Resurrecting a Lycoming O-540

[Electro]

I have an opportunity to buy a Comanche 250 which has not been flown or started in 10-12 years so the condition of the engine is a complete unknown. Other than boroscoping the cylinders, cleaning plugs and changing oil is there a recognized prepping procedure before trying to start the old girl?

[carusoam]

Electro,

Sounds like a great question for ComancheSpace...

Wait just a second... I’ll post a link...     @M20Doc

If you know doc’s other plane... this is really funny...

Best regards,

-a-

[RLCarter]

pre-oiling

 

[Guest]

I would borescope the cylinder to see if they’re corroded, oil the cylinder walls with a fine mist through the spark plug holes, pre oil the engine with a pressure pot connected to the front right oil gallery.  If you can’t get a pressure pot, you could build one out of a weed sprayer, some hose and fittings.
  
On second thought maybe you shouldn’t do it.  Once you work on and fly this Comanche you’ll never be the same and may want to sell your Mooney!

Clarence

[Electro]

Thanks for the oiling tip, Clarence. I'll see if I can put something together. Shh, the Mooney doesn't know about this yet.

[carusoam]

Bring flowers and a bottle of wine with the pre-oiler... see if she notices...

-a-

[A64Pilot]

it’s the cam of course that will be your biggest concern. I’d pull a couple of cylinders one from each side and get a look. That also lets you get a good look at the cylinders too.

Someone in my neighborhood is resurrecting a twin Comanche that hasn’t run in 15 or so years, they had rusted cylinders on the left engine but said the cam was good. I think they will know for sure in 50 hours, or so.

I would inspect the filter in 5 hours, then 15, and finally 50, after 50 I’d start to feel lucky.

‘The moment you find metal that will stick to a magnet, stop and find out where it’s coming from, if you catch it in time you may save a crank etc.

Put lots of oil in the cylinders and leaving the bottom plugs out spin it over several times with the starter to blowout all oil out before you put the plugs back in prior to starting.

 

Last edit. Good luck on getting the plug out of the case, sometimes they can be a real bear to get out, you can pre-oil from just about anywhere even remove the pressure sender and go in there if you can’t get the plug out

Edited March 27, 2021 by A64Pilot

[Electro]

  On 3/27/2021 at 5:28 PM, A64Pilot said:

it’s the cam of course that will be your biggest concern. I’d pull a couple of cylinders one from each side and get a look. That also lets you get a good look at the cylinders too.

Someone in my neighborhood is resurrecting a twin Comanche that hasn’t run in 15 or so years, they had rusted cylinders on the left engine but said the cam was good. I think they will know for sure in 50 hours, or so.

I would inspect the filter in 5 hours, then 15, and finally 50, after 50 I’d start to feel lucky.

‘The moment you find metal that will stick to a magnet, stop and find out where it’s coming from, if you catch it in time you may save a crank etc.

Put lots of oil in the cylinders and leaving the bottom plugs out spin it over several times with the starter to blowout all oil out before you put the plugs back in prior to starting.

 

Last edit. Good luck on getting the plug out of the case, sometimes they can be a real bear to get out, you can pre-oil from just about anywhere even remove the pressure sender and go in there if you can’t get the plug out

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Pulling a couple cylinders may be cheap insurance. Thanks.