Since I could not find a thread anywhere describing how to merely check the supercharger oil without removing the SC, I would like to share what I learned and the resources I used to check the oil - all together in one neat little package.

The reason I decided to check the oil was that my MCS had 90k miles and it is well known that the M45 Eaton SC on the Mini has a common failure mode around 100k miles where the sealing around the waterpump (WP) gears goes bad. The resulting leak allows the secondary reservoir oil into the air intake path where it is hidden from view and, only when the gears are already damaged and making noise, will the leak be discovered. (This failure actually does nothing to the supercharging function of the M45 but of course will take the car out of service due to overheating.)

I already had to change out the upper engine mount, serpentine belt, and coolant anyway so I decided to do the SC oil check for good measure as well. I found topics online that showed how to remove the SC, but it appeared I could do the job with less work if the SC were left in place. That proved to be the case and here is how I did it.

First, I read a bunch of related how-tos on the internet to make sure I had all the tools and skills to tackle this. The good news is that I did not have to buy any new tools. I would have preferred using a 3/8" drive allen key socket for both 3/16" oil fill ports in the SC, but could only fit the regular L-shaped allen wrench into the clearance beside the secondary oil reservoir port. I did have to buy three big hose clamps for reassembling air hoses without the (ridiculously expensive) BMW clamp tool.

We begin the disassembly using the Pelican Tech guide on bumper removal:
http://www.pelicanparts.com/techarti...er_Removal.htm
The things I did differently: jacked up the whole car (4 jack stands) and left the crush tubes in place (skipped the last paragraph).

Next is removal of the air filter housing (aka airbox) using another Pelican guide:
http://www.pelicanparts.com/techarti...ake_System.htm
Stopped after Figure 11 and did not disconnect the battery.

Follow that by draining coolant using this Pelican guide (which has some mismatched figure names but it is easy enough to figure it out in spite of this):
http://www.pelicanparts.com/techarti...ant_Change.htm
I have worked on BMW products before so I chose to not touch the AC condenser at all (just left it attached to the rad). I elected not to buy extra long bolts to support the rad by sliding it forward either. I did also remove both radiator hoses completely (to give clearance for opening SC secondary oil port).

Quoted *with mods* from another Pelican guide:
"Next place a floor jack with a block of wood under the center of the engine. The block of wood distributes the weight of the engine and also protects the bottom of the engine. Take up the weight of the engine with the floor jack. Now, loosen the long 16mm bolt that secures the rubber transmission mount to the Bracket on the driver’s side of the engine compartment.

Now, go back under the engine and remove the 16mm bolt securing the lower front engine mount to the engine. Now, look at the front of the engine where the *upper* radiator hose runs just under the intercooler and *double check that you did already* remove the clamp holding the hose in place.

On 2004 and later MINIs the engine mount was re-designed so you only have to remove *the top nut, 16mm iirc* to free the mount. *(then you can skip the rest of this paragraph) But if pre 2004 model,* remove the upper passenger mount assembly by removing the nut and bolt that secures the ground cable. Next remove the 8mm bolt securing the hose bracket to the mount brace. Now remove the two 16mm bolts that secure the front mount to the mount located on the passenger side wheelhouse. Now, remove the 16mm nut securing the mount to the engine bracket."

Now you can carefully jack up the engine. (I had to replace that upper engine mount anyway, but this still serves a purpose since, when the engine tilts toward the driver side at the upper end of its travel, this will assist in checking the oil in the secondary reservoir.)

Intercooler removal. Four screws on black plastic diffuser. Two screws on each rubber boot clamp. Two bolts on each black mounting bracket such that I removed one and just loosened the other for each bracket. Remove intercooler.

Throttle body removal. Remove intake tube from between throttle body and airbox. Remove four bolts on throttle body. Remove throttle body from supercharger intake tube. No need to remove plug or small hose going to throttle body, just move it out of the way a bit.

Driver side air intake "horn" with bypass valve has three fasteners attaching it to the manifold. These are removed along with one bolt holding the black plastic SC air tube onto the SC. The air tube has two fragile vacuum line connections. The horn, bypass valve, and air tube can all be removed as a unit. But before doing so it helps to swing the radiator a bit and chock it open with a small block of wood. It behaves rather like an oven door with one really stiff hinge (on the drivers side). It is also good to make sure the vacuum lines are coming out freely. For me, this meant (for each vacuum line) my left hand with two fingers pressing the red sleeve into the SC while the right hand was pulling the line partly out. Then sliding the horn/valve/tube assembly out a bit until I relieved stress from the vacuum lines enough to remove each line completely (pulling again while pressing the red sleeve into the SC).

Photo of radiator chocked open is the first photo in the following post.

At this point, all that is left is to check the oil. In my case, that meant loosening the secondary reservoir port screw until some oil began to seep out and then immediately tightening it again. After that adjusting the jack so the engine was a bit more level and then checking the primary port reservoir the same way.

Photo of secondary reservoir port screw just after oil was checked is the second photo in the gallery below.

Reassembly is pretty straightforward as reverse of disassembly. Note that vacuum lines should smoothly insert through red sleeves into air tube with just one hand.

This write-up was done about a week after the work, so feel free to help me correct any errors or omissions.

On a side note, when my SC to WP gear seals go bad I plan to convert to an electric water pump and just eliminate the unneeded mechanical parts. I believe the M45 Supercharger probably has twice the life or more before needing a rebuild without the WP power take-off. I do not plan to remove the supercharger from the engine for a long time...

Motor On!

 

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