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Technical_   Engine_  Oil Pan Replacement

Changing the M20B25/B27 Oil Pan
Josh Anderson

The day I gave the 325i I bought a thorough check-over, the guy I bought it from hit a rock on his way home and tore a 2Ē x 3Ē hole in the oil pan. Needless to say, he knocked $400 off the price of the car for parts and labor to get it fixed. So instead of paying $45 to have it towed to the mechanic, $280 for a brand-new oil pan, and about $250 for labor (for a grand total of about $590), I decided to spend about $100 and a day off, get a couple of my friends together, and fix it myself. This job will take about 1-3 hours, depending on your mechanical knowledge.

Tools needed:

  • Yourself, and 1-2 mechanically competent friends
  • New oil pan
  • New oil pan gasket
  • New drain plug (optional)
  • New oil filter
  • 5 quarts of your favorite oil
  • Power drill w/ socket attachment bit
  • Sharp putty knife or gasket scraper
  • Several assorted size metric ratchets, sockets and torx sockets
  • Several assorted size metric wrenches
  • Ratchet swivel/u-joint
  • Assortment of short and long ratchet extensions
  • Engine lift
  • Floor jack
  • 2 jack stands
  • 1 case of beer (optional Ė age permitting - for afterwards)
  • An extensive vocabulary of colorful expletives

Drain ALL the oil out of your engine (unless a hole in your oil pan already did it for you). Remove the oil level sender and the ground strap from the front-top of the oil pan. It doesnít hurt to disconnect your battery before doing this, either. Remove the hood. Remove the fan shroud from the radiator.

Jack up the car on the front subframe of the car as high as is safely possible, and position the jack stands under the frame on each side of the car behind the front wheels, then remove the floor jack. Disconnect the oil cooler lines [325i models only -Fred] from where they mount to the block, near the oil filter mount. Move toward the front of the car, and unbolt the motor mounts.

There is a flywheel cover over the back of the oil pan that covers the back 3-4 inches of it. This must be removed. There are 4 bolts holding it vertically, and 4 torx bolts holding it horizontally. These must all be removed to get the small cover off. Some of them are different lengths, so make sure you remember which ones go where. Once you have all the bolts out, it takes a little reefing to get it off, but just pull down gently on the 2 steel lines running along the tranny to get it out.

Position the engine hoist at the front of the car, and secure it to the hoist point located at the front of the cylinder head. Lift the engine SLOWLY up, as high as you can safely lift the motor. THis should give you more than enough room to remove the pan and clear the oil pump without having to remove it.

There are 25 (thatís right, TWENTY-FIVE) 10mm bolts that hold the oil pan to the block. THIS is when the power drill comes in handy, or you will be under there all day. You will be able to get most of them out with the drill, but a few of them are in tight spots, so use your ratchet and extensions to get them out.

After removing the oil pan, set it aside, get on your back under the engine, get your gasket scraping implement, and remove all the remaining gasket that is still stuck to the block. Trust me, there will be a lot, and youíll probably end up eating about half of it. Be careful not to gouge the surface of the aluminum while scraping.

Position the new gasket on the oil pan, making sure that it is on correctly. The shape of the gasket surface is not symmetrical, so be sure than it is on in the right orientation. To make bolting the oil pan and gasket up to the block a little easier, you can dab a tiny amount of gasket sealant every few inches or so under the gasket to make it stick to the pan. This saves you a lot of alignment headaces.

Replace the 25 oil pan bolts, and make sure they are snug. You donít want them super-tight, just nice and snug. Replace the oil lever sender and grounding strap. Donít forget the grounding strap, or the car wonít start. Ask me how I know.

From here on out, putting everything back together is just the reverse of everything you have done up to this point. As always, be sure to check the car thoroughly for tools, and that you have EVERYTHING bolted back up nice and tight.

Good luck, and be careful. You will be under the car for most of this job.


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