Sidevalve thermostat, does it need one?

[WPR678B]

I think this topic has been discussed before, but i can't find the thread!
In the later type sidevalve engines with the thermostat housings, how important is it to fit one?
The reason i ask is that i am running a later type engine in a lowlight and it has the housing to fit one, but i do not have a waterpump fitted. On the original lowlight head there was no place to fit one and i am wondering that as i don't have a waterpump fitted should i be running with or without the thermostat?
I am working on the theory that without the waterpump in place then the engine should go back to the original spec of no thermostat.
Can anyone advise me on this from experience please?

[mike.perry]

You don't need a thermostat in the later engine without a water pump but it will run quite happily with one providing the waterways in the block are clear. It will of course warm up quicker, but overheating should not be a problem. The main concern is the condition of the alloy thermostat housing.
Been there, seen it, done it!!!, even run it without fan blades.

[WPR678B]

Thanks for your reply Mike. The waterways are clear (they were previously blocked!) and the housing is in reasonable condition but i think going on what you say from experience that i will run without a thermostat and see how it goes!