Proper gaskets for aluminum thermstat housing?

[dwvcfii]

I'm about to install an aluminum thermostat housing on my E36 to replace the OE plastic one.

I ordered the AL part from Zionsville and they provided only the "profile" gasket, the oblong o-ring like gasket that fits into a recess machined into the housing. I also have the o-ring for the thermostat. Are these two gaskets the only ones I need to seal this assembly?

Reason I ask is because one of the DIYs (bimmerdiy) suggested that he was provided both the profile gasket and a flat gasket that is the shape of the mounting flange on the housing -- and he installed both of them.

realoem shows the flat gasket as an alternative to the profile gasket and does not provide a part number because it's N/A for my car's VIN (or even tons of older cars I looked at back to 1994 or so).

Thanks for any help,

-Doug

[Hellrot318is]

I would use a FAIR & THIN amount of sensor safe RTV silicone since realoem does not list a flat gasket in addition to your new gaskets that came with it and you should be ok.

[DeM3n]

I just used what it came with (that oblong gasket you're talking about) and the O-ring for the thermostat. No problems here.

[bmwdirtracer]

The two rubber pieces you have are all that is needed. If there are corrosion pits, a very thin skin of silicone can be used.

[dwvcfii]

Unfortunately, since I was under time pressure to get this done today and was not in the mood to do the job twice to fix a possible screw-up, I wound up buying an OE housing and installing that instead.

For anyone searching for this topic in the future, I'll point out that the reason why BMW doesn't provide a flat gasket anymore is because they have bonded a very thin paper-like sealing substance to the flange of the currently-available plastic housings.

This proves that BMW believes the flanges must be sealed to the block in some way. My guess is this prevents the few drips of coolant that might make it out of the gap, if any, between the rear face of the thermostat and the mating section in the block. The o-ring should indeed seal the thermostat to the housing and the profile gasket should effectively seal that side of the housing to the block.

This seems to confirm the comments that a thin film of RTV is required to install the metal housings, but based on the bimmerdiy article some vendors provide both the profile gasket and a flat gasket and based on feedback from the author of that DIY it is apparently safe to install both.

Thanks to all who responded. Would have posed the question last night but the forum was down...again.

-Doug