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Oil fouled spark plug/heavy oil consumption

19K views 25 replies 14 participants last post by  Arod0690 
#1 ·
Hi Guys,

Got an issue with my 2001 320ci. I've had it from new and it always seems to have needed a top up of oil every few thousand miles. However, the car has now done 85K and drinks more oil that it used to. I'm running Castrol Edge
0w40 and have noticed very occasional blue smoke when decelerating but not all the time.

I've noticed the old spark plugs (Denso Iridiums) where very tired and one in particular was very bad (Crusted and eroded) Now replaced them wiith OEM NGKs and as the pic below shows one is soaked in oil. Is this a valve stem seal problem?? Any help guys?

cheers,

Matt
 

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#4 ·
I agree that the thinner 0w30 should only make the oil consumption worse, but I'd be hesitant to use anything thicker than 0w40. There are probably some additives that you could use to help freshen up the offending seal, but that should be unnecessary on such a relatively young engine.

I actually had to go and look up what "knackered" means :)....but yeah, it looks like it's just one seal on whatever cylinder that oily plug was removed from. The seal shouldn't have failed this early through normal wear and tear, so I suspect that it might've been bad from the factory..
 
#5 ·
Sorry for the "knackered" Steve :)

Valve seal job looks a bit tough to me. I would like to have a go at it though.

I think you need some VANOS & cam tools, and an airline to reset the VANOS unit whilst you take it off. Would like to know what tool the mechs use to hold the valves in place to stop them dropping into the cylinder whilst doing the seals??

Any advice appreciated.

Cheers,

Matt
 
#7 ·
Um, the valve cover gasket is not going to do anything for you.

It is your valve seals. This can be done by a shop without removing the head, but it is almost as easy to just remove the head. Might as well get a port and polish done, and a three angle valve job too...

Maybe cams??
 
#8 ·
I assume the Euro models have a PCV (crankcase vent valve, oil separator, whatever) like the US models.

It could be a failed oil separator is not separating oil from the crankcase gases, instead just dumping the oil-laden gases into the intake. Seems more common than valve problems, and certainly easier to fix.
 
#13 ·
Update

Just had my Valve stem seals replaced and to my dispair the car is still using oil and the same spark plug (no.5) is wet and black with oil! :-(

Not sure what else this could be. Both compression and leakdown test proved to be ok.

Any ideas before I set fire to it??

Thanks,

Matt
 
#20 ·
A compression, and much less a leakdown test will show much in the valve stem/guides area. Valves are closed and rely on the valve seats to produce a seal, thus preventing any detection of measurable leakage in those areas. This is because the valve stems/guides/seals are "upstream" of the valve seats.

If you are absolutely sure that the shop did in fact do a valve guide seal replacement, then I would look to the area of the valve stem itself and the guide. Could be that one has opened up a bit more than servicable tolerance or that some foreign matter has gotten in there and scored the surfaces. Obviously the head would have to come off to check for certain :(. The smoking on deceleration is a classic sign that your leak is somewhere in that area. Good luck.
 
#15 ·
The car came with 5w30 Esso Ultron when I bought it from new. I changed to 0w30 then 0w40 recently as it is supposed to be BMW Longlife approved. It was worse using 0w30 than 0w40, but why would one cylinder be very bad?

I have noticed that all the plugs have oil on the threads, could the oil be too thin?
 
#21 ·
LL-01 just means it can go the 24,000km distance between oil changes. Should still try and use the same viscosity oil recommended. Especially as it ages you may even want to use a thicker oil. But it does sound like maybe more issues than just your oil. But you should try an oil change first using the right grade and let us know if that helps.
 
#24 ·
I live in the UK. It cost me £400. The head was not lifted to do the job. Just a matter of putting compressed air in the spark plug hole whilst changing the seal.

With regards the Valve cover - not an issue. If it was I would have oil in the spark plug wells. :)
 
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