918cc radiator.

[yme402]

Hello
I have a 1952 mm
I have had the radiator brazed and pressure checked, and all is now fine after a coolant leak.
My question is regarding the header tank. If i leave the engine idling from cold for about 20 minutes, the header tank will become too hot to touch - is this normal?
Also, i am hearing bubbling noises from around the cap, however no liquid is emerging, and also when i press down on the cap, the noise ends - is this something to be concerned about?

Many thanks

[karlcouchMM1952]

Hi,

My header tank gets really hot as well. I dont think you should be concerned.

However, you might consider changing the radiator cap though if you can hear air escaping.

Best of luck,

Karl. (South Wales Branch - Series MM 1952)

[RobThomas]

IIRC, the cap is rated at 4psi so when it heats up and the air expands it will pop off at 4psi to keep the rad from bursting.

Do you have a fan on the dynamo or a waterpump?

[yme402]

Thanks for this Karl.
I will try and source a new cap. It is not the original radiator, but one that looks circa 1960s (marston)

Cheers

Tony

[yme402]

Thanks Rob.
There is no water pump - just a fan.

[mike.perry]

Have you got a thermostat fitted?
Is the bottom of the rad cold?
It is probably not a good idea to leave the engine running at tickover for a long period as the fan will not be drawing much air through the rad, particularly on a hot?? day. Having said that I have run my engine without water pump or fan for a two week period without it overheating. However I did have a temp gauge

[yme402]

Hi Mike
No water pump.
How can i tell if I have a thermostat ie. where is it located, and what does it look like?

[mike.perry]

The thermostat is under the thermostat housing at the end of the top hose.

[karlcouchMM1952]

Hi Tony,

My sidevalve doesnt have a water pump either, I also dont have a temp gauge. It is a bit of a worry on really hot days but saying that the bottom hose always seems to be quite cool. Only on really hot days do I think about it really. Maybe you could get a temp gauge fitted if your worried? It would give you peace of mind.

Karl.

[mike.perry]

Next question will be "Where do I fit a temp gauge sensor?"
If anyone wants to know just ask

[yme402]

Hi Mike
Yes - that would be useful to know.

[mike.perry]

The sensor can be mounted as low as possible in the radiator header tank, the one in the photo is too high[frame][/frame]
Or on the later heads the circular boss in the head, adjacent to no 3 spark plug can be drilled and tapped
[frame][/frame]
The Smiths Gauges are available with a magnolia face which matches the existing gauges and electric or capillary
[frame][/frame]