Belly Oil...
 

My 1969 skymaster, s/n 1155, normal aspirated has new overhauled engines with new factory cylinders and only 50 hours flown. However there has been an oil strip from the oil breather of the front engine, in the port side of the cargopod, after any flight that last 45 min. or more. The overhaul shop has performed compression checks to the cylenders with well over 70/80 results, has checked for any pressue inside the block, either with static runups, and flying the airplane with the manometer attached to a hose from a modified oil cap with a hose, with normal pressure results. I have kept the oil level to 7 qts., with a slight better result. Do you know of any better approach to resolve this, like changing the position , lengh or any other way of the breather? Oil consumption before the overhaul was about 1 qt. every 4-5 hours with the same belly or cargopod oil, so I asumed it was because the engine age. The actual oil consumption is about 1 qt for 8 to 10 hours. Can the cargopod, ligthly open cowlflap position, cause any aerodynamic turbulence that could create a vacuun in the oil breather?
Thank you for any help.

Jose L. Ichaso

Less might be better...
 

Jose,

Try using the 6-Quarts POH minimum for flights of less than a couple of hours, or 6.5 Quarts if you're shy about doing so... and that should clear-up your problem.

Also, make sure the whistle-hole in the lower part of the breather tube is clear of debri. You could also check to make sure the oil cap is fitting tightly... if it isn't, that will cause suction effect and a mess. Also check that the oil dip-stick "O"-Ring is still on the end of the stick.

Hope this helps... We don't believe the cargo pod or cowl flap arrangement is the problem. When you put more than 6 or 7 quarts in these TCM engines, they're just gonna throw it out...

SkyKing

One other thing to check is how the stick compares to actual oil quantity. On the O2 I had, I would put in 8 quarts after an oil change, and it would only read 7. As it didn't have a filter, that was the real quantity in the sump. Going to 7 quarts helped reduce oil out the breather, with no change in oil temp.

Jose,

An additional avenue you may consider is adding an oil/air separator. Here are links for the two most common manufacturers:

http://www.m-20turbos.com/

http://www.airwolf.com/Products-WalkerAIRSEPS.htm

I'm not sure of the availability of STC's for these products on your aircraft. Check with the manufacturer.

Jose,

I concur with Mitch and Skyking, run your engines at six quarts rather than seven, and check the calibration of your dipstick. This has worked well for me.

I would be careful considering the separators. I have heard several reports of problems with these, seeming to revolve around them freezing up in flight when not insulated properly. Others have said they just don't work that well. I have never had one on an airplane I own, so have no personal experience with them.

Kevin

On my 336 Iam Having the same problem the only diference bein the oil falls on the nose wheel pant. I have been adding 1 quart oil for every 2 hours flight but I allways fill it to the 10 quart line.

I will keep it to 8 quart or less and see what it does


Francisco

Thank you all for your sugestions, I will try lowering the oil to 6 qts. and the alibration and o ring at the oil dipstick.

Thank you again,

Jose L. Ichaso