwas]

Tf; It sounds like you have done a lot of the right things, but I must ask, can you trust the messenger? Have you verified accuracy of the Temp indicating system? See: http://www.sw-em.com/temperature_gau...__are_you_sure

OF; JP has it right! Cooling Sys is under a few PSI of pressure, which is determined by Pressure Cap, and which raises the BP!

JP; You are calling a Cooling System without Expansion Bottle "open" and wrongfully thinking it is not pressurized...it is most certainly also under pressure with the Pressure Cap is located on Radiator, not on the Exp Tank as with the later Systems. See: http://www.sw-em.com/Cooling_System....cooling_system

Cheers

[Thowdfella]

Thanks for the replies. Yes water is flowing through the radiator after the thermostat opens. its hot at the top and cools nicely as you feel lower down and very cool at the bottom. I will check the sender in boiling water today, but can you tell me how to bleed the system? incidentally, the heater is churning out hot air so no air in there.

[Uncle Benz]

Daft question, you have got a fan fitted, either a mechanical one on the water pump pulley, or an electrical one on the radiator if someone has modified it?

[arcturus]

Originally Posted by Thowdfella

Thanks for the replies. Yes water is flowing through the radiator after the thermostat opens. its hot at the top and cools nicely as you feel lower down and very cool at the bottom. I will check the sender in boiling water today, but can you tell me how to bleed the system? incidentally, the heater is churning out hot air so no air in there.

Which ever way you bleed the air make sure the heater is fully open.

[Thowdfella]

Having read Rons very informative article complete with diagrams I have done the following. Put the original thermal sensor in boiling water and it goes across to the H Mark which is just a bit short of 100 degrees on Rons picture.
My thermostat is 82degrees when it opens and again Rons pic shows that as being over the half way mark so perhaps my engine is not overheating.
Incidentally the brand new electrical sensor when put in boiling water read122 degrees on the brand new gauge so crap but which one - the sensor or the gauge?!!!

[arcturus]

Sensors are fairly inexpensive.Try a different one.