At this point I have now changed an oil filter housing gasket on both an E36 325i and M3, however as you can see from the parts fitment of this gasket, it will be very similar on all M50,M52,M54, S50, S52 and S54 motors. Photos will be from an M50 and S50 motors, and you may have a few additional wires or hoses to deal with on the newer motors, but the heart of this DIY remains the same. Since you will be disconnecting the alternator MAKE SURE TO DISCONNECT THE BATTERY.
- Oil Filter Housing Gasket
- 2-4 Vanos Line crush washers* 2 washers if you only want to disconnect one end of the line, 4 if you are replacing the VANOS line
- This is a good opportunity to replace your VANOS oil line as well if it is old*
- Since you have to at least loosen it, why not change your accessory belt and AC belt.
*For early E36 325i models without VANOS this isn’t necessary obviously
- 19MM Box wrench (hard to use a socket on the VANOS line)
- 10MM socket
- 13MM socket
- 16MM socket
- Socket Wrench
- T50 Torx to release the belt tensioner
M50 Accessory and AC belts
Apparently, BMW, in a ploy to make this as hard as possible (or maybe it was efficient German Engineering, you choose) made the oil filter housing also serve as the mounting bracket for the power steering pump and alternator. Consequently, you have to unbolt both of those, which means you have to take off the main accessory belt. As you can see in the photo above (which was only possible since I blew that engine and am pulling it from the car) that accessory belt is actually behind the air conditioning compressor belt, so if you want to take it all the way off, you need to pull off the AC belt first. My accessory belt was still pretty new, so I left the AC belt on and just let the accessory belt hang there. I have numbered the below copy of that photo to match my steps I have listed next.
Step 0 – DISCONNECT THE BATTERY! (Yes I already said it, but it is important)
1. Insert the T50 torx into the center of this pulley (it might have a plastic cap to pull off first) and push in a clockwise motion with the wrench at about 4-5 o-clock so you are pushing down-left. This will release the tension on the belt so you can pull it off the tensioner. Once it is off the tensioner, pull it off the rest of the pulleys
2. Remove the two 16MM bolts that hold the alternator to the oil filter housing. The lower has a 17MM nut on the back-side of the alternator that you need to reach down to with a box wrench to hold in place. It is tight. Once the alternator is loose, rotate it around a bit so you can get to the wires on the back and unbolt and remove those. The positive and negative terminals are different sizes so you don’t have to worry about mixing them up during re-assembly.
3. Remove the two 13MM bolts holding the power steering pump in place. There is one more bolt that attaches it to the oil pan so it isn’t going to fall on you but be careful as you remove those two bolts to make sure that other one is still attached. Remember, this is still attached to the power steering system as well.
Ok, now you are ready to tackle the main event….which is less eventful than the starting work.
4. RECOMMENDED – Remove the oil filter to let the oil mostly drain into the pan
5. Remove the air filter box (two 10MM bolts and the clips to the MAF and you can pull it right out)
6. Disconnect the oil pressure sensor to the back of the oil filter housing. Squeeze down on the wire sticking up from the clip and pull.
7. Disconnect the VANOS line from the front of the engine by using the 19MM box wrench to back out the banjo bolt. The other end is attached to the oil filter housing and will come out with it.
8. Remove the six bolts 13MM that hold the oil filter housing in place. They are different lengths, so remember which holes they came out of.
9. Deal with the mess that is your engine block now!
Now that your engine is the oily mess pictured above, this is a great chance to clean as much gunk off the block as possible (so it is easier to spot any leaks, new or otherwise, after everything is put back together. I would recommend shoving a rag in the openings from the oil filter housing so nothing can fall down in there if you are cleaning up the engine. This motor had 220,000 miles on it. Unfortunately, right after I did all this work I blew a head gasket on track, but at least I would have been able to spot any leaks if the engine stuck around longer. You can also see there are two pins sticking out that go into the oil filter housing when you are putting things back together to make life easier. Ok, back to the boring list of things to do!
10. Swap out the oil filter housing gasket, lube it up with just a tiny bit of oil so it doesn’t pinch during re-assembly.
11. If you are changing the VANOS line, swap the lines on the oil filter housing, using new crash washers on each side of the line when you put in the banjo bolt, but don’t tighten it all the way because it might not be lined up perfect yet.
12. Put the oil filter housing back in place and get those six 13MM bolts back in place. I hope you remembered which went where!
13. Using the new crush washers, re-attach the VANOS line to the front of the engine. Snug the front down, and if you had replaced the line, snug the back down too (it is a tight place to work though). Since I didn’t have a snow-balls chance of getting a torque wrench on either bolt, I didn’t even look up torque specs, just make sure they are good and snug, but don’t go all Hulk on them.
14. Re-attach the oil pressure sensor wire.
15. Bolt the power steering pump back to the oil filter housing.
16. Reattach the power leads to the alternator
17. bolt the alternator back on to the oil filter housing
18. Run the accessory belt over every belt except the tensioner
19. Get the belt around most of the pulleys and then pull the tensioner so you can get it around the rest of the pulleys or the tensioner.
20. Reconnect your battery
21. Crack open a cool beverage of your choice!
Like I said, I have done this all on an M50 motor and an S50 motor, but the M52 and M54 based engines should be very similar. Yes this was much longer than my other DIY, but you can thank BMW for that. I almost feel like there are fewer steps pulling the whole engine…which I unfortunately have to do this week as well…but it is a fairly simple process and is a great confidence builder for tackling larger jobs. It is also a great time to do things like power steering lines, and water pumps since you have so much stuff out of the way to do this DIY.