Old Oil On Front Gear Doors

[MooneyMunnerlyn]

Hello,

I have a 1965 M20E and it has been dripping old black oil down the two front corners of the front gear door. Two oil changes ago I carelessly let a bit of oil from the oil filter spill down and I figure maybe that is all it is, but that was months and many flight hours ago. Any ideas on where this somewhat steady stream of black oil is coming from would be appreciated. I have linked a photo.

[carusoam]

Hey munnerlyn!

you mentioned the plane is new2U…

there are about a dozen places that the small Lycoming is know to possibly have drops from…

Get the bright light out…

and start at the top where there are seals, gaskets, and hoses…

simple solution to a common problem…

often, people find these things are ancient, and can use a nice replacement…

See if you can identify the valve covers… their gaskets may still be ancient cork… their screws could be equally ancient and have uneven torque applied..

nearby is a group of oil return lines that drain the valve box area… lots of hose clamps that may be ancient…

 

The M20E makes a great forever-plane!

Welcome aboard and best regards…,

-a-

Edited February 27, 2024 by carusoam

[Skates97]

Welcome aboard, and it doesn't take very much oil to show up like what you have. It could be something new, but still could be oil finding it's way out from what was spilled during that oil change.

[EricJ]

Mine does that, too.    If some oil gets spilled it'll show up on the front of the gear doors for a while.

[hammdo]

I see that often. I don’t have high oil usage so it’s just the life of a lycoming. I did notice your gear door heim linkage looks like it has a bent rod…

-Don

[Ragsf15e]

3 hours ago, MooneyMunnerlyn said:

Hello,

I have a 1965 M20E and it has been dripping old black oil down the two front corners of the front gear door. Two oil changes ago I carelessly let a bit of oil from the oil filter spill down and I figure maybe that is all it is, but that was months and many flight hours ago. Any ideas on where this somewhat steady stream of black oil is coming from would be appreciated. I have linked a photo.

That’s a really common sight and that’s not much oil.  Impossible to tell where it’s coming from.  The return lines from the valve covers are common leak points. As are stuff on the back around the accessory pads.  There’s also likely oil coming out from your breather and maybe the sniffle and/or fuel pump drain.  You’ll need to clean it real good and see if it comes back to the point where you want to really look for it.  They all leak a little (even the people who say they don’t).

[DCarlton]

I had a small leak in a T fitting associated with an oil pressure sensor 2-3 years ago.  I’m still cleaning up the oil.  Haven’t found any other leaks and my plane uses very little oil but it makes me keep looking.  

[Ragsf15e]

Any “leak” that uses a measurable amount of oil is likely a gusher. It only takes a dribble of hot oil to spread a very thin, very messy patch along the gear doors or belly.  Less than can be measured on our caveman dipstick for sure.  So just be careful thinking “I have no leaks” because I only burn 1qt/7 or whatever.

[phxcobraz]

I get something similar. It comes out the breather right by the cowl flap and blows back towards the front gear door hinge. It doesn't take much oil to make a mess.

[ArtVandelay]

I had a similar leak, turned out to be a cracked case close to the alternator.

[Danb]

I’d first clean the nose gear area so then you’ll have a better idea when and maybe where it’s coming from. 

[LANCECASPER]

On 2/26/2024 at 6:35 PM, MooneyMunnerlyn said:

Hello,

I have a 1965 M20E and it has been dripping old black oil down the two front corners of the front gear door. Two oil changes ago I carelessly let a bit of oil from the oil filter spill down and I figure maybe that is all it is, but that was months and many flight hours ago. Any ideas on where this somewhat steady stream of black oil is coming from would be appreciated. I have linked a photo.

 

Consider it a feature - keeps those him bearings lubricated 

Mooneys have a habit of wanting to mark their territory for dominance, attempting to keep away the occasional Piper and Cessna. 

Get some mineral spirits and put it in a spray bottle and clean it up and see where it's coming from.