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Old 06-14-2018, 03:27 PM   #1
bmWes
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what rating thermostat?

I have a 91' 325i. I have gone on multiple websites and they all display 71, 75, and 80 degrees C rating thermostats but I cant seem to find which one exactly goes to my car? Can anyone help?
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Old 06-14-2018, 03:35 PM   #2
e30strokr
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from bimmerworld

"BMW used the same design of thermostat for many models from the 1980s-1990s but with different temperature ratings. This is the 80C degree thermostat (in the middle of the temp scale). 80C was standard on E30 325e/325i, E28 528e/535i, E34 525i M20, E34 535i, E24 635CSi, and E32 735i. Thermostats are interchangeable among the models listed below but note that using a non-standard thermostat will alter your engine's performance. On other models this may be a Performance thermostat used with engine fan delete kits."

I don't think you will ever see a "higher temperature" T-stat than the standard.. only cooler
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Old 06-14-2018, 03:41 PM   #3
bmWes
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Quote:
Originally Posted by e30strokr View Post
from bimmerworld

"BMW used the same design of thermostat for many models from the 1980s-1990s but with different temperature ratings. This is the 80C degree thermostat (in the middle of the temp scale). 80C was standard on E30 325e/325i, E28 528e/535i, E34 525i M20, E34 535i, E24 635CSi, and E32 735i. Thermostats are interchangeable among the models listed below but note that using a non-standard thermostat will alter your engine's performance. On other models this may be a Performance thermostat used with engine fan delete kits."

I don't think you will ever see a "higher temperature" T-stat than the standard.. only cooler
Thanks for the info
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Old 06-14-2018, 04:14 PM   #4
e30davie
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I understand the thermostat was specd for your climate so its dependant on ambient temp.

Have a look on Real oem with your vin number.

for what its worth there wasa 75 degree one in my M20, and i put in an 82deg one as its what was in stock at the shop. Water temp gauge now says 82deg in stead of 75deg. So no real difference...

Hotter engines are more efficient. some of the "performance" thermostats get up to 90deg+. Im not sure if i would ever put a hotter thermostat in in the name of "performance"
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Old 06-14-2018, 05:04 PM   #5
ForcedFirebird
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Thermostat should match the thermal resistor in the radiator. If you put a lower temp t-stat in your hoses, the electric fan won't turn on. The e36 318ti has an 80c thermal switch in it. Threads right into your radiator.

In the end, the m20 makes the most power at ~92c
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Old 06-18-2018, 07:19 AM   #6
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The temperature rating is when the thermostat starts to open, so the engine will run a bit hotter than that. A hotter thermostat will make warm up time shorter as it opens later. Usually you would use a hotter thermostat in colder climates to allow the engine to warm up more before the cooling system starts to work.
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