540i/6 puff of smoke start up

[dog man]

Hi All

After fitting a new pcv plate, inlet manifold gaskets and throttle body gasket I seem now to have one or two more problems that I didnt have before, namely, smoking on startup....I am not ruling worn valve guides out but I just dont buy it...the car reads 140k but had BMW short engine 3 years into its life ('94 car, engine in '97) so I'm guessing 100-120k for the short engine.

It'll even puff after just an hour or so...now to me it would have to have seriously worn guides to do this which I just dont think it has...the car isnt a show winner but its bloody tidy and money has obviously been spent by PO's

It does have an oil leak somewhere as after running on the motorway you can smell a faint oil smell so this doesnt help oil consumption but never the less it seems to use a hell of a lot of oil but doesnt burn any under load - I have just got back from a round trip to France and managed 500miles from a tank and some quite impressive speeds with 4 adults on board!

And the other thing it didnt do until I changed the oil is noisy tappets first thing in the morning. When you remove the oil cap whilst running you get lots of crankcase fumes coming out and little change in idle and with the dipstick removed there is no cange at all - certainly there is no sucktion over the dipstick tube.....whats going on!!???

[Ross]

Sounds like the crankcase isn't being properly ventilated or overwhelmed with blowby. Also sounds like it doen't like your choice of oil if it suddenly became noisy.
A leakdown test might be in order. A lot of your symptoms point to a tired engine.

[dog man]

I used semi synthetic 10w40 and had also thought like you did about different oil....what would I try next oil wise?

I understand the theory of being overwhelmed by blow by but it just seems that the engine would be puffing under load if it were that bad, i.e I am thinking (hoping) more along the crankcase ventilation route...oils/vapour separator?

[Ross]

10/40 should be okay. I use conventional oil unless manufacturer specifically states to use synth.
If your old oil was really old and loaded with carbon it may have masked these symptoms. An old Datsun I once bought had extremely filthy oil and after being changed it smoked like a motherf. Not until several loads of oil thickener were added and some miles put on it did the smoking diminish.
From what you are describing I agree that the ventilating is more likely at fault.

[dog man]

I agree that the ventilating is more likely at fault.

Yeah, it pulls well and I got 500 miles from a tank so I'm not too worried but it just seems like maybe something fairly simple is at fault. How about the theory that the oil pump may be loose thereby screwing the ventilation up?

[Ross]

Oil pump loose might account for the ticking at startup. Can't conceive how it would effect crankcase ventilation.

[dog man]

Can't conceive how it would effect crankcase ventilation.


I know me either....doh!......