Puffs Of Smokey Air When Oil Cap Is Removed!?

[mhyphenl 10 1 Cars]

While my engine is running, if I take off the oil cap, I get quite a bit of air movement with water vapour / smoke in it. If I put my hand over I cant really feel any pressure. I just don't know how much air movement / exhaust fumes etc to expect to escape, I'm about to rebuild after another issue but not sure if this is a sign that the piston rings need attention??

[dcc 855]

The oil filler cap is the last part of the breathers where oil vapour will travel before it get recirculated back in to engine. These engines are quite old and dare I say most of them fairly worn when compared to new. A bit of oil vapour is to be expected and doesnt sound anything other than normal

[mhyphenl 10 1 Cars]

That's true enough, it's whether spending £100 on rings is worth while, there seems to be barely any wear on the liners, no lip at all, engine done 78000 genuine miles!

[pug_ham 244 3 Cars]

TBH, unless the engine was a smokey dog that burned oil for fun then I wouldn't be too concerned.

 

The air you can feel coming up the breather is displaced by the crank rotating & pistons travelling in the liners so you are bound to have some slight pressure, it's displaced the equivalent of 1905cc of air every rotation!

 

g