[N43B20A]

Hello everyone!

I have a low mileage E90 which started to need a lot of oil lately. About 1L/1500 kms.
I am not sure if there's a leak somewhere or it is burning oil. Is there anybody who owns a car with this engine and had the same problem? What are the things I should check?

Any advice is appreciated.

Thank you!

[Fritzer]

I sort of wish we got these little 4-bangers in the states. The 320si has a really sweet engine!

As to your issue, I'm not familiar with these particular engines. However, I will go off of standard oil leak issues in the N51/52. Get a good flashlight and inspect your engine from the top, front to back and left to right. If you're losing a substantial amount of oil from a leak you should notice right away. Check the valve cover gasket, the head gasket, oil filter gasket, and any other gaskets on the front of the engine. Finally, check any other seals/gaskets on the engine that could be leaking, look for bolts with sheared heads that could be seeping oil. Additionally, inspect the oil pan gasket from below the car.

If you see any oil on the engine, follow the stream from the bottom to the top and you will find your source.

What was your oil change interval, how many miles on the vehicle? Have you observed any oil on the ground after leaving the car parked? Do you have any other power train issues or symptoms, smells or excess smoke?

[N43B20A]

Hello, Fritzer!
Thank you for your reply.

Only 78.000 km with the car. Bought it new and changed the oil every 10k at most. Apart from the oil consumption, the car runs fine.

Last week I got an 29F4 error ( CO catalytic converter efficienct below threshold value - the first one after the exhaust, not the NOX one). I am not sure if it's related or not. If it's indeed burning oil it may hurt the catalytic converter hence its inneficiency. I am not sure if this engine has a PCV valve (positive crankcase ventilation). Maybe it's broken and the oil goes into the exhaust and that is another reason for the converter to show errors.



Will do an in depth inspection during the next weekend. I am not sure if this engine has a PCV valve (positive crankcase ventilation).
Have a great day!

[N43B20A]

Hello, everyone!

I've gone to the mechanic for inspection and he couldn't find any leaks. He is assuming that the valve stems seals are faulty.

Any idea if it's an usual problem at this N43 engine? Are they hard to change?

Thank you greatly for replies.

[N52bigblock]

Yes valve stem seals are a normal issue for the 4 cyls and a lot of other BMW engines. If BMW could actually learn to make decent seals and gaskets it would be fantastic. Don't think they ever will though. Maybe Toyota taught them a few things with the new Z4/Supra. It takes about 8-10 hours to replace them. Big job. Stretched timing chains are another big issue for the 4cyl as well.

[N43B20A]

Thank you for your reply! Is there anything wrong If the valve stems seals are indeed faulty and not replaced? I can live up with this oil consumption. Replacing them seems a pretty big job...

[Bimmer_Engineer]

Originally Posted by nclsamy

Thank you for your reply! Is there anything wrong If the valve stems seals are indeed faulty and not replaced? I can live up with this oil consumption. Replacing them seems a pretty big job...

If you’re burning that amount of oil through the motor then I would expect it to plug the cats eventually and start causing CEL codes. I’ve got something similar but not quite as severe on my n54. As an aside if you were leaking that much oil rather than burning it I would expect it would be pretty obvious.

[N43B20A]

Thank you for your reply.

Any idea how/if the valve stem seals can be tested? Or what should be a symptom that they're failing?

[N52bigblock]

The easiest way to tell is to firstly get the engine hot, then leave the engine idling for 10 minutes, then give the engine a rev, up to about 5000rpm. Watch the exhaust while you are revving it. You will see a cloud of blue smoke if the stem seals are bad. It is very common, even at low mileage.
And bimmer_engineer is correct in saying your catalytic converters will eventually fail if the seals are not changed. They are very expensive to replace too. I would just get the seals replaced to avoid future issues.

[N43B20A]

Thanks a lot for your replies!

Yesterday, after a 15 minute drive in the city, with the engine running only under 2000 rpms, I took it for a run on the highway. It started to exhaust blue smoke above 4000 rpms and only for a few minutes.

It seems that the Valve stem seals are indeed faulty, right?

My problem is that I was not able to find any other case of Valve Stemseals failing on this engine on the internet.

On the other hand, it seems that the PCV (Positive crankcase ventilation) valve breaks more often. Should the symptoms be the same as failing Valvestems seals?

Thanks everyone!
Have a wonderful weekend!

[N52bigblock]

Try the idle for 10 mins test i posted previously then let us know what it does.

[N43B20A]

Sorry for the late Reply. Unfortunately I was extremely busy and did not have any free time to deal with the car.

Yesterday I let it idle for 15 minutes and then Reved it up to 5000rps. A lot of blue smoke came from the exhaust for about a minute or two. I should have filmed it, but I was alone.

[ptpending]

if you had pcv system broken then you'd had oil leaks around motor, because bmw pcv system designed in a such way that if it do not separate oil and exhaust in right way - it is pushed via weak seals which bmw specifically made weak
the problem with valve stem seals is quite common for bmw petrol engines but it is more common if you have more urban mileage than highway mileage due the reason that in city bmw engine operate in high temperature mode to meet strict exhaust requirements
and valve stem seals which made from rubber are literally "baked" to plastic and became not so fit as new
also your N43 engine require high temperature to operate in stratified mode which is designed using high pressure injectors and pump to provide more fuel efficienty then more simple N46 engine

as for 320si with N45 engine , this car is made by bmw to pass omologation of the sport track car and you can dig mobile.de site to see that about one third of the 320si cars sold with Motorschaden(engine failure) problem. So this engine is MORE unreliable than N43 and N46.

[N43B20A]

ptpendig, thank you greatly for your reply.

Indeed, about 80% of the car's mileage is urban, so it makes sense for the valve stem seals to fail.

On the other hand, after hard driving it on the motorway there is some smell of burnt oil in the cabin. My friend, the mechanic, said that it's relate to the vacuum pump gasket that is leaking, so next week I am in for the replacement of valve stem seals, valve cover gasket and vacuum pump gasket.

About the pcv system, there is no oil that I can see leaking from other gaskets. But if it was oil in the exhaust from a faulty PCV wouldn't the symptoms be the same as it were the valve stems faulty?

Have a great evening everyone!

[N43B20A]

Good morning!

Last week I have replaced the Valve Stem Seals. The mechanic said that at least 4 of them were pretty loose. The Vacuum and Valve Cover seals where also leaking, so they were replaced as well.

Now, after 30km there is no more smell of burning oil in the cabin (I can assume it was a consequence of the Vacuum and Cover seals failing).

The big problem is that the car still smokes when Reved after it idles for about 10 minutes.
I have no idea what could be wrong? I don't know yet how much oil it burns, since I've only done a few kilometres.

Any advice what could I do next? Can the PCV valve be the culprit?
Unfortunately it is built in in the valve cover so it must be replace as a whole.

Thank you all in advance for your replies! Have a great day!

[Camery]

It could also be the piston rings / oil scraper rings.
I had mine replaced on my N46, alongside the valve stem seals, and the oil consumption is almost none. (you will never get it 100%).

I wanted to go for just the valve stem seals first, but the mechanic who has seen dosens of these engines said is usually is a combination of both (seals and rings)

Then again I am not sure if the n43 has the same issues, but it was produced along side the n46 at the same time, so it could definitely be.

Please be aware though that replacing the piston rings can be costly.

[marvinstockman]

Contact BMW and ask what they can do for you. Don't take no for an answer, but always be nice.

What type of oil are you using? If 5W30, then switch to 5W40, or even 5W50 (if you can find it).

[N43B20A]

Originally Posted by Camery

It could also be the piston rings / oil scraper rings.
I had mine replaced on my N46, alongside the valve stem seals, and the oil consumption is almost none. (you will never get it 100%).

I wanted to go for just the valve stem seals first, but the mechanic who has seen dosens of these engines said is usually is a combination of both (seals and rings)

Then again I am not sure if the n43 has the same issues, but it was produced along side the n46 at the same time, so it could definitely be.

Please be aware though that replacing the piston rings can be costly.

Thank you for your reply. Yes, I am aware that it could be the rings that are faulty. Before I'll change the rings will give it a try with a new rocker cover with the CCV valve.

Originally Posted by marvinstockman

Contact BMW and ask what they can do for you. Don't take no for an answer, but always be nice.

What type of oil are you using? If 5W30, then switch to 5W40, or even 5W50 (if you can find it).

Unfortunately there is no chance I can get a Good will from BMW. The car is 11 old.

I am using 5w30 BMW oil (made by Shell as far as I know). I will chose 5w40. What brand is better?

[N43B20A]

Hello, friends!
Next week will do a compression test and will change the oil to Liqui Moly 4100 5W40. Unfortunately it seems that the oil piston rings are indeed faulty.

I am not sure the repair makes sense from a financial perspective. Sadly, I may need to sell the car for scraps.

Have a wonderful weekend!