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Old 04-21-2009, 02:40 AM   #4
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Join Date: Jan 2006
Location: Cyprus
Posts: 6,551
My Ride: ESS TS2 320ci
Originally Posted by bmwbun View Post
The Bentley manual describes draining the coolant first.

It also explains that the wires inside the thermostat are actually heaters. They go on to explain their purpose and function.

Good reading to do before undertaking this repair.

Not sure I would have applied the orange goo...

Yes, they heat up an element inside the t-stat to open it under heavy load conditions where the coolant around the cylinders would boil before a conventional t-stat would open. It says to drain the coolant to prevent leaking on the belts etc. Good thing to do if you don't plan to clean the mess afterwards. I used a good engine cleaner and after everything dried, some baby powder on the belts. When sprayed with coolant and not cleaned, the belt will slip.

Originally Posted by grafiksguy View Post
Overall a good DIY, particularly the pix. That said, I'm also not sure I'd go with the silicone sealant on the face of the block. The gasket does the job just fine when properly torqued and when you need to remove the T-stat again it's going to be much more messy to do.
I wasn't sure either if I would use silicone gasket sealant, but apparently the gasket doesn't do it's job properly BMW used a very thin piece of rubber gasket which does wear out even if properly torqued. The silicone gasket sealant sticks on the engine block but not on the composite material of the t-stat so if you ever need to remove the t-stat you just pull it out, and use a scrapper to remove silicone from the engine. I used this silicone gasket in numerous applications such as my valve cover gasket, oil pan (in another car) etc. Better to take an extra hour scrapping silicone from the engine block rather than having coolant leak on the engine/belts.

Thanks for the comments
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