Did anybody fly an aircraft with.....

[recycled sixtie]

oil dilution? Now I am showing my age to be even aware of this strange phenom.
Radial engines in aircraft back in the 60's and before used to use oil dilution - that is gas injected into the engine oil in anticipation of starting in cold ambient temperatures the next day.

Pilots/aircraft engineers have any experience with this? How do you know how much gas to put into the oil? Was there a guage to show the amount of gas going in or would u just hold the toggle switch for so many minutes? I believe the gas was burned off by idling the engine for a time before takeoff. How long would it take to burn off the oil?
.

[FLYGEEZER]

The dilution amount ( time) was based on the outside temp anticipated. All "recip" oil as best as I can remember was SAE 50. The dilution process was the last thing to do before engine shutdown and was done at idle power. In the morning.. if the engines started..the gasoline in the oil would burn off or evaporate above 40 C. Engines were run at low power 1200-1500 RPM until the oil quantity indicator dropped to the shutdown quantity the night before and then topped off with fresh oil. The process took about a half an hour or so.The last recip I flew was the C124 & had 4 28 cylinder engines with a dry sump capacity of 100 gallons each. Oil dilution took a long time but had to be done if ya wanted to get the thing running in the AM. Ah yes!!! Those were the days. Wooden ships & iron men! Wern't any girly men on the crews back in the day.

[cashflyer]

You can't be that old. I'm only 45 and they were still teaching about it when I went through A&P school.

Here is an excerpt from a 1959 Cessna Owner's Handbook:

Oil Dilution System
(Optional Equipment)
To permit easier starting in extremely low temperatures, an optional oil dilution system is available. Used immediately before the engine is shut-down, this system injects fuel into the engine oil and reduces its viscosity. When the engine is again operated, the fuel evaporates and is discharged through the breather so the oil resumes its normal viscosity.

The oil dilution system consists of a solenoid valve on the engine firewall connected to the fuel strainer outlet, and to a tapped plug in the end of the low pressure oil screen on the engine. The valve is opened by pressing a push-button switch on the instrument panel.

Detailed operating procedures for the oil dilution system are contained in section III.


Also, check out this link:
Aircraft induction, fuel and oil systems., Page: 14 | UNT Digital Library

That page gives some details of operation, and the next page shows the injection valve assy.



edit: I have no direct exposure to the systems, so cannot answer your question about procedures.

[gamin]

Flew Navy Super Connies (EC-!21) into Argentia Newfoundland on occasion in the winter. We always used oil dilution at shutdown pretty much like flygeezer describes. Engines were Wright R-3350 turbo compound radials. Always started nicely the next day.

[bell]

” hey man......how many cylinders you got in that thing?”
”112.....”
”.........”

[allaircooled]

Originally Posted by cashflyer

You can't be that old. I'm only 45 and they were still teaching about it when I went through A&P school.

They are still teaching it as of 3 years ago when I went through an A&P school.

[FLYGEEZER]

Hey Gamin,, you lucky dog. I always wanted to fly the connie. Always looked like it was doin' 100 knots sitting still. I'm sure you remember that a pilot had to be under 25 years old to fly the connie..... anybody older, couldn't handle 3 pieces of tail at once.

[Seahawk]

Originally Posted by gamin

Flew Navy Super Connies (EC-!21) into Argentia Newfoundland on occasion in the winter. We always used oil dilution at shutdown pretty much like flygeezer describes. Engines were Wright R-3350 turbo compound radials. Always started nicely the next day.

Connies!

Did you know Howie Price?

[recycled sixtie]

Originally Posted by allaircooled

They are still teaching it as of 3 years ago when I went through an A&P school.

Then I would think that they would be covering their educational rear end because surely there are very few kinds of aircraft that would be using oil dilution still. For instance Buffalo Airways in Yellowknife Northern Canada with C46's and possibly DC3's(well known in the history channel). Turbo props don't use it.

Anyway thanks for the enlightenment everybody.

[bell]

Originally Posted by gamin

Flew Navy Super Connies (EC-!21) into Argentia Newfoundland on occasion in the winter. We always used oil dilution at shutdown pretty much like flygeezer describes. Engines were Wright R-3350 turbo compound radials. Always started nicely the next day.

Really? That's exactly what my friend Richard did.....we were just up there to running the targa Newfoundland and drove out on the old runway with the truck/911.....

[MT930]

I've heard the old timers talk about it in Alaska in the winter

I bet the procedure needed to be followed carefully, not to much fuel.

I bet you wanted it to evaporate off before selecting higher power settings, Had to effect engine life in a negative way.

If you had a lot of Oil / Fuel seepage in the lower cylinders on the big round engines would it blow jugs off starting them ?

The practice makes sense to lower the viscosity, it just sounds crazy to add fuel to the oil. 50 Wt oil is like peanut butter at -10F

Unbelievable what you can learn here.

[944Larry]

I flew a 1200 HP bull thrush and owned a Sikorsky S55 and they both had it. But living in the South I never had occasion to use it.

[Mrmerlin]

I flew a Cessna 310C with tuna tanks it had the oil dilution system for cold starting

[tevake]

Originally Posted by bell

” hey man......how many cylinders you got in that thing?”
”112.....”
”.........”

Yep That was what I was thinking. Plus , what a chore to change the plugs. Those aren't twin plugged are they?

Cheers Richard

[KNS]

gamin,

Could you post some pictures of the Connies you flew - pleeeze....

[FLYGEEZER]

All reciprocating aircraft engines use twin ignition (two plugs per cylinder). On round engines,winter & summer, the procedure was to "hand turn" the propeller several times to clear & check for liquid lock before starting. If a lock is discovered, removal of the front spark plug would clear the oil from the lower cylinders. Work intensive stuff!

[MT930]

Originally Posted by KNS

gamin,

Could you post some pictures of the Connies you flew - pleeeze....

Please +1

[romad]

Now thats a cockpit, you flew that beast..... actually have wear on the rudder pedals.

[FLYGEEZER]

Thanks romad, the old guys that flew them alwas said ; the cockpit was so narrow the pilot could get sun burned on both arms- Got any pictures of the really busy part of the cockpit, the flight engineers station?

[gamin]

Boy, got the Connie buffs awake. I do remember the "3 pieces of tail" joke. Wish it were true. Don't know Howie Price. that's a good cockpit photo. Very narrow. We adjusted the yaw trim by looking out the forward windscreen at a string attached between the radome and fuselage at the center seam. Adjusted trim till string was straight aft. High tech. Only had 72 cylinders.
18 in double row configuration and 3400 HP each. 3000 psi hydraulic system. Spring a leak and fluid gone in a hurry. I have very few photos of the Connies I flew. Couldn't take pics due to sensitive operations. True. Got a lot of instrument time since we didn't fly very high and it seemed like we were always in cloud. Lots of night hours. Got a lot more memories. Not enough space here. My eyes are misting up. I really miss those old birds.