M50 - Strange oil smell in car

[Rory525]

Hi folks,

Over the last few days noticed a strange problem.

After Ive left the car for a couple of hours, then gone back to drive it, after 5 mins of driving a sickly oil smell can be smelt in the cabin. It smells like oil fumes of some sort.

After maybe 3 or 4 mins this smell seems to go away and not occur again.

Anybody any idea what this could be? My only thought is maybe a blocked breather pipe somewhere ... only thing I can think of that releases nasty oil fumes.

Otherwise its running really nice, serviced it yesterday and its purring like a kitten again.

Any ideas appreciated.

[biondani]

Would be interested to know myself as mine does this as well.

Ian

[Rory525]

Would be interested to know myself as mine does this as well.

Ian

Maybe its only something 91 525 sports do lol

[Rory525]

Nobody else with M50 experienced this ??

No ideas what can cause it ? The smell was strong and sickly last night had to put windows down.

[632 Regal]

sorry Rory but I dont have an M-50, id guess that some oil is leaking onto the exhaust and burnung up when it gets hot. Chech it for leaks after driving it anf go from there?

[Rory525]

sorry Rory but I dont have an M-50, id guess that some oil is leaking onto the exhaust and burnung up when it gets hot. Chech it for leaks after driving it anf go from there?

Ill have a look for that Regal but I think thats ok. Its strange how it comes after 5 mins then goes away.

Does anybody know if there are breather pipes on the M50 which need cleaned out now and again ?

[Mas (UK)]

That it happens after a little drive is because the engine warms up and the leaking oil is heating up and burning off slowly or the hot oil fumes leaking out from somewhere.

First off and easiest way to diagnose the location of the problem is to follow your nose with your engine warmed up. I'd check around your valve cover, maybe the gasket is not sealing properly and leaking oil, probably onto your hot exhaust manifold. Sometimes it could be the gasket around your spark plugs, leaking oil into the spark plug chambers and getting heated from the hot plugs.

Secondly, check the crankcase ventilation 'plug' at the top of the valve cover is tight and not leaking oil. Check the rubber hoses coming off the valve cover if any have come loose or are old and damaged showing any signs of cracking. On the later M50 engines one of the smaller venting hoses goes under the intake manifold and plugs into a tiny nipple on the throttle body (I'm not sure if this is the same for your engine, hopefully the pro's here will be able to let us know). It could have come loose and basically venting the oil fumes into the engine bay and this gets sucked into the cabin. The other hose is bigger and also prone to degradation, so check it carefully.

Good luck.

Mas

[Rory525]

Thanks Mas I will check these things out.

Hoping its not some nasty oil leak thats hard to fix. Doesnt seem to use much oil really so cant be that bad.

[smcgowan]

Crankcase vent

http://www.realoem.com/bmw/showparts.do?model=HD63&mospid=47404&btnr=11_1284&hg=11&fg=15

Part 5 on the picture. Over time the hose dries up and cracks. The other end of the hose goes to the under the throttle body. Pain in the ass to see. I just felt may way.

The wife was complaining of gas and oil smells. After finding and replacing smells gone and oil consumpion= zero now.

[tnt525i]

same thing was happening with my M50, turned out to be the valve cover gasket, the gasket got old and started to leak just about a drop or two of oil on the exhaust side of the engine near the rear exhaust manifold, so oil would drip from the gasket and fall on the hot exhaust manifold, it would burn very quickly and smell inside the car, i pulled off the valve cover, used some silicone sealant and now no more oil leaks or oil fumes. hope that helps

[Paul in NZ]

sickly oil smell? Not antifreeze is it?

[Rory525]

sickly oil smell? Not antifreeze is it?

Nah its not antifreeze I know that smell... deffo oil smell.

Thanks for ideas guys.. will check for leaks onto exhaust and also that crankcase vent pipe.

[Bimmer93]

Well today I replaced my valve cover gasket on my M50 and it only has 100k on it. I had the same smell but it didn't hang around as long as yours anyway when I removed it (valve cover) the gasket completely broke apart and I had oil in my spark plug chambers. This job is very easy to do just look for a gasket set and make sure you replace the bolt gaskets around 15 of them. Cost about $45 and about 2 hrs of you time.

PS. One way to see your problem is run your car to full temp. then when you get home open you hood you might smoke or smell it mine was smoking from the back.

[Rory525]

The oil smell seems to have cleared up of its own accord strangely enough lol

I suspect my gasket will be breaking up a bit there too, as when I changed the plugs the other week a couple had some oil on the tops of them. Might get round to changing it when the warmer weather comes around.

Rory

[Rory525]

Ok I spoke too soon lol

Smelt it again tonight. Bizarrely its only ever when Im coming back from a certain pub I meet friends at ( sober of course ) . The car will be sitting for a few hours, then driven back along 40mph roads at 2000rpm. After a couple of miles I stop at lights and smell it then.

If I drive for another few miles it goes away. Strange ... never get it any other time.

[smcgowan]

Did you check that crankcase vent and hoses connected to it?

[Rory525]

Did you check that crankcase vent and hoses connected to it?

I havent yet as its been pretty cold here .. if its not too cold I'll check it out tomorrow. Hope its that as it would be a nice easy fix.

[ThoreauHD]

I had to replace my valve cover gasket as well, but the smell remained. It went away after I replaced the cabin filter. It's 13 bucks if you're interested. Needs to be replaced every 15K miles.. Mine looked like it was set on fire with a flamethrower. The smell is gone now. Nothing but clean air from the vents.


I had the same experience after driving for awhile. I suspect that when you warm up a nasty cabin filter it starts to release some of what it stopped filtering years ago. Just a guess on m part. All I know is that after fixing the problem and replacing the filter, it's not a problem anymore.

http://www.rockauto.com/catalog/catalog.php?carcode=1012048&parttype=6832&EPIsubcategoryID=322&EPIcategoryName=Cabin%20Air%20Filter&EPImodelID=17785&EPIengineID=2800&partGroup=24

[Rory525]

I had to replace my valve cover gasket as well, but the smell remained. It went away after I replaced the cabin filter. It's 13 bucks if you're interested. Needs to be replaced every 15K miles.. Mine looked like it was set on fire with a flamethrower. The smell is gone now. Nothing but clean air from the vents.



Is this the filter people say is hard to get to and change ? Where abouts is it ?

I have noticed a little oil seeping from the valve cover gasket so I will change this ... is it a hard job on the m50 ? do you have to take off the throttle body etc ?

[day]

hello rory525

there could be a slight leak leaking onto a manifold or downpipe some were.
but only when the cars stationary.
then burning off when you drive thats why it smells for five mins or so.

any thing else and i think you would smell it all the time.

good luck.

[day]

sorry.

i replyed to your post.

then noticed you had replys and read you found a leak.

happy days a least you know what it is.

im new to the site and still trying to find my way around.

bye.;)

[Rory525]

Thanks day , i *think* thats the problem anyway not totally sure.

Welcome to the site btw :)

[Rory525]

Ok I have another possible cause for this which Im 99% certain it is.

Since changing oil filter the other week, I noticed a little oil seeping out of the sides of the bolt that holds the cap on the filter container. Taking it off, I see the washer I got which sits under the bolt is mis-shapen ! GRR. So some oil has slowly leaked out and onto the hot top of the filter housing... burning off and the engine cooling fan blowing the smell into the cabin !

Just something to watch for when your changing ur filter - make sure the washers arent wonky ! Will need to pop down to bmw for one as I dont have any here, embarrasing asking for one stupid washer !

[fkong777]

I replaced the 2 valve vent hoses and smell went away.. They both dried up and cracked. Car also drive a lot better too.

Smell was really bad in my case.. I was getting headache and the smell got stuck in my nose for a while.