912 VALVE COVER OIL LEAK

H. Paul Shuch is a Light Sport Repairman with Maintenance ratings for airplanes, gliders, weight shift control, and powered parachutes, as well as an independent Rotax Maintenance Technician at the Heavy Maintenance level. He holds a PhD in Air Transportation Engineering from the University of California, and serves as Director of Maintenance for AvSport of Lock Haven.

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bitten192
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912 VALVE COVER OIL LEAK

Post by bitten192 »

I have a valve cover leak. I plan to replace the seals. Is an oil purge required?

Ernie
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drseti
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Post by drseti »

I would think not, Ernie, because there's normally air around the rocker arms anyway. (Unlike the oil pump; when you rebuild that, you absolutely have to purge the system). OTOH, if you have the CPS purge kit, it's an easy process, so it couldn't hurt. If you replace the valve cover gaskets during an oil change, and pull the oil tank to clean it, you're going to do a purge anyway, so no extra pain there.

How much oil are you losing at the covers? And, are you sure it's the valve cover gasket, and not the pushrod tube o-ring??
The opinions posted are those of one CFI, and do not necessarily represent the FAA or its lawyers.
Prof H Paul Shuch
PhD CFII DPE LSRM-A/GL/WS/PPC iRMT
AvSport LLC, KLHV
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AvSport.org
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bitten192
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Post by bitten192 »

Not much of a leak. No drip, just a film on the lower edge of the cover. Noticed it a while ago. Doing an annual soon so planned to fix the leak while the a/c was down.

If you pull the tank and do not change the elevation of the oil tubes connected to the tank, why do you have to do a purge? An absent tank is just like an empty tank if you don't mess with the elevation of the oil lines. No? Yes?

eb
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Valve cover

Post by roger lee »

Hi Ernie,

I'm surprised you didn't ask this on the CT forum.

Many 912's have an ever so slight an ooze. It isn't enough to drip or make a mess, but enough to get on your finger. You have several options and anyone may fix it or not. First no oil purge is necessary.
You can try new "O" rings, apply a little Loctite 5910 on the "O" ring or put the valve cover on a flat surface with a little 360 sandpaper and move it around in all directions to flatten the cover surface and remove any high spots. You may end up doing all the above.

Last shot is replace the valve cover, but that's not a guarantee either.

Sometimes one of these works and sometimes not.
Roger Lee
Tucson, Az.
LSRM-A, Rotax Instructor & Rotax IRC
(520) 574-1080 (Home) Try Home First.
(520) 349-7056 (Cell)
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drseti
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Post by drseti »

bitten192 wrote:If you pull the tank and do not change the elevation of the oil tubes connected to the tank, why do you have to do a purge?
Ernie, didn't you learn in the Carpenter's course that logic has no place in LSA maintenance? :wink: The service instruction says that any time you break the system, you have to do a purge. Technically, as I read it, removing the drain plug does not constitute breaking the system, but removing the oil lines does. (Don't expect this to make any sense...)

In fact, any time I change the oil filter (which is to say, at every oil change), I do a purge. Maybe that's overkill, but remember that the new Rotax oil filter can't be pre-filled, so I figure what the heck.
The opinions posted are those of one CFI, and do not necessarily represent the FAA or its lawyers.
Prof H Paul Shuch
PhD CFII DPE LSRM-A/GL/WS/PPC iRMT
AvSport LLC, KLHV
[email protected]
AvSport.org
facebook.com/SportFlying
SportPilotExaminer.US
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Post by bitten192 »

[quote="drseti] Technically, as I read it, removing the drain plug does not constitute breaking the system, but removing the oil lines does. (Don't expect this to make any sense...) .[/quote]

Paul, when you drain the tank, you uncover the ends of the suction and return lines in the tank. What difference does it make if you then remove the tank for cleaning as long as you don't overly shake the oil lines or change their elevation. Just sayin...eb
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Post by drseti »

Logical, Ernie - but as I said before, since when does logic enter into anything lsa related? :?

This would make an excellent discussion for the lsrm group on linkedin. I'd be curious what the other mechanics have to say.
The opinions posted are those of one CFI, and do not necessarily represent the FAA or its lawyers.
Prof H Paul Shuch
PhD CFII DPE LSRM-A/GL/WS/PPC iRMT
AvSport LLC, KLHV
[email protected]
AvSport.org
facebook.com/SportFlying
SportPilotExaminer.US
comperini
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Post by comperini »

For normal oil changes, the line maintenance manual, and SI-912-010 do not require purging of the system. Yes, you could argue, that if you disassemble the oil tank for internal cleaning, you might want to purge the system, if there was any chance you got "extra" air in the oil lines while the tank was disassembled.
- Bob
Commercial pilot, CFI, DPE, Light Sport Repairman/Maintenance
http://www.sportpilotinstructor.com
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bitten192
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Post by bitten192 »

Thanks for the info Bob. By the way, your website http://www.sportpilotinstructor.com ,is the best compilation of reference websites that I have ever seen. Thanks again.

Ernie
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bitten192
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Re: Valve cover

Post by bitten192 »

roger lee wrote:Hi Ernie,

I'm surprised you didn't ask this on the CT forum.

Many 912's have an ever so slight an ooze. It isn't enough to drip or make a mess, but enough to get on your finger. You have several options and anyone may fix it or not. First no oil purge is necessary.
You can try new "O" rings, apply a little Loctite 5910 on the "O" ring or put the valve cover on a flat surface with a little 360 sandpaper and move it around in all directions to flatten the cover surface and remove any high spots. You may end up doing all the above.

Last shot is replace the valve cover, but that's not a guarantee either.

Sometimes one of these works and sometimes not.
I replaced the seals on #1 valve cover and fixed the my leak. Used a little 5910 as you suggested. I noticed (using my $69 harbor freight "Colonoscopy" scope) a little oil at the interface where the oil return tubes go into the back side of the cylinder head. The Illustrated Parts Manual shows no seals there. Are they just screwed into the head? I'm thinking it's not worth the trouble to pull the head to fix. Comments? (also posted on CT Forum)

Ernie
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Re: Valve cover

Post by drseti »

bitten192 wrote:a little oil at the interface where the oil return tubes go into the back side of the cylinder head. The Illustrated Parts Manual shows no seals there. Are they just screwed into the head?
That's my recollection from the CPS course, Ernie.
The opinions posted are those of one CFI, and do not necessarily represent the FAA or its lawyers.
Prof H Paul Shuch
PhD CFII DPE LSRM-A/GL/WS/PPC iRMT
AvSport LLC, KLHV
[email protected]
AvSport.org
facebook.com/SportFlying
SportPilotExaminer.US
roger lee
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Oil Tube leak

Post by roger lee »

Hi Ernie,

You are right there are no "O" rings there. Those are held in place by Loctite 648. They can be heated and removed then put back in place with the Loctite. If it is a tiny leak it may not be worth doing. Just keep an eye on it.
Roger Lee
Tucson, Az.
LSRM-A, Rotax Instructor & Rotax IRC
(520) 574-1080 (Home) Try Home First.
(520) 349-7056 (Cell)
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