That's an interesting test, I've not heard of that being done before! What are they generating the smoke with?tearing hair out wrote: ↑07 Jul 2023, 16:00 Bad news for me, unfortunately, I think. The garage has discovered that smoke pumped into the inlet, with the engine off, comes out of the dip stick. I guess the piston rings don't seal especially well at low pressure, but I'd not expect a particularly quick leak that way.
I'm surprised any meaningful amount of smoke pushed into the inlet could appear at dipstick without massive internal engine problem (like a piston with a hole in it!!)
Actually! Brain has clunked into action now:
PCV positive crankcase ventilation = that is a route between inlet manifold pipework (normally pre turbo inlet, low pressure side of inlet) and the crankcase, via the (large unrestricted oil drain routes through the head)
I'd be pretty confident you/they were detecting a failed PCV valve (normally a diaphragm on the connection on cylinder head) providing a route to the dipstick.
Blank that off (normally 19 to 25mm rubber hose between inlet and cylinder head cover) and see if smoke disappears would be my suggestion.
Especially ahead of:
As above, leaky rings would still be a very small route for this smoke to travel throughIt sounds like a reconditioned engine - which is almost certainly too expensive. Anyone able to offer me any hope that we're missing something?
EDIT: There is a doubt in my mind - if you pump smoke into the inlet, it's got to come out somewhere... And if the only path is past the one (probably) open inlet valve into an otherwise-sealed cylinder - that's pretty much got to be past the piston rings. Presumably the piston rings naturally seal better when the cylinder is in motion.