Slight Oil Misting Inside Windscreen

[R-Banger]

So I have a really weird issue. When I fly the plane there is a very slight bit of oil misting on the inside bottom 2-3 inches of the windscreen. I wipe it off and one flight later it’s slightly blurry again. So this is not the typical misting on the outside from bad prop seals etc. The engine bay is spotless too. Does the oil route inside for the oil pressure gauge? I have the original gauges so I am assuming it is a mechanical pressure gauge. 

[EricJ]

11 minutes ago, R-Banger said:

So I have a really weird issue. When I fly the plane there is a very slight bit of oil misting on the inside bottom 2-3 inches of the windscreen. I wipe it off and one flight later it’s slightly blurry again. So this is not the typical misting on the outside from bad prop seals etc. The engine bay is spotless too. Does the oil route inside for the oil pressure gauge? I have the original gauges so I am assuming it is a mechanical pressure gauge. 

If the misting is near the gauge cluster or where the wet line is routed, that's probably it.   It might be a loose fitting or early indication of a fracture in the line.   On older airplanes the fuel pressure (or fuel flow) and oil pressure gauges are wet, and the oil temp gauge may be wet as well.   

 

[Nukemzzz]

Seems like a reasonable theory to me. Maybe should look behind the panel for oil before your next flight. Good eye by the way. 

[takair]

Is it possibly coming from your defogger duct?  Any chance you have new scat tubes?  Is it just foggy or wet? Oil could also be getting inside your muffler heat muff and then getting through your heat system?

[Yetti]

Them there are your two options

 

[carusoam]

On the inside of the window...

It would be difficult to NOT leave a good trail behind...

If it is related to the defrost system... the oil will be appearing right where the defrost outlets are...

 

If it is an oil pressure line... it is unlikely to have vaporized oil... floating out unnoticeably...

Reach up behind the oilT and OilP gauges... if everything back there is slippery.... you know why...

Go behind the fuelP gauge as well... in the event that isn’t oil you see on the inside of the windscreen...

If vaporized oil is landing on the windscreen... drips of oil will be heading for the carpet...

Ise caution with the MP gauge... bumping it can result in breaking open the calibrated leak hole... visual inspection of the MP line may reveal blue staining...there is some fuel at one end of this line... and vacuum at the other... it is possible that fuel get emitted from an open line...of course your MP will read a preposterous number like 33”...

 

What usually happens during the annual... there is a fair amount of engine cleaner sprayed about liberally...

That solvent and what it cleaned... are resident in the heater system.... and start boiling away the first time the engine warms up....if your heat system is open... (on)... you might see white wispy clouds of vapor come out.  Enough to think you might be seeing smoke...

 

Give it a sniff... compare to the engine cleaner of choice...

Has anyone cleaned the engine recently, like during a PPI or annual?

Best regards,

-a-

[RLCarter]

3 hours ago, R-Banger said:

So I have a really weird issue. 

Yes you do! Is it all the way across the bottom? Will be interested in seeing this play out

[R-Banger]

10 minutes ago, carusoam said:

On the inside of the window...

It would be difficult to NOT leave a good trail behind...

If it is related to the defrost system... the oil will be appearing right where the defrost outlets are...

 

If it is an oil pressure line... it is unlikely to have vaporized oil... floating out unnoticeably...

Reach up behind the oilT and OilP gauges... if everything back there is slippery.... you know why...

Go behind the fuelP gauge as well... in the event that isn’t oil you see on the inside of the windscreen...

If vaporized oil is landing on the windscreen... drips of oil will be heading for the carpet...

Ise caution with the MP gauge... bumping it can result in breaking open the calibrated leak hole... visual inspection of the MP line may reveal blue staining...there is some fuel at one end of this line... and vacuum at the other... it is possible that fuel get emitted from an open line...of course your MP will read a preposterous number like 33”...

 

What usually happens during the annual... there is a fair amount of engine cleaner sprayed about liberally...

That solvent and what it cleaned... are resident in the heater system.... and start boiling away the first time the engine warms up....if your heat system is open... (on)... you might see white wispy clouds of vapor come out.  Enough to think you might be seeing smoke...

 

Give it a sniff... compare to the engine cleaner of choice...

Has anyone cleaned the engine recently, like during a PPI or annual?

Best regards,

-a-

I am going to start with this as the plane was annualed in April and pre-buy beginning of May. Could be very likely. Flown 30 hours or so since then. Waiting for my edm 900 To arrive and will have it all opened up for that so will report back on my findings.