oil/oil seal question...help!

[Tom G]

My engine now has 170 hours since major gets 40psi on the oil pressure and overall runs great. That being said at the last annual (last month) we put in Phillips XC oil 20W50 weight. I flew this morning and when I checked the oil I noticed it was down to just over 3 quarts (7.2hrs since the change). I thought about it because the engine never seemed to use any oil at all. Anyway I flew it this morning for an hour and while tying down noticed a streak of oil coming up the top of the nose cowl and a fine mist of oil on the windshield. It looks like the front seal is leaking! I never had any noticeable leak before when I was using straight Aeroshell 100 (50wt). Since this is the first time I ever saw a leak like this and its also the first time I ever used multi-vis oil I can't help but think the two are connected.. I sure hope I don't need a new front seal..doesn't the case have to be split for that?! Any thoughts on this would be greatly appreciated..thanks

[VictorBravo]

Re: oil/oil seal question...help!

If my understanding is correct, the 20W50 designation means that the actual viscosity is 20 weight oil (THIN), that has some anti-wear and other ingredients that allow it to have wear/heat qualities of 50 weight oil.

So even if it has chemicals that fight heat and pressure AS IF it were a thicker oil, it is not a thicker oil.

So thin oil will leak out of more places obviously.

On a Continental, the "usual suspects" are the pushrod tube seals, the front case seal, and the crankcase breather.

As you point out, the location of the leak is a telltale of the front seal.

The good news is that you do NOT have to split the case to replace this. You do, however, need a mechanic who has done it before and knows the delicate techniques to get that seal out and in. If you have a tapered crankshaft it is a LOT easier, but it can be done on a flange shaft.

[Ron Babos]

Re: oil/oil seal question...help!

Phillips 20/50 xc has no antiwear additives and should not cause the problem you have. It's just coincidence that it happened the same time. Phillips is mineral oil with ashless compounds and dispersant additives to suspend dirt. It is not a detergent oil, as many people think. Aeroshell 15/50 is a semi synthetic and can be notorious in finding leaks as the synthetic will flow through smaller areas. Bottom line, your seal is toast. On that note, look to see if there is a groove in the crank where the seal lip rides. If there is, make a 1/16" spacer ring to put in behind the new seal to give it a new area to work on.
Ron

[VictorBravo]

Re: oil/oil seal question...help!

On that note, look to see if there is a groove in the crank where the seal lip rides. If there is, make a 1/16" spacer ring to put in behind the new seal to give it a new area to work on.
Ron

I like that! Clever!!! I'll be replacing my seal fairly soon, so your idea will be in the front of my feeble brain.

[N96337]

Re: oil/oil seal question...help!

Check your crankcase vent system carefully... I've seen those get a flex hose or something kinked at annual, or the end turned the wrong way when things get put back together... only takes a few minutes to check it all out, and if you don't find anything, it's not a biggie to replace that nose seal.
JH

[Tom G]

Re: oil/oil seal question...help!

thanks guys for your advice. i was greatly releived to hear that the case doesn't have to be split to do this.

i'll check the crankcase vent first though!

I'll let you know

[Pearson]

Re: oil/oil seal question...help!

Seal Schmeel!!! Put the straight 50wt oil back in and go fly!!

[robbie]

Re: oil/oil seal question...help!

Got my old seal out and I'm looking at the crank, thinking we should put a spacer behind the new seal.
My AP came down and looked it over and said "good idea".
Question, the I.D. has to be fairly close but the O.D. just about any thing.
I could use some tips on how to make it.
Are there any washers out there I could start with?

[Mark Julicher]

Re: oil/oil seal question...help!

Get a sheet aluminum or aluminum shim stock. I recommend .020 thick.
Nearly every airport I know has some tinker with a small left over piece of sheet metal. If not the case where you live then Aircraft spruce sells sheet aluminum and McMaster Carr sells sheets of shim stock in all thicknesses and metal types.

I would not recommend a metal other than aluminum - could introduce a dissimilar metal problem.

Cut out the washer you need with snips, drills, nibbler, file, sandpaper, whatever works for you.

[robbie]

Re: oil/oil seal question...help!

thanks for the suggestion Mark.
.020 you think?

[Mark Julicher]

Re: oil/oil seal question...help!

.020 is good .015 is OK too. I don't think I would go any thinner based on crank wear I have seen, and I doubt that you need any more than .020 to move the seal lip to a good spot on the shaft.

Let us know how it turns out.

[Hank Jarrett]

Re: oil/oil seal question...help!

Just a hint, it's easier to drill the hole first and then trim the OD. Just make sure you center punch first, next scribe the OD from the center, then drill the ID followed by trimming to the scribe line.
This is all obvious if you have done it before. Make SURE you clamp the .020 sheet down well (NOT WITH YOUR HAND!!!!) while drilling. If the bit grabs the sheet makes a great saw blade.
Hank

[asq]

Re: oil/oil seal question...help!

might want to check Continental SB M76-4 "Installation instructions for propeller shaft or crankshaft oil seals". Cured a real bad leak for me. Larry

[jdoran]

Re: oil/oil seal question...help!

This might be a dumb idea, but how about buying two seals, and modifying one to be the spacer?

It already is the perfect diameter.......

[freightpilot27]

Re: oil/oil seal question...help!

And when your completely finished installing the new seal and spacer, drain that phillips crap out and replace with Aeroshell W100.