Has anyone come across a DIY to replace the two oil separators?

I wanted to replace the two oil separators (11157848155), their 2 required gaskets (11157838369, their two required O-rings (11157838370), and the 8 Torx screws (11417526315). ECS Tuning has the best price that I could find for all of the parts. My mechanic was looking over my ESS supercharged E92 M3 and noticed that the car was seeping a bit of oil out of the valve covers. He pinpointed it to the oil separators (the car has 85k miles on it) and gave me a pretty steep quote for labor and material. I priced the material out at ECS and figured that the mechanic was going to charge me $700 for labor. It seemed a bit steep especially after I had just finished helping a friend out by changing out his throttle body actuator bank 2 last weekend in a total time of 2.5 hours.

I was thinking that the supercharger's intake manifold would need to be removed to gain access to both oil separators but I wanted to find out if anyone had done this task before I start removing parts that I don't need to. Am I on the right track?

You have to remove the manifold. It's pretty damn easy after that

on my ESS supercharged E92 M3 and "damn" and "easy" are two words or adjectives that cannot be used to describe this remove and replace task. To get access to the torx bolts that hold the oil separator located on the driver's side (US version) you have to first remove the coil cover. On an ESS supercharged E9X M3, this involves removing the bolt on supercharger out of the way. There appears to be 3 hoses that are part of the supercharger configuration that will need to have their clamps and associated hoses (on the driver's side of the engine) to be removed in order to gain access to the torx bolts that hold the oil separator on to the engine. I just described an hour of prep work just for the driver's side.

As I dig further in to this task, there also appears to be some supercharger parts on the passenger side of the engine block that are not part of an OEM configuration. These parts will need to be removed prior to removing the coil cover in order to gain access to the torx bolts that hold the oil separator to the engine on the passenger side. I would estimate 30 minutes of prep work in order to eventually gain access to the passenger side's oil separator.

At this point, with the coil covers removed on both sides of the engine, I have to imagine that the removal and replace of the two oil separators and their new gaskets and O-rings should be straight forward or am I missing something?

Not sure if you're aware but the valve covers themselves are prone to warping and are usually the cause of oil leaks from the valve covers. I've not heard of just replacing the oil separators fixing this problem. Something you investigate before doing all the labor and then having to repeat it again later to replace the valve covers.

One additional point is that it is not uncommon for some of the finish on the valve cover to stay attached to the old separator. Saw a recommendation to use high temp rtv/gasket sealer when replacing.


When have you guys changed your oil separator https://www.m3post.com/forums/showthread.php?t=1332448

drrust wrote

One additional point is that it is not uncommon for some of the finish on the valve cover to stay attached to the old separator. Saw a recommendation to use high temp rtv/gasket sealer when replacing.


When have you guys changed your oil separator https://www.m3post.com/forums/showthread.php?t=1332448

Yes, I have some Permatex Ultra Gray Hi- Temp Gasket Sealant in my tool box and was thinking of using it during this installation.

im4ipsc wrote

Yes, I have some Permatex Ultra Gray Hi- Temp Gasket Sealant in my tool box and was thinking of using it during this installation.

I ended up using, per this forum's member deansbimmer a product called Reinzosil in lieu of the Permatex grey gasket maker and it worked great. Kudos to deansbimmer for this suggestion

Are the M6 aluminum Torx bolts in this application a one-time-use fastener? I have to replace a leaky O-ring on one of my oil separators, and I'm not sure if I need to replace the aluminum fasteners as well.

I planned to simply replace the bolts anyway, but the dealer didn't have them in stock (surprisingly, they had the O-rings). I'd prefer to finish this job today using the old bolts instead of ordering and waiting for new bolts. I didn't see any of the DIYs mentioning that new bolts are necessary.

Also, anyone have the torque spec for these alum bolts? The TIS torque spec page for 6mm does not have Aluminum in the list.

I reused mine though it’s not recommended. Just be very careful with the torque or you may make more work for yourself.

pbonsalb wrote

I reused mine though it’s not recommended. Just be very careful with the torque or you may make more work for yourself.

Where were you yesterday, LOL? I was tired yesterday, putting the finishing touches on a long project in a hot garage and used the wrong tool on one of these and SNAP! So I'm running on 3 bolts for the moment which I try to find a replacement.

CamasM3e93 wrote

Where were you yesterday, LOL? I was tired yesterday, putting the finishing touches on a long project in a hot garage and used the wrong tool on one of these and SNAP! So I'm running on 3 bolts for the moment which I try to find a replacement.

M6 bolts are notoriously easy to snap, and I would guess aluminum ones even more so. For the few we have going on our engine here at work (none are aluminum) the max torque is 8nm, so if you are doing it by hand that is just barely past snug. Use a long handled ratchet and you could snap one off without even putting much pressure on it.

tbuck wrote

M6 bolts are notoriously easy to snap, and I would guess aluminum ones even more so. For the few we have going on our engine here at work (none are aluminum) the max torque is 8nm, so if you are doing it by hand that is just barely past snug. Use a long handled ratchet and you could snap one off without even putting much pressure on it.

Yeah, don't I know it. I had an air tool set up to remove bolts, nuts, and screws quickly at the start of the project. As I was putting everything back together after a long day in a hot garage, I absentmindedly picked up the air tool instead of a torx screwdriver and you know the rest....

CamasM3e93 wrote

Yeah, don't I know it. I had an air tool set up to remove bolts, nuts, and screws quickly at the start of the project. As I was putting everything back together after a long day in a hot garage, I absentmindedly picked up the air tool instead of a torx screwdriver and you know the rest....

Ouch! Yeah, it happens. Were you able to back the bolt out of the VC, or have you tried yet? I can only imagine that will be very difficult to get to depending on which bolt it is. If it was one of the ones right at the o-ring seal that is going to be trouble....

tbuck wrote

Ouch! Yeah, it happens. Were you able to back the bolt out of the VC, or have you tried yet? I can only imagine that will be very difficult to get to depending on which bolt it is. If it was one of the ones right at the o-ring seal that is going to be trouble....

The one I broke is accessible. I drilled into the bolt shaft and put in my bolt extractor. When I went to back it out by hand, the extractor sheared. Sigh. Really, I'm not this strong. I'll look at it closer when I put in the Harrop next week, but for now the oil separator isn't leaking with 3 of the 4 screws so I'll probably let it be. Worst case scenario I'll have to replace that valve cover but I don't think it will come to that.

Not an ESS, but probably similar enough to at least give you a general idea of what it takes to remove the plenum and the coil covers.


Remove the cabin filter housings (3 bolts each).
Remove the cowl tray (3 bolts).
Remove the strut braces (4 fasteners each).
Unhook the blower belt.
Remove the the rubber bits to and from the intercooler.
Then off comes the blower pump (7 bolts, loosen 1 hose clamp).
Next is the airbox (6 bolts, loosen 3 hose clamps, 5 more bolts).
I remove the plenum next (remove 3 bolts, loosen the 8 ITB hose clamps, disconnect the IAT sensor, unclip a hose at the rear), and finally the coil covers.

It really is a fairly simple procedure, especially when you've done it once (or 9 times?).