smoke from breather hose

I assume smoke coming from the breather hose on the oil fill tank is a bad sign. Any ideas what I might be in for? It's fairly constant and very noticable when I have been on the freeway.

Thanks
Greg
66 912

[Jones Low]

In the olden days, the crankcase ventilation went straight into the atmosphere. I remember seeing hoses coming out and hanging from the valve covers with a little oily smoke coming out of them. Air quality control decided this was bad and so auto makers started to vent this oily smoke back into the engine via the air filter housing hoping it would get burned up by the combustion. I know on my 69-912 this vent hose goes into my right air filter housing (stock) and it gets that side all oily and greasey. I hear others just vent it to the atmosphere with a long hose hanging outside of the engine compartment (below engine?). Venting it into the engine compartment makes the engine compartment oily and greasey. I wouldn't plug it up since this would create undesirable back pressure in the crankcase. Check with others that have the same model year to see how crankcase ventilation was done.

Jones Low
69-912

[Green 912]

Some "smoke" when hot is normal. As the rings start to let more gasses blow by you will see more. Don't worry unless you get an oily "wind" when you rev it up.

[Ads912]

Hi,
My sheetmetal has a hole in it to allow the hose to go straight out the bottom. I've never noticed smoke coming from it. Like GREEN 912 says, too much smoke could mean worn rings and 'blow by'.

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Adam White
68 912 Coupe