Oil on front cowl
 

I part own a Piper Archer2. Recently we have noticed every time we go flying we have an oil smear on the Starboard side of the engine cowl (bottom half of cowling behind the prop but about spinner height) . At first we thought it must be an outside culprit like another aircraft blowing it back but no it is from our engine somewhere. I am at loss to see how this gets forward of the engine,but must be prop wash doing it. We can't see a leak anywhere and are not loosing any great amount of oil. Can anyone shed any light on where this maybe coming from? I am betting someone else has had the same problem at some point. Any help would be appreciated.

You need to have an engineer look at. Clean all areas of the engine and apply some 'white' dust carry out a ground run and see where the oil is weeping from.

There is a rubber seal on the front of the crankshaft where it comes out of the crankcase, it's easily changed by an Engineer and is stretched and goes over the crankshaft flange with the prop off, have a feel around the crank / crankcase join behind the starter ring, it may be that.
See

http://www.lycoming.com/Portals/0/te...il%20Seals.pdf

Picture of seal

http://www.vansairforce.com/communit...d.php?t=104566

Another place may be the end plug in the crank, ( if it's a hollow crank ) this is a domed cap that goes in the end of the hollow crank and is punched in the centre to spread it and seal the end, easy change for an Engineer as above and requires prop off. (People often add a smear around it of RTV after installation in case it does weep )
See the expansion plug info at the end of this.

http://www.lycoming.com/Portals/0/te...0Corrosion.pdf

Picture of plug in place

http://www.chrisjgood.com/photo-log/...crank-plug.gif

From

http://www.chrisjgood.com/photo-log/engine.html

Other thoughts as above is check with your engineer to make sure he hasn't lubricated the likes of the starter as a little can go along way.

Hope they help you locate the leak, but as said get your Eng to have a look see to make sure it's nothing else.

EDIT

I would add after reading the link above re the end plug on one of the sites about using a ballpein hammer then hitting that with another hammer to dislodge the plug cap.
DO NOT AND NEVER hit a hammer with a hammer, they are both case hardened and can literally shatter and explode in your face if you do this.
..

Thanks very much Nutloose.Your info is much appreciated. I reckon you are on the money there and gives me a good idea where to look before I get a mechanic to fix.:ok: