Engine Temperatures

[cahomey]

Is there anything strange about my car running just below the 1/4 mark and just above the blue when I'm on the freeway?
Seems like it's to cold, is there any draw backs from an engine to run at this temperature, as opposed to right in the middle?

[Jon325i]

M20s have two different thermostat sensors.....and my guess is your car has the lower of the two installed. This will have your clutch fan kicking in more frequently and thus keeping operating temps lower.

Of course, with it being November, that could have something to do with it too ;)

Jon

[MR 325]

That's way too low. You should at least rumn above a 1/4

[hamann318is]

I was running at 1/2 for a while. I blead the coolant a couple of days ago, and now I'm at a bit above 1/4.

[Jon325i]

My '89 325i (the one for sale), has seldomly exceeded the 1/2 mark on the temp guage in the 18 months I've had it.....and that includes running the A/C in stop-n-go traffic during hot Northern California summers. Its likely this car has the lower t-stat sensor.

My 'new' car, the '91 325i, seems to run at the 1/2 mark all the time. When I first got it the temp needle was flickering between 1/2 and 3/4. I bled the system to get some trapped air remove and now the temps remain consistant at the 1/2 mark. This car probably has the higher of the two t-stat sensors.

Jon

[cahomey]

That's way too low. You should at least rumn above a 1/4

Well, what are the disadvantages?
Because i can make my car run hotter.

[Kondour]

could be time for a new thermostat, car should be running just below half way.

[cahomey]

I believe it's clear where my car should be operating at.
Anyone care to elaborate on why it needs to be there?

[BS87]

My old eta never went above 1/2.

My cabrio never goes above 1/4, even when i beat the shit out of it.

[royalflush313]

I believe it's clear where my car should be operating at.
Anyone care to elaborate on why it needs to be there?

For a while I was running my car under 1/4, I replaced the thermostat and now its sitting right in the middle now. My mechanic told me that there is nothign wrong with runnign the car cold, and that it's not a huge rush to replace my thermostat - but I did it anyway because its a easy replacement - downside is not having heat and poor gas mileage.

[cahomey]

I have plenty of heat, it contributes to the such cool temperatures.
Any clue why the gas mileage drops? Or are you just relaying a delusive post you saw a while back.

[elemental]

Well I have run both the low temp and the "high" temp thermo, With the low temp my car runs at your slightly below 1/4 on the freeway, with the high temp thermo it will run at 1/2.
As far as performance, I would see it as cooler intake temp's increasing the density of the air, when i changed to the lower temp I did not notice a difference in fuel economy.

[cahomey]

I share some of your thoughts. While relative to the full range of the temperature guage, and where my engine sits is considered on the cool side. But relative to the accual temperature of the my engine, and the temperature that engines in general operate at it is still plenty warm.

So this overall lower temperature of the entire engine (including intake manifold and surrounding air) makes the consumed air cooler.

I have yet to see solid information proving that having your engine run at that temp. makes your car less efficient.

[BMW BMXER]

My car runs at 1/4 has been for a loooong time and no ill affects.

[Kondour]

this is the reason why temperature is important in an engine. too hot is bad but too cold is equally bad -Although it’s important to keep the engine from overheating, it is equally important to prevent over-cooling. Over-cooling encourages the formation of acids and sludge in the oil. It also tends to reduce combustion-chamber temperatures by quenching the flame front. This results in higher emissions and greatly reduced fuel efficiency, because much of the fuel remains unburned. That’s why it is never a good idea to substitute a thermostat with a lower opening temperature than that of the one you are replacing.