Prop hub oil leak

[b5c1flyboy]

I was flying my 1835 S-II a few weeks ago when I noticed my canopy was getting harder and harder to see through. I landed and found that oil appears to be leaking from just behind my prop hub. I'm not exactly sure what prop hub I have, but I will post some pics of it as soon as I can. I was reading that with some hubs there is no front seal and there is an "oil slinger" instead. If this is what I have, could it be as simple as me accidentally overfilling the oil? Or do I have a harder (more expensive) problem. Thanks for your help.
Todd

 

[mike1]

the first thing to look at is your crankcase vent system. it needs to vent all pressure out of the case, or the oil from the front bearing Will blow out of the case instead of draining back inside as designed. check for kinks or an obstruction. blow through the vent tube to check for full flow.

 

[b5c1flyboy]

I tested the crankcase vent system today and I don't think it is the problem. I blew through it in both directions, and didn't feel much resistance. I still think I may have overfilled the oil the last time I added some. I'm thinking it's not leaking on the ground because it is in a 3 point attitude, but in a level flight attitude the oil is at the same level as the crank. Is this possible? I attached a picture of the prop hub. could someone tell me what kind it is and if it could be part of the problem? The wider silver part between the hub and the case rotates with the crank. I'm not sure if it is supposed to, but I never payed any attention to it before it started leaking.
Thanks,
Todd

 

[Gaston]

Todd
it is most probably due to overfilling the crankcase...
If you check the oil level after the engine was running it allways read low.so if you top up at this time it will be too much...
may be this is due to the fact that all the oil trapped in Valve covers and pushrod tubes takes a while to drip back to oil pan...
this overfill reduces the airspace in the case ,so increasing oil spill via the vent and/or hub...
this associated with a leaking ring on a few pistons may be your situation...
check oil level when cold,and make sure your qty marks on the dip stick are realistic,and also proceed for a compression test just to make sure...
leaky valves may cause low compression but it won't cause pressure in the case

Hope this helps

Gaston

 

[mike1]

Todd,
i am not familiar with your prop hub, but the wide silver part looks like a seal
holder. the metal holder should be stationary in the case and it has a rubber seal which lets the hub rotate inside it. can you hold that part stationary and still rotate the prop? --with ignition disabled or plugs out, of course.

 

[b5c1flyboy]

Thanks, Gaston. One of my problems is that the dipstick doesn't have any qty marks on it. It just has some lines that don't really have any value to them. I'm almost due for an oil change so I'll just change it and make the qty values on the stick as I go. As for the seal holder, it does rotate with the prop, but I can hold it stationary if I turn the prop. It feels like it is making a good seal on the crank and the case.
Thanks,
Todd

 

[splischke]

Your seal rotates? I have a 1600cc VW with a shrink fit hub. The oil seal is similar to what I see in your picture. Per GPASC instructions, the seal is bonded to the case with JB Weld. See: http://www.greatplainsas.com/iphseal.html

-Scott

 

[Gaston]

Todd
Make sure you jack up the tail for draining the oil ,so all is drained...
when adding oil after change ,usually the first litre or quart (near the same)
don't show on the stick...
then you add another litre or quart and wait for it to settle down,and then mark the stick with 2 marks with a center punch....
then you add a third ,wait and make a 3 spots mark...
now next time you will know exactly what you have in it ....
then do the level test after the engine was used ,and you will see How low it shows when it is full of oil but recently used......


Gaston

 

[mike1]

Todd,
congratulations, you have found your oil leak. it is coming out between the seal housing and the case. do what Scott said and you will be oil tight. be sure to degrease completely.

 

[b5c1flyboy]

Thanks everyone for the help. I'll try the JB weld as soon as I can get to the airport with some spare time. I'll let you know the results.
Thanks,
Todd