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Discussion Starter #1 (Edited)
So I decided to change my thermostat to be prepared for the upcoming winter season. After reading about all the headaches with the o-rings, I ordered a couple extra of each (for a total of 10) and picked them up at the dealer along with a couple jugs of BMW coolant. The charge for the o-rings was about $88! I just about pooped my pants. $172 in total for two jugs of coolant, an oil filter, and these stupid o-rings.

Anyways, I decided to dig in tonight, and wanted to take the plenum off to make things "easier". I thought, what the heck, I've never had it off, and I wanted to have a look-see at those throttle bodies - maybe give them and the ICV a clean. The thermostat replacement went fine, and I did do a little seafoam into the throttle bodies while it was apart. No leaks with from the cooling system, so it's time to button it back up - but the oil separators did not want to go into the plenum. I lubed them, but one ripped as I was pushing it into the plenum. I'm assuming that you put the grommet on the separator 1st, then push the assembly into the plenum - given that that's the way it came out. I didn't have the plenum bolted down, to give me some wiggle room. What's the trick? I haven't read about anyone else having this issue, and some people even take these things out annually to clean them. Please don't tell me the grommet goes into the plenum 1st!

No driving for me until these stupid grommets come in. I'll bet the dealer charges me a fortune for them (I better order two). There are times I wish I lived elsewhere... buying parts from the US usually makes sense financially, but it takes too long for stuff to arrive. $88 for o-rings!!! What a load of crap! grrrrrrr

Any tips on the oil separator reinstallation would be appreciated (asking this after having no trouble with the t-stat!).
My thanks!
 

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Mine came out fine. I replaced mine but cleaned it once before, i never replaced the grommet either times. I left the grommet in the plenum, and used silicone spray to lubricate the oil seperator before inserting it into the plenum. Becareful on the type of lubricant you use, It might not be a big deal on those type of o-rings but i know certain petroleum based lubricants will cause some rubbers to swell and deteiorate. (white lithium grease/wheel bearing grease)

I just slipped on the bottom hose, tighted it down then forced it into the plenum. I do have smaller hands which helped too.
 

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Discussion Starter #3
Thanks for the reply. I'll bet the grommets were deteriorated from the oil misting. I'll try the new ones with the grommets put in the plenum 1st, then inserting the separators. (when they get here)!
 

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Grommets should go into the plenum first and then the oil separators follow. I typically use a little bit of petroleum jelly to lubricate these types of items and have found that it doesn't have any negative long-term effects. It is oil-based and can cause degradation of rubber, but isn't solvent based like a lot of automotive lubricants.

Did you replace the lower hoses from the separators to the sump as well as the plenum drain hose?
 

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Discussion Starter #5
Grommets should go into the plenum first and then the oil separators follow. I typically use a little bit of petroleum jelly to lubricate these types of items and have found that it doesn't have any negative long-term effects. It is oil-based and can cause degradation of rubber, but isn't solvent based like a lot of automotive lubricants.

Did you replace the lower hoses from the separators to the sump as well as the plenum drain hose?
Thanks for the instructions AMP. I figured I'd put them in the same way they came out (on the separators), which I know I read on an older thread was the order of assembly. I should have asked, instead of searched... I didn't recognize the author of the advice to do it the other (wrong) way. Such a simple thing - I'm embarrassed to have had a problem with this.

The original lower hoses were still stiff, so no, I didn't replace them. I was thinking about it though, and did ask the parts counter about availability today while I was ordering the new grommets for $32 each for Tuesday a.m., and it was going to take 2 weeks± for the lower hoses, so I figured I'd take my chances on keeping the originals in place, and pray it doesn't bite me in the near future...

Actually, everything looked pretty good under there. I was expecting to find at least some crumbly bits. Actually doesn't seem to be too bad to get access to that stuff, in comparison to removing the intake on my 540. I'd much rather pull the plenum on the M5.

Cheers,
Jeff
 

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Thanks for the instructions AMP. I figured I'd put them in the same way they came out (on the separators), which I know I read on an older thread was the order of assembly. I should have asked, instead of searched... I didn't recognize the author of the advice to do it the other (wrong) way. Such a simple thing - I'm embarrassed to have had a problem with this.
On these there's no right or wrong way... well I guess there's always a wrong way...

I've found on these that the outer ridges on the grommet make installation more difficult if there isn't some give in the center. I'm honestly surprised that they came out intact as I usually end up shredding them in getting them out. They must be a bit squishy.
 
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