Sport Pilot Talk

bitten192 · Joined: 21 Dec 2009 Posts: 61 Location: RICHLAND WA USA

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

Ernie

drseti · Joined: 28 Nov 2009 Posts: 1390 Location: Lock Haven PA

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??

bitten192 · Joined: 21 Dec 2009 Posts: 61 Location: RICHLAND WA USA

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

roger lee · Posted: Tue Oct 18, 2011 7:13 pm Post subject: Valve cover

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.

drseti · Joined: 28 Nov 2009 Posts: 1390 Location: Lock Haven PA

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.

bitten192 · Joined: 21 Dec 2009 Posts: 61 Location: RICHLAND WA USA

[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

drseti · Joined: 28 Nov 2009 Posts: 1390 Location: Lock Haven PA

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.

comperini · Joined: 24 Feb 2008 Posts: 152 Location: California

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.

bitten192 · Joined: 21 Dec 2009 Posts: 61 Location: RICHLAND WA USA

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
CFI
LSRM-A

bitten192 · Joined: 21 Dec 2009 Posts: 61 Location: RICHLAND WA USA

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

drseti · Joined: 28 Nov 2009 Posts: 1390 Location: Lock Haven PA

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.

roger lee · Posted: Wed Feb 01, 2012 9:23 pm Post subject: Oil Tube leak

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.