As far as issues with BMW's engines go, leaky oil filter housing gaskets are as common as they get. Leaking oil filter housing gaskets date back to the E36 3-series and continue to be an issue on BMW's recent N20 and N26 engines. The rubber gasket separating the filter housing from the engine dries up from the engine's heat and begins to leak. On previous engines, that leak could lead to catastrophic belt failure. But N20/26 don't need to worry about that. However, an oil leak is nothing to put off, and you should address the issue as soon as possible.
Replacing the oil filter housing gaskets requires draining some oil and engine coolant. While you won't disassemble anything inside the engine, you'll have to remove several key components to get to the housing. Follow along with the video and the steps below to ensure that you have a properly functioning BMW after replacing the gaskets.
BMW models and years applicable:
Symptoms of a leaking BMW N20 or N26 oil filter housing gasket:
- Oil leak around the front of the engine
The oil filter housing is a common leak point on this series of BMW engines. The old gasket dries up and shrinks, allowing oil to weep past. An oil leak from the oil filter housing is a high-pressure oil leak that will negatively affect your engine's performance. If you have detected this oil leak, repair it as soon as you can.
How much will it cost to replace a BMW N20 or N26 oil filter housing gasket?
There are a few things you'll need for this DIY. First is the oil filter housing gasket kit, which will run you around $60. You need to drain the engine's cooling system to remove the housing, so a jug of coolant is required to fill it back up. For around $25, you get a gallon of non-diluted genuine BMW coolant. BMW recommends a 50/50 mix of coolant to water, so that jug should get you two gallons when diluted correctly.
You will need to drain some engine oil too. That can range from around $8 for a single liter to around $40 for enough to fill the engine. Lastly, we recommend replacing the oil filter during the job as you need to remove the old one anyway. A new filter with the appropriate o-rings will run you right around $8.
In total, expect to spend around $120 to $140 for the job. Anything left over in the budget can go to rags and brake-clean for cleaning off any oil residue on the oil filter housing and the engine.
How long will it take to replace a BMW N20 or N26 oil filter housing gasket?
You're going to need to remove the engine computer and partially remove the intake manifold just to get to the rear-most oil filter housing bolt. On top of that, you need to drain the cooling system, at least partially. Replacing the gaskets isn't very time-consuming, but the rest of the job is. With the right tools, expect the job to take a couple of hours on the safe side.
Parts required to replace a BMW N20 or N26 oil filter housing gasket:
- BMW Oil Filter Housing Gasket Kit
- Mann Oil Filter Kit (Recommended)
- BMW Coolant (1 Gallon, non-diluted)
- BMW Engine Oil
Tools required to replace a BMW N20 or N26 oil filter housing gasket:
- 8mm Socket
- 10mm Socket
- 11mm Socket
- 13mm Socket
- E10 Socket
- E12 Socket
- T30 Torx Bit Socket
- 6mm Nut Driver or Socket
- 7mm Nut Driver or Socket
- 8mm Nut Driver or Socket
- Ratchet Set
- Torque Wrench
- BMW Oil Filter Socket
Steps required to replace a BMW N20 or N26 oil filter housing gasket:
Step 1: Remove the intake and engine cover
Open the hood and examine the intake airbox. Locate the hood cable secured to the rear of the airbox cover and remove it from its clips.
Next, unplug the mass airflow sensor's electrical connection. Then, use a 6mm nut driver to loosen the hose clamp that secures the airbox to the intake tube.
After that, pull up on the airbox to remove it from the engine bay. It mounts to the car by three rubber grommets. Pop it out of the three grommets, and you can lift it out.
At this point, you will have good access to the filter housing; however, removing the lower intake tube will give you more space. To do so, use a 7mm socket or nut driver to loosen the tube's hose clamp. Pull the tube out when the clamp is loose enough.
Next, remove the engine cover. If you're BMW is pre-2013, disconnect the vacuum lines on the passenger's side of the engine cover before pulling it off. Then, pop the trunk, remove the panel on the passenger's side and disconnect the negative cable from the battery.
Step 2: Remove the DME
The intake manifold blocks the rearmost oil filter housing bolt, so you need to remove the intake manifold. But, the engine computer, or DME, is blocking the intake manifold's studs, so you need to remove the DME as well. Starting with the three plugs on the passenger's side of the DME, depress the tab with a flathead screwdriver and then slide the lock over the tab. SLiding the lock downward will push the plug out of the DME.
The remaining large plug on the right side of the DME uses a sliding lock. Grip the bottom of the plug and pull it towards the front of the engine bay. Doing so releases the lock and pushes out the plug.
Lastly, pinch the tabs on either side of the two remaining plugs and pull them out of the DME. One of the plugs has a few wires running off of it, down to a pressure sensor. Unplug that connection, too. Then, push the plugs and wires to the side.
Lastly, use a T30 to remove the DME's four mounting screws. There is one at each corner.
Step 3: Remove the charge pipe and intake manifold
The charge pipe runs along the driver's side chassis rail, from the intercooler to the throttle body. Use a flathead screwdriver to pull up on the locking rings at both connections.
Pull the pipe off at both ends but not out of the engine bay. Two vacuum lines remain connected to the bottom of the pipe. Press in the tabs on either side of the vacuum lines and disconnect them from the pipe. Pull the charge pipe after you've disconnected the vacuum lines.
Next, use an 11mm socket to remove the five nuts securing the manifold to the cylinder head. Pull the manifold away from the head after removing the nuts to reveal access to the rear oil filter housing bolt.
Step 4: Drain the coolant
The oil filter housing, at this point, still contains engine oil and coolant. Removing the housing now would result in a huge mess of fluids in the engine bay. So, sue the oil filter socket to remove the oil filter and allow the oil in the housing to drain into the engine. If you have a suction tool, you can pull out any remaining oil from the housing.
After that, loosen the coolant expansion tank's cap, allowing air to enter the system as the coolant drains. Then, jack up the front of the car and remove the splash shield. Use an 8mm socket or nut driver to remove the twenty-three bolts securing it to the bottom of the car. If your car uses xDrive, remove the reinforcement plate under the splash shield with a 13mm socket.
The water pump sits to the left of the harmonic balancer. Place a drain pan underneath the pump and then loosen the hose clamp on the water pump line with a 6mm socket or nut driver. Pull the line off and let the coolant drain.
Step 5: Remove the oil filter housing
Place the front of the vehicle back onto the ground and aim for the oil filter housing. Start with the rear-most bolt, which required you to remove the intake manifold from the cylinder head.
Use the E10 socket with an extension to reach and remove the bolt. Then, move around to the front and disconnect the two coolant lines. Use some pliers to slide back the hose clamp on the smaller coolant line running out of the oil cooler. Then pull off the hose.
After that, use a pick to unlock the larger coolant line from the housing. Wiggle that line out of the housing and push it aside.
Then, remove the final oil filter housing bolts. Use an E10 socket or wrench to remove them.
Pull the housing off once you remove the bolts.
Step 6: Replace the oil filter housing gaskets
Place the housing assembly onto a workspace and use some brake clean or degreaser to remove the oil and grime covering it. Then, use an E12 socket to remove the oil cooler's three bolts to separate it from the oil filter housing.
After that, pull out the old gaskets from the oil filter housing. Use a pick to pull out the gaskets if you need to and make sure all of the old gaskets come out. Press both of the new gaskets into the housing before resecuring the oil cooler to the housing.
Step 7: Refit the oil filter housing
Now take your freshly gasketed housing and refit it to the engine. The longest mounting bolt goes in the top location, the medium length goes in the rear under the manifold, and the shorty goes upfront. Thread in all of the bolts by hand before using an E10 socket to tighten them down.
You'll want to thread in the forward bolt first. Its proximity to a hose flange means there won't be much room to work. You're going to need to thread the bolt into the housing all the way, using the bolt to pull the housing into place.
Walk all of the bolts down evenly before using the E10 socket to torque them to 22Nm. After that, use the E12 socket to torque the oil cooler bolts to 18Nm, plus an additional 20° of rotation.
You can reuse the oil filter, but it's cheap and easy to replace while it's already out of the housing. If you aren't replacing the filter, thread it back into the housing. If you are replacing the filter, use a pick to remove the two o-rings from the cap and throw out the old filter. Replace the two o-rings included in the filter kit, and then press the new filter into the cap. After that, thread the cap into the filter housing. Use the oil filter cap socket to tighten and torque the cap to 25Nm.
Next, refit the coolant lines to the oil cooler. Push on the smaller line before using a pair of pliers to move the hose clamp back into place. Then press the upper radiator hose back into place. Lubricate the o-ring inside the hose with some coolant before wiggling and locking the hose into place. You should be able to reach the water pump hose from the top of the engine bay, too. Use a 6mm nut driver or socket to tighten that hose clamp.
Step 8: Refit the intake manifold
Pull the manifold as far as you can away from the cylinder head to remove and replace the intake manifold gaskets. Use a pick to pull the old gaskets out of the manifold.
Press the new gaskets into place before sliding the manifold back onto its studs. Then, thread on the nuts.
Start tightening at the center nut, working your way out to compress the manifold gaskets evenly. Use the 11mm socket to torque the manifolds nuts to 15Nm, again working your way outward from the center stud.
Step 9: Reinstall the charge pipe
Take the charge pipe and fit it into position in the engine bay. Lubricant the o-rings on both ends of the pipe to make the installation easier for yourself. Once both ends are fit into their respective locations, press their locking rings into place. Then, reconnect the two vacuum lines to the pipe.
Step 10: Reinstall the DME
Take the DME and fit it into position on the manifold; the bolts only align in one orientation.
Thread in its four fasteners and tighten them with a T30 Torx bit socket. Torque them to 12Nm. Then plug in all of the harness connections to the DME. Each plug will only lock into its specific position on the DME, so don't panic about not knowing which plug goes where.
After that, head back to the trunk and reconnect the ground cable to the battery. Use a 10mm socket to tighten the cable's connection.
Step 11: Refit the intake
Slide the intake tube into position and ensure it's aligned properly on its tabs. Use a 7mm nut driver or socket to tighten its hose clamp.
Once in place, resecure the coolant line to the bottom of the tube. Then, refit the intake airbox to its mounting studs. Slide the intake tube onto the airbox and then secure them together using a 6mm socket or nut driver to tighten the hose clamp.
Lastly, plug in the mass airflow sensor and refit the hood cable back into its clips on the airbox.
Step 12: Fill and bleed the cooling system
Take whatever kind of coolant you're using and fill the expansion tank with it. Then, follow these steps to bleed your cooling system. As the system bleeds, the coolant level in the expansion tank will drop. Fill the tank to its maximum cold level after the bleeding procedure has finished.
While you're there, be sure also to check the engine oil level. Top it off with oil as you see fit.
Step 13: Refit the engine cover and splash shield
Take the engine insulating foam and fix it atop the valve cover. Slide it on until it sits flush, then fit the engine cover. Slide the cover's tabs into the slots at the back of the valve cover before pressing the front of the cover into place.
If you're N20/26 uses the vacuum-operated wastegate, don't forget to reconnect the vacuum lines to your engine cover.
Refit the reinforcement plate if you're working on a vehicle with xDrive. Use a 13mm socket to tighten the eight bolts. Then use an 8mm socket to fit the splash shield and its twenty-three bolts.
BMW N20 & N26 Oil Filter Housing Gasket Torque Specs:
- BMW Oil Filter Housing Bolts = 22Nm or 16.2 ft-lbs, of torque
- BMW Oil Cooler Bolts = 18Nm or 13.3 ft-lbs, of torque
- BMW Oil Filter Cap = 25Nm or 18.5 ft-lbs, of torque
- BMW DME Bolts = 12Nm or 9 ft-lbs, of torque