Blue Smoke from the exhaust

[John77]

Hi every so often when I start my car in the morning there is a lot of blue smoke from the exhaust. It did it today and did it a few months ago. There is no timespan between when it does it. What causes this?
2011 Eclass estate.

 

[EmilysDad]

worn valve stem seals. Over night, oil seeps passed the valve stem seal into the bore, engine starts, oil is burnt off causing blue smoke. Seals are a few quid but .... generally requires the head removing to replace them. So if you're paying someone involves a fair bit of labour plus obviously gaskets.

 

[John77]

Thank you, but why is this every so often. Maybe tomorrow or 2 months time?

 

[DSK]

Blue smoke is certainly oil. If it’s infrequent then I’d say you probably have some perishing component allowing it to get into the combustion area. I’d always start with things like crankcase ventilation which I rarely hear about people doing but, really is a periodic service item in my book. Then check for any other lines which may be leaking oil. If it’s more frequent then I’d say same as the above post stem seals. If more catastrophic then pistons.


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[ajlsl600]

As a obove. Breather system valve seals turbo. If fitted, rings
Are you topping oil?

 

[John77]

Blue smoke is certainly oil. If it’s infrequent then I’d say you probably have some perishing component allowing it to get into the combustion area. I’d always start with things like crankcase ventilation which I rarely hear about people doing but, really is a periodic service item in my book. Then check for any other lines which may be leaking oil. If it’s more frequent then I’d say same as the above post stem seals. If more catastrophic then pistons.


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Thank you. No no excessive oil use.

 

[oigle]

If you let motor idle when hot for 4 or 5 minutes and then give it a rev, does it blow smoke? If so, usually valve seals. If you go down a long hill with foot off throttle and then blow blue when you accelerate again, it is usually rings.
Perhaps your intermittent smoke might be related to how hot motor was when previously stopped...