E34 M50 thermostat (75 vs 88 Celsius) experience

[ktteoh]

folks, i like to know if anyone has run a lower temp thermostat i.e. 75 degrees Celsius vs the normal 88 degree version.

is it better for engine parts as the heat stress is less?

i'm looking at an ebay item but the brandname is wahler which i'm not familiar with - any opinions on this brand?

http://cgi.ebay.com/ebaymotors/BMW-7...spagenameZWD1V

[632 Regal]

you will get more wear with a cooler stat, your engine was designed for the proper temperature.

[pingu]

And you'll probably lose some fuel efficiency too.

[SnakeyesTx]

HUGE misconception on lower temperature thermostats.

Lower the number doesn't mean cooler running. It means it opens at a lower temperature. When it does that, the coolant in the radiator doesn't get as much time to cool off since its constantly cycling with the thermostat opening more often. Inevidably, you're going to end up running hotter than normal since the coolant has less time to cool down in the radiator.

Stick with what it came with. If you want to run a little cooler, run Red Line's Water Wetter or Royal Purple's Purple Ice. Those actually work. (in my case about 10-15 degrees difference on my old big blocks) Your results may vary a little depending on geography, and engine and driving behavior.

[yaofeng]

HUGE misconception on lower temperature thermostats.

Lower the number doesn't mean cooler running. It means it opens at a lower temperature. When it does that, the coolant in the radiator doesn't get as much time to cool off since its constantly cycling with the thermostat opening more often. Inevidably, you're going to end up running hotter than normal since the coolant has less time to cool down in the radiator.

Stick with what it came with. If you want to run a little cooler, run Red Line's Water Wetter or Royal Purple's Purple Ice. Those actually work. (in my case about 10-15 degrees difference on my old big blocks) Your results may vary a little depending on geography, and engine and driving behavior.

This runs againt experience and also physics. Let's say you remove the thermostat so there is an open hole on the extreme side. Your engine will be running very cool because more coolant is now flowing through the radiator.

Do you have a car, any car, with a stuck open thermostat? The car will be running very cool. Cool to the point you won't get heat in the cabin during winter time in some cases.

[SnakeyesTx]

Have you ever crept along on a 130+ degree beach at less than 5 mph in 4-wheel low with no thermostat? Sure it runs initally cool for a while, but the coolant is constantly moving and never has enough time to sit in the radiator to cool down and cycle through the block. Inevidably you overheat.

That's exactly what a thermostat wsa designed for. To contain the water in the radiator long enough to cool off, and to open when the water in the block exceeds the rating given to open. Without it, it just cycles until it eventually overheats. Maybe if you're driving short distances or moving all the time to have air passover the radiator a lot this would negate overheating, but the fact of the matter is, that with no delay for cooling, it never gets a chance to dissipate the heat.

[yaofeng]

Have you ever crept along on a 130+ degree beach at less than 5 mph in 4-wheel low with no thermostat? Sure it runs initally cool for a while, but the coolant is constantly moving and never has enough time to sit in the radiator to cool down and cycle through the block. Inevidably you overheat.

That's exactly what a thermostat wsa designed for. To contain the water in the radiator long enough to cool off, and to open when the water in the block exceeds the rating given to open. Without it, it just cycles until it eventually overheats. Maybe if you're driving short distances or moving all the time to have air passover the radiator a lot this would negate overheating, but the fact of the matter is, that with no delay for cooling, it never gets a chance to dissipate the heat.

Just look at what you are saying. You are suggesting (no you are saying) a cooler thermostat will make the engine run hotter eventually. Do you really believe that? If that is true, the thermostat manufacturer will be sued to bankruptcy.

We all know cooler thermostat opens earlier to allow more coolant flow at lower temperature to the radiator, thus making the engine run cooler. -30degree F ambient or 130 degree F ambient doesn't make a difference. The heat produced by the pistons will make the coolant much hotter.

[gmannino]

I've heard a technique is also to drill a small hole in the thurmostat. What is this used for and what are its benefits

[Blitzkrieg Bob]

when you bleed the system.

[tdgard]

I could give you my current thermostat. It stuck open about 2 weeks ago. Have not left the blue except when sitting on the highway--then it gets to the first mark--barely. As for this overheating muck--all I can say is my commute is 38 miles each way into the heart of downtown Atlanta. 1 to 1.5 hours each way every day--sure have not seen these supersaturated temps though.