thermostat

I have just installed a newish thermostat housing that came with the thermostat installed.
The engine runs much cooler now, about 70 I would guess when it used to be 85 or so. When I dismantled the old housing the thermostat was 86 degrees.
I don't know why it was fitted in the past but what is a good coolish temperature to expect on the gauge and could it be giving a false low reading?
I have bled the system and all the pipes get hot when the engine has warmed up, the heater works properly. Any ideas?

Hi David,

I have always thought that the engine should be 85-90 degrees when the cooling system is running correctly.

Theoretically if you are running at 70 degrees then the thermostat should not have opened.
The standard thermostat as originally fitted starts opening from 73 to 77 degrees.
It should be fully open at 85 degrees.

You could always try and set up a temperature probe on the engine to check the gauge is reading correctly.
I did this a few years ago on my GF as the temperature gauge was reading very high. Sadly the probe proved that the gauge was reading correctly!!

One more thought: if your new thermostat is designed to open earlier it will take the engine longer to get to normal operating temperature. have you run it long enough to prove this?

Cheers

Andy

Thanks Andy, some good ideas there especially the last one, I haven’t given it a good run as I was nervous but I will today.

Hi David,

If you are just running your car during summer months, when the ambient temperature should be higher, then theoretically you could run the car without the thermostat. It would just take longer to get to normal operating temperature.
I do think the normal operating temperature for the engine should be in the 85 - 90 degree area.

If it is consistently running hotter than the above then that would be time to service the cooling system starting with re-coring the radiator.

Cheers

Andy

I think you are right about it taking longer to get to temperature. I used to live in Western Australia and lots of cars there ran well without thermostats. We had an MGA then a Bug Eye Sprite and both ran well without one.
I think I just need to take it for a longer run which if the showers stop today, I will.