BMW E46 M54 Engine Excessive Oil Consumption

An Ard Ri

Hello,

I have an 04 BMW 320Ci with 79k miles.

It had always burned oil, from research this is common enough with the M54 engine. However, the oil consumption has got consistently worse, and now it burns 1 litre approximatley every 700 miles, which clearly is not good! Otherwise the car drives perfectly. It has a full service history. There are no signs of any oil leaks.

The car is due a serive in the next few weeks, and i'm going to point out the excessive oil consumption. Would anyone have any experience of this problem, and what could be the cause? The research i've done, largley on American sites, has thrown up numerous possible causes, but nothing concrete.

Thanks in advance.

rebel.ranter

There's a few reasons for excessive oil use in the M54

- CCV crankcase ventilation valve, also called PCV. This is an oil separator valve system that maintains the vacuum in the oil system in order for it to function correctly. The valve can fail & also the pipes can crack, this leads to the loss of the vacuum creating a condition that allows oil to be burned. About €150 for OEM parts (recommended) & the same for labour.

- Rocker cover gasket has failed, the rocker cover gasket fails on the M54, without fail. The rubber gasket gets brittle & hard over time, eventually allowing oil to weep out, particularly at the rear of the engine. Sometimes you might notice a burning oil smell when you start the car after it has been parked up for a while. The part is ~€70 OEM (recommended), but when you're doing this job don't forget the change all the rubbers for the bolts too, penny wise pound foolish not to.

- Oil leak from the base of the oil filter housing. This is another seal that is a weak point of the M54 engine. It requires a bit of ripping to get to it, you'll have to bleed the cooling system after as the thermostat housing has to come out to give access. This is another seal that allows oil to weep out, as with the seal above it is unlikely you'll see oil on the ground, it just weeps along the block & burns with the heat as you drive.

- Faulty seal on the oil cap or on the dipstick. Check both of these for a good seal.

- Worn valve stems or piston rings. Get a compression test to rule these out

Hope this helps.

cgarrad

I have a 02 318ci with a N42 engine, goes thru 1l every 1000 miles.

Well known sh1te engine!

Only way to look at it is always clean oil in the engine

An Ard Ri

Thank very much for the info.

rebel.ranter wrote: »

There's a few reasons for excessive oil use in the M54

- CCV crankcase ventilation valve, also called PCV. This is an oil separator valve system that maintains the vacuum in the oil system in order for it to function correctly. The valve can fail & also the pipes can crack, this leads to the loss of the vacuum creating a condition that allows oil to be burned. About €150 for OEM parts (recommended) & the same for labour.

- Rocker cover gasket has failed, the rocker cover gasket fails on the M54, without fail. The rubber gasket gets brittle & hard over time, eventually allowing oil to weep out, particularly at the rear of the engine. Sometimes you might notice a burning oil smell when you start the car after it has been parked up for a while. The part is ~€70 OEM (recommended), but when you're doing this job don't forget the change all the rubbers for the bolts too, penny wise pound foolish not to.

- Oil leak from the base of the oil filter housing. This is another seal that is a weak point of the M54 engine. It requires a bit of ripping to get to it, you'll have to bleed the cooling system after as the thermostat housing has to come out to give access. This is another seal that allows oil to weep out, as with the seal above it is unlikely you'll see oil on the ground, it just weeps along the block & burns with the heat as you drive.

- Faulty seal on the oil cap or on the dipstick. Check both of these for a good seal.

- Worn valve stems or piston rings. Get a compression test to rule these out

Hope this helps.