BMW E46 316i and 318i M43 engine oil filter housing leak
March 5th, 2012
Today we have Georgina’s 316i in to repair the large oil leak from the oil filter housing. This problem is very common on the M43 engine and we’ve seen cars with as little as 20k miles showing early signs of oil leaking from the filter housing where it joins into the engine block.
as you can see in the pictures below there is lots of fresh engine oil all over the underside of the engine.
So first up we need to remove the air box lid and air flow meter. This is straight forward for a DIY mechanic.
Then its time to remove the alternator drive belt using a 15mm spanner, just pull the belt off the alternator, no need to completely remove it from the car.
Once those 2 items are done you must undo the PAS reservoir 2 x 10mm nuts as below already removed.
lift the PAS reservoir/tank of its bolts and let it hand down and rest.
Now you need to remove the 2 x 16mm alternator bolts.
Once you have loosened the alternator you must undo the red power cable to it, ensure the battery cable is disconnected first. then unplug the electrical connector on the alternator also. Completely remove the alternator from the car.
Now you have access to the bracket that needs removing. This is removed by undoing a series of 13mm hex bolts pictured below.
and finally these 6 bolts that will remove the bracket from the car.
With the bracket removed you will have access to the oil filter housing. Remove the oil filter cap and the micro filter at this point if you haven’t already done so.
Undo the 6 x 10mm securing bolts for the oil filter housing, and remove the housing from the car as below.
Housing on floor.
Now you need to scrap off the old gasket from the engine using a stanley blade or gasket scraper tool.
Heres the new parts – a gasket and the oil fitting with O-rings. These o-rings are the cause of the leaks, they perish and become unable to seal the oil. You’l find the old fitting was very loose and easy to remove.
Fit the new gasket, new oil fitting (snug fit and pops when its pushed in to place).
Refit all the removed parts in reverse order. Take time to clean the oil residue afterwards, and run the engine for a while to check for any leaks.
A nice dry filter housing.
Cleaned engine ready to go.
Job done, a fairly simple job for a DIY mechanic with some experience, takes just 1.5 hours total to do and no special tools are required. Check oil level after completion and top up as necessary.