Air-oil separators

[kevin]

I received the email below. I am fairly sure I have seen this topic go by before, does anyone want to comment? -KM

Do you know of anyone who has installed an air-oil separator on their Skymaster engines. My plane ends up with oil on the rear engine cowling and tail. I was wondering if these separators have been installed in other Skymasters, and what their success has been. Thanks for any help you can provide. My Skymaster is a normally aspirated 1971 model with IO-360C engines.

Yours for Christ,
Cliff

[Jerry De Santis]

Cliff, If the oil is getting on the rear engine cowling, I suggest you check for oil leaks from the front engine. Check the oil filter adapter. I have not seen oil from the front exhaust get to the rear engine cowling, but I have experienced front engine oil leaks that drafts up on to the back cowling.

Cheers and Merry Christmas
Jerry
N34EC

[Kevin McDole]

Cliff,

My 1977 P337 has oil/air separators as stock equipment - they look very much like units offered by M20.

I have no before & after experience with the 337, but I have tried both the Walker (now Wolfe) and M20 oil air separators on my T210N. The bottom line is they both work as advertised. They greatly reduced the oil on the belly of the 210.

The pros and cons of each are open to debate. The Walker unit requires a connection to your vacuum system, and it’s argued that this allows warm air into the gyros after the engine stops. Theoretically this promotes condensation inside the gyros. Finding room for this unit under a 337 cowl may be a challenge. My shop damaged the Walker unit at one point, and we had lots of trouble getting the seal between the two halves to stop leaking oil. Walker was out of business at the time, so I ended up switching to the M-20 unit. By the way, the M-20 is a one piece device – gasket-less.

The M-20 unit is smaller and requires no vacuum connection. However, it took me about a year to get it working correctly. Bill Sandman from M-20 was always very willing to help. My shop had not installed the unit correctly, and despite phone calls to M-20, they could not see their mistake. As soon as I provided a digital photo to M-20, they were immediately able to explain what we did wrong – and once corrected, it worked perfectly. In a nutshell, oil flows downhill and the separator must be higher than the tube that returns the oil to the engine – and the return tube must not be below the oil line in the valve cover.

I recommend both units – but I have a slight preference for the M-20 due to its size and lack of connection to the vacuum system.

There’s an article at AvWeb on the M-20:
http://www.avweb.com/articles/separator/

M-20’s website:
http://www.m-20turbos.com/breather.htm

Walker’s website:
http://www.airwolf.com/Products-WalkerAIRSEPS.htm

[mhudsonbsme]

Does anyone have pictures of m20 engine oil separator installations on the front and rear engines?

Thanks