try to fix the problem of low oil pressure

[witek]

Hi Guys,

I need your support concerning my engine which is IO360 M1A ? Catto constant speed propeller.

I try to fix the problem of low oil pressure 45-55 PSI in flight.
One idea came from my friend and is related with the governor adapter. On the attached photo:

https://www.dropbox.com/s/wxq195h7ft...08.18.jpg?dl=0

you can see the current status. A part of oil pressure can be reduced by 2 holes on right and left side of the gasket (holes are not fully covered by the current gasket).

The idea from my friend is to close these 2 holes by the full coverage gasket ? to lose the oil flow across this part of the engine.

Is this good idea?
Any negative consequences for engine?

Thank you in advance.
Witold

[mahlon_r]

Definitely your problem. The hole on the right is open to the lifter oil gallery. You are dumping that oil pressure to the hole below the gov. drive spline which is a drain back to the engine. So in essence you have a fixed oil pressure relief valve in addition to the real relief valve on the engine. That port normally feeds the prop governor.
The port on the left would normally take governor oil pressure to the prop and has no lubricating effect on the nose bearing.
So you should have both blocked off for a fixed pitch engine. as long as the rear plug in the nose bore of the crankshaft is pierced or missing. If by chance it is installed and not pierced you should leave the left port so that it will bleed the engine oil pressure from the nose bearing back through that port to the drain below the drive spline. If there is no bleed for the nose bearing oil pressure either through the missing rear nose bore plug or a hole in that plug if it is installed or back through that left gov. pad port you could blow the front crankshaft plug out of the engine and cause a massive oil leak.
Good Luck,
Mahlon

[witek]

Thank you very much for detail explanation. I know the Lycoming SB regarding the conversion of constant speed crankshaft to fixed propeller but unfortunately, I don’t know if the rear plug was removed or not. I bought the crankshaft new and on the specification, I can see it is prepared for constant speed propellers and it probably means the plug is installed.
My engine has 700 h since factory new and only the crankshaft was exchanged due to prop strike on previous aircraft (DA40). Now on my RV7A only 10 hours (test phase).
Do you know a method how to check if the plug is installed or not without de-assembling the engine?
If there is no method to check it I will apply the method you described in your post. I will prepare a new gasket which will close the right hole and the left remain opened.

Thank you,
Witold

[mahlon_r]

It doesn't hurt anything to have the rear crank plug in and vented or out with the oil pressure vented through the gov drive pad. Two vents is just as good as one. So, if not sure about the rear crankshaft plug just vent through the gov drive pad as described. Or even use a small grinder tool and cut a grove in the drive pad it's self to accomplish the bleed from the left gallery to the center area. Some of the newer drive pad covers have a groove already cut in them to accomplish this. Older ones dont'. so don't rely on the groove being there without checking. I have a picture of the gov plate with the relief groove machined into it, if you would like a visual. Just PM me with your email address and I will send it to you.
Good Luck,
Mahlon

[brad walton]

Catto constant speed prop? Please elaborate

[titanhank]

Show us some pics of the catto constant speed prop. I see an upgrade in my future..

[witek]

Hi Guys,

Of course mistake from my side.
Catto 2 blade propeller (fixed) - the good one :-)

Witek

Originally Posted by titanhank

Show us some pics of the catto constant speed prop. I see an upgrade in my future..

[titanhank]

I was hyperventilating when i read catto CS.. i know he is working on it, but who knows when it will be available. I hope by the end of the year. I am planning an rv200 from whirllwind if not.