Moisture in rear engine oil

[Peyton]

Aircraft: 1967 Skymaster

Rear Engine: IO-360-C-1B SN:060635-R

Problem: High moisture levels in oil reported on last two oil analysis (Blackstone Labs).

Guys - This engine is five years old and has had oil analysis performed with each oil change. I have never had this problem before the last two oil changes.

I have a GEM 1200 and Shadin Fuel Fow installed and nothing unusual is showing up in the operating parameters and all numbers remain where they have been for the last five years. The only noticed change is possibly a very slight increase in oil temps and corresponding reduction in oil pressure (all remain well within the green).

I am the sole pilot of this aircraft and hours flown (130 / yr), power settings, etc are unchanged from past procdures. This engine is being flown at the same settings as the front engine which is not showing this moisture problem. The only difference in equipment between the two engines is the installation of an air oil separator on this rear engine which was done 4 years ago.

Can you please help with suggestions as to what might suddenly be causing this oil contamination problem?? What do we look for?

Peyton (peytonmcco@aol.com)

[Bob Cook]

Peyton

This is not unusual...

1) keep temps up above 170.
2) do not start up unless you fly for 1 hr at 70% power.
3) cruise with higher power levels (above 65%).
4) Insulate the oil breather tube (long neck).
5) Fly often.
6) Fly often.
7) Fly often.
8) Fly often (more than one hour).
9) Fly often!
10) do not idle and keep mixtures lean - on the ground.
11) Change oil every 30 hrs or 90 days.

There is only one cause for water in oil and that is Condensation !


hope this helps.

bob

[Dale Campbell]

The answer is simple. I also installed oil/air seperator on both engines. I also had water in oil, mainly in winter & mainly in rear engine. The water that you had in engine before you installed air/oil seperator, blew out breather pipe with some of your oil.
Now you have to seperate oil from air and some of the water wants to stay in engine. Also if you mounted the air/oil seperator like you were instructed and as I did. It is mounted up high in direct path of air coming in through air scoop. That cools oil in metal air/oil seperator causing water to seperate into droplets and going into oil pan. The secret is to wrap the pipes and the air/oil seperator with water pipe insulation. And also in winter block off some of the oil cooler, to allow tempature to stay a little higher around 190 degrees so the water stays in vapor form and can be blown out with the air. Now that was simple, was it not. It works, try it. Dale Campbell

[Peyton]

Thanks Bob and Dale!

[atsiii]

Peyton,

I too had water in the rear engine resulting from the install of an oil/vapor seperator. Dale is exactly correct... it is condensation from the seperator which in my case, was freezing in winter and also presurrizing the case. I ended up removing the seperator and the engine went back to breathing normally. Dale's suggestions (insulation) are probably better.