Thread: Do I still need a thermostat with an electric fan?

The thermostat does more than just allowing the engine to warm up. Its designed to keep the engine at a relatively constant temperature.
Its a variable valve - not just open/closed, so once the engine is up to operating temperature it starts to open, but only opens enough to allow sufficient coolant flow to maintain that temperature.

The reasons that people remove them on old cars are mainly:
- they cant be bothered spending money on a new thermostat
- their cooling system is stuffed and removing the thermostat is a quick way of disguising that for a while.

If you've got a good cooling system and remove the thermostat the engine will likely never get up to correct operating temp. Fuel economy will be poor, and you'll likely start to build up condensation inside the motor etc.

Steve

It depends on the condition of the engine and the cooling system.The thermostat also acts as a restriction.Sometimes,without one, the water rushes through the radiator too quickly and doesn't get a chance to cool down.(first hand experience )
I would try it both ways and see which way the engine runs cooler. W.

Normally when driving on the road, most of the cooling air that flows through the radiator doesn't need the fan. At normal speeds, the fan contributes less than the natural air flow, so getting rid of the fan makes little difference to whether you need a thermostat. In any case as others have said, the thermostat does more than help the engine warm up quickly.

Years ago a mate of mine removed all the blades from the fan on his Peugeot 403. The water pump still circulated the water. He ran it like that for a few years because he got a couple of extra mpg and the only time it even looked like getting above normal operating temperature was driving in city traffic.

Getting rid of the fan is not a reason to get rid of the thermostat.

You need the thermostat because without it the coolant won't go around the motor,it will go through the bypass and boil the engine. Pat

Having had plenty of experience modifying and just general wear and tear maintinence on the trusty 186 i would say NEVER RUN IT WITHOUT A THERMOSTAT.
The thermostat regulates the temp in the engine, running your engine without it will cause it to run at different temps from #1 piston back to #6 piston in the end causing catastrophic faliure of the #6 piston due to never getting to true running temp on cold days and over heating on hot days. The thermo fan is only used to cool the water in the radiator when the temp switch says so... Simple answer fit a new thermostat id say a 180deg depending on the airflow you have through the rad otherwise a 190deg should be fine unless ambient outside temp is above 40 for days on end.
Great strong engine and they sound awesome with a good flowing exhaust (Old Holden man at heart)

Originally Posted by pfillery

Simple question, car is running a 186 motor but the answer should be the same no matter what engine it is. If the idea of the thermostat is to stop the water flowing to the radiator until the engine warms up (for engines originally fitted with a constant running fan) then is there a reason to have one where the cooling fan is on a thermo switch and only kicks in when the water reaches the right temperature?

i know a lot of people take out the thermostat in older cars, so is there a compelling reason to keep it in there? I am doing a flush of my coolant on the weekend and it would be easier to do it then if it can and should be done.

Originally Posted by B.S.F.Nut

It depends on the condition of the engine and the cooling system..

Not really. The cooling system was designed to run with a thermostat. Ergo, you should always use one.

I ran my Leyland V8 for a while without the thermostat and it use to over heat! that all went away when it was fitted. I assume the water was passing through the radiator so fast it didn't have time to cool down.