Oil on the cowling near the spinner

[firelog1101]

I bought a 1978 M20J back in December, haven't had any issues with it until recently I've noticed a small amount of what appears to be oil on the cowling near the spinner on the cowling.  The engine and prop has 100hrs on it and was new since the previous owner had a gear up 5 year ago.  I had a mechanic do an oil change and see if there's any oil leak he can find, he wasn't able to find anything on the runup in the shop and said to fly it around.  Still have the small leak that I notice after shutting down, the actual oil amount doesn't seem to go down by an appreciable amount.

 

 

 

 

 

 

 

 

 

 

Edited March 24, 2023 by firelog1101

[Rick Junkin]

@firelog1101 Check the top of your prop governor for a leak at the pressure relief valve nut. I had similar symptoms when mine was leaking. If that’s the problem, here’s the  McCauley service letter for the field fix to replace the o-ring. Takes a $5 o-ring, some teflon tape and about 20 minutes max. No need to remove the governor for rebuild, which is what most shops will probably recommend.

Cheers,
Rick

McCauley S.L. 1998-22A.pdf

[N201MKTurbo]

1 hour ago, Rick Junkin said:

@firelog1101 Check the top of your prop governor for a leak at the pressure relief valve nut. I had similar symptoms when mine was leaking. If that’s the problem, here’s the  McCauley service letter for the field fix to replace the o-ring. Takes a $5 o-ring, some teflon tape and about 20 minutes max. No need to remove the governor for rebuild, which is what most shops will probably recommend.

Cheers,
Rick

McCauley S.L. 1998-22A.pdf 1.74 MB · 2 downloads

The J has the prop governor on the back of the engine. So it probably isn’t that.

[Rick Junkin]

5 minutes ago, N201MKTurbo said:

The J has the prop governor on the back of the engine. So it probably isn’t that.

DOH

My bad.

[M20R]

Prop seal. Had to change mine recently. Exact same symptoms.

[PT20J]

I would uncowl and check, but that’s usually the front crankshaft seal. A shop can replace it by removing the prop and seal and stretching a new seal over the flange with a tool.

[firelog1101]

Thank you for your input everyone, it is a McCauley prop. Do these have the red dye inside? It sounds like it doesn't show up on a ground run but will with a 30min flight.

[OR75]

Squared prop tip (C212) or round prop tip (C214)? 

[firelog1101]

It is the round tip c214. Also there is no window spray or puff whatsoever in flight. It's literally just that streak and a small splattering on that inlet

Edited March 24, 2023 by firelog1101

[PT20J]

2 hours ago, firelog1101 said:

Thank you for your input everyone, it is a McCauley prop. Do these have the red dye inside? It sounds like it doesn't show up on a ground run but will with a 30min flight.

@Cody Stallingswould know for sure, but I don't think the C214 is oil filled. 

Skip

[firelog1101]

Here are some more pictures comparing the cowling inlets on the left and right

 

 

 

 

[Guest]

Lift the top cowl off, run your fingers inside the starter ring gear support pulley and feel for oil.  A leaking from seal will deposit oil there.  Of course you should do this with the engine shut off!

[Cody Stallings]

On 3/24/2023 at 3:35 PM, PT20J said:

@Cody Stallingswould know for sure, but I don't think the C214 is oil filled. 

Skip

214 shouldn’t have oil in it, if it does then the hub is filling up with engaging oil, which isn’t good.

Is the oil coming from the base of the blades?

[carusoam]

@firelog1101 our prop guy left an interesting question for you…. (This sent a message to the OP)

Best regards,

-a-

[firelog1101]

No there isn't any oil from the base of the blades. The shop guys said the crankshaft seal is completely dry but could replace if I really wanted to. They're not really sure what it could be and have suggested having the guys at Lycon in Visalia CA look at it since they did the overhaul in 2017. They said the last shop it was at put some red silicon(?) on areas that were leaking, probaby voided the warranty even though it has 100hrs on it.They also said the leak seems minor and might be a waste to go after at this time...just surprising for a 100hr engine to have a leak like this, at least in my eye.

At this point I'm just going to wait for annual and have an MSC look into it.

[Guest]

31 minutes ago, firelog1101 said:

No there isn't any oil from the base of the blades. The shop guys said the crankshaft seal is completely dry but could replace if I really wanted to. They're not really sure what it could be and have suggested having the guys at Lycon in Visalia CA look at it since they did the overhaul in 2017. They said the last shop it was at put some red silicon(?) on areas that were leaking, probaby voided the warranty even though it has 100hrs on it.They also said the leak seems minor and might be a waste to go after at this time...just surprising for a 100hr engine to have a leak like this, at least in my eye.

At this point I'm just going to wait for annual and have an MSC look into it.

I don't know how sealing the edges for the baffles with silicone could void a warranty?

[Ragsf15e]

3 hours ago, firelog1101 said:

No there isn't any oil from the base of the blades. The shop guys said the crankshaft seal is completely dry but could replace if I really wanted to. They're not really sure what it could be and have suggested having the guys at Lycon in Visalia CA look at it since they did the overhaul in 2017. They said the last shop it was at put some red silicon(?) on areas that were leaking, probaby voided the warranty even though it has 100hrs on it.They also said the leak seems minor and might be a waste to go after at this time...just surprising for a 100hr engine to have a leak like this, at least in my eye.

At this point I'm just going to wait for annual and have an MSC look into it.

Just to make you feel better (or worse), the airflow in there is pretty insane, so that oil might be coming from somewhere unexpected.  Might want to widen the search…

[Yetti]

If you did a messy oil change.....  oil will come forward.   Might want to wash the engine and cowl.  Check the front oil seal for turning.  Fly some more.

[PT20J]

You could try thoroughly solvent washing the engine and ground running it until you get normal oil temp and then checking to see if you can see where it’s coming from. 

[MichMooney201]

I just resealed my prop and the oil residue I found before fixing had a spray pattern on the cowl from flight ...yours looks like it is leaking while sitting.  Clean it really good and run it for an hour and inspect again.  That doesn't look like a leak from flying from the prop...I also have a 78 J.