Possible Valve Stem Seal Leak?

[86BOY]

I'm after another opinion on what may be a failed Valve Stem Seal. The last couple of days I have had White/Bluish exhaust smoke but only when decelerating and coasting with the clutch in (idling), basically when the engine is at its highest amount of vacuum. I get no smoke what so ever when at a cruising speed and while on Boost. My first thought was head gasket, but I'm not running hot and there is no oil in coolant or vice versa. This smoke smells oily, same smell as driving behind someone with worn piston rings.

PCV valve is fine and I have been running a catch can. I took the breather from that and put it directly on the valve cover to rule out any blockage which would cause major crankcase pressure and direct the oil back up into my turbo oil return hose, thus leak past the seals and into the intake and exhaust sides of the turbo. I have had no issue with my oil drain and has been working fine for the past 9 months, that being said I may run some clear hose to double check that. Boost pipes are also clean with no sign of oily residue what so ever.

A misfire on startup (can be hot or cold) will sound like it's running on 2 cyl for about 5 seconds then runs fine (fouled plug?) There is no loss of coolant and I haven't been driving it much to see the oil level drop. If I'm heavy on the brakes while coasting, it literally looks like I'm on fire from the back of the boy which from what I have read is a symptom of oil collection being sucked through the valve stem while idling.

The only thing I have done recently is back the boost down from 8psi to 5psi because my clutch is junk and slipping. Help and other peoples thoughts/opinions are welcome!

[Zuffen]

I would agree with your diagnosis.

Whilst replacing the seals is easy, you could also have worn valve guides as they should contain oil passage to an extent..

At least replacing valve step seals is cheap and fairly easy (no head off) so I would give it a go first.

[86BOY]

Thanks Zuffen, the guides were another option to look into as well. I'm aware of being able to keep the head on while doing the seals after putting pressure in the cylinder to keep the valve seated shut. I'll pull the cover off and see if there's side to side play with any of the valves, It'll at least be a lead to this cause! Thanks again

[Zuffen]

Another option to keep the valves in place is to fill the cylinder with string/small rope and wind it up to TDC, or as close as it will go.  This will stop the valve dropping.

Let us know how you get on.

[86BOY]

Excellent, I'll keep that in mind. That may be the easier way to go about it and I'll definitely keep an update on this.

[Brayden]

Quickest way to diagnose the problem is a leakdown test.
Or if you're confident it is a valve seal issue then check the plugs - one will likely be black and gummed up with oil.

Crank case pressure will never be enough to force oil out of the turbo seals. You'd blow the sump and rocker cover gaskets well before that happened!

[86BOY]

Cheers Brayden, I'll definitely look over the plugs first. Tomorrow I'll start it and shut it off straight after its misfiring, which I'm sure there is oil fouling one of the plugs until it clears enough to run smoothly on 3 cylinders again. Good to know if there is ever an issue with the crankcase, I'll look for a big oily mess at the rocker cover or sump haha.

[86BOY]

Well I have now misdiagnosed this problem because the No.3 cylinder spark plug had coolant on it when I checked all of them after the misfiring cold start. I even put a piece of paper in front of the spark plug hole and cranked with injectors unplugged, spitting out obvious remains of green coolant. I'm now certain the intake manifold has a bad bit of gasket (cork gasket) which I can also see coolant seeping at the very top. It's either this or the head gasket is still a possibility, even though there are signs of coolant sitting around my intake gasket so I'll start with that.

I went from the standard thin OEM gasket (which eventually leaked), to the cork gasket because its thicker but may not like boost all that much. I may end up sourcing a decent gasket material and re-facing the adapter plate as I have a feeling its not all that flat, causing a leak with a standard manifold gasket.

[Brayden]

I cut my inlet gasket from a roll of material that is slightly thicker than the factory gasket - when I say slightly I mean a fraction of a mm.
Hasn't leaked in a decade of hard boostin'.

[86BOY]

Haha I took my manifold off last night and removed the cork gasket from both sides of the adapter plate and they were absolute crap. The fuel that has passed through over many months have eaten away around the port hole areas. The cork gasket which is 3mm thick has been ok up until now, I didn't hold much hope for longevity of it anyway. I have ordered an A4 size 'Nitrile Butadiene' Rubber sheet which is fuel resistant and the same thickness as the cork gasket. I should have looked into this when making my own gaskets in the first place!

[86BOY]

I have had the Boy off the road far too long for my liking but recently dropped the motor back in. I installed a HD clutch and while the motor was out I tidied up a lot of hoses, wiring etc. The original thread topic was about valve stem seals which was completely mis-diagnosed and found the cause to actually be my crankcase not breathing after all.

I had oil backing up the turbo oil drain and leaking past the seals into the exhaust housing. I tested this with a clear hose on the oil drain and as soon as I saw the oil creeping back up the hose, I'd take off the little breather and the oil would go back down, flowing the way it should. So the little culprit was that little breather being almost completely clogged with oil to the point where you could barely blow air through it, so I could only imagine the motor suffering!

There is nothing worst than having an issue like this where you are wracking your brain to find the cause. Now that its sorted, I can sleep well at night now!