Fuel drain not draining?

[StinkBug]

When I got my plane in January I noticed that it sometimes took a few seconds before the fuel selector drain would actually drain any fuel, but figured it was normal as I had no prior experience. Now it's not draining at all. I'm thinking there must be something clogging the drain as it was draining before and now if I hold the ring up long enough the drain will be wet, so something is trying to come out. Anyone know how difficult the drain is to inspect/clean, and if there's something specifically I should check? 

 

68 C model BTW.

[ken66770]

When I first bought my 65C, I thought it wasn't draining, even pulled and cleaned the filter a couple of times. I finally discovered that I just wasn't pulling hard enough. Now, I pull the ring until it feels like it has stopped, then pull some more. It won't break. Maybe. YMMV.

 

BTW, when the fuel drains using the inside drain, it drains the sump from the tank selected, i.e. left/right. It doesn't seem to drain anything with the selector in the off position. It's not difficult to inspect/clean the filter, but it wouldn't hurt to have your local A&P show you how.

 

Ken

[Guest]

It's easy to disassemble, you will have to remove the left belly fairing behind the firewall, beside the left nose gear door. Be sure that when you reassemble it you follow the instructions in SB 200

http://www.mooney.com/wp-content/themes/mooney2014/force-download.php?file=http://www.mooney.com/wp-content/uploads/2014/03/sbm20-200.pdf

Clarence

[Yetti]

Turn the Fuel to OFF.   You will need to have the gear door swing in to get the the screws next to it.  So you have one bolt to remove on the gear door link arm.   A bunch of panel screws.   One wired bolt in the bottom of the selector.   It will all come off.   LASAR has the screen gasket.  bonus points for straightening the holes in the access panel. probably want to drain some fuel out of each tank while everything is apart.

[Shadrach]

Who ever does this job should be an A&P or supervised by one and will need to have safety wire plyers and the ability to use them.

[Hank]

And be careful, I don't think anyone repairs these any more, either.

[N201MKTurbo]

Just pull the ring up and down a zillion times and see if it clears itself.

Like Clarence said it is easy to take apart and fix, I wouldn't,t worry about it. Even if you have to pay someone to fix it it won't be much.

[RobertGary1]

I had Lake Aero rebuild mine a few years back just because. If the selector jams from old degrading seals your day will be sad.

There is a screen in there that must be inspected at annual along with the filter in the servo.

-Robert

[StinkBug]

I have an A&P who is pretty happy to supervise me, as he knows my skillset. I build custom vehicles from scratch for a living, so wrenching is not an issue. I am not an airplane mechanic though, so when it comes to systems not found in the automotive or racing worlds I like to research. He's also not an MSC, so sometimes I've found that doing my own research can help him on the Mooney specific stuff. I'm betting this screen was not checked at the last annual, since that was right before I bought the plane just a couple months ago.

 

For clarification though, are you guys saying that I'll need to remove the entire fuel selector valve, or is it just a fitting on the drain side that has the screen? Just trying to figure out how involved this is gonna be so I can schedule hangar time accordingly.

[StinkBug]

When I first bought my 65C, I thought it wasn't draining, even pulled and cleaned the filter a couple of times. I finally discovered that I just wasn't pulling hard enough. Now, I pull the ring until it feels like it has stopped, then pull some more. It won't break. Maybe. YMMV.

 

BTW, when the fuel drains using the inside drain, it drains the sump from the tank selected, i.e. left/right. It doesn't seem to drain anything with the selector in the off position. It's not difficult to inspect/clean the filter, but it wouldn't hurt to have your local A&P show you how.

 

Ken

 

Hmm, good to know. It feels like it hits a pretty solid stop when I pull the ring, but it doesn't take a lot of effort. Guess I'll try pulling a bit harder next time and see what happens.

[Nemesis]

Dallas,

 

I would not pump the drain ring open and closed a bunch of times trying to clear it !!! There is something in there that is preventing fuel flow. The entire purpose of that pull ring and the fuel sump is so that you know fuel is flowing freely from both tanks. If it is clogged, then get the FOD out of your fuel system!! If you happen to knock it loose without inspecting, where is that crud going to go, to the screen or worse to block a tank line?

 

It is an easy job. First, turn off the fuel from the fuel selector. The worst part is removing and reinstalling the belly panel immediately behind the nose gear on the left side. After the panel is off, you will find an alum drum / tank about 2" dia and 4" long with a single bolt in the center. Cut the safety wire, remove the bottom bolt, and don't forget to put something under to catch the bit of fuel that will come out.

 

The center of that bolt assy is where the fuel drains from when you pull the ring. Clean out what ever crap is in there. Carefully pull the screen from the center shaft and blow it out or clean it up as well. Inspect with lights and mirrors as necessary. There are o-rings for the center shaft as well as the can. If I remember correctly, one is easy to replace and the other is impossible - not sure. Take a look at the rim of the can and notice that there is a small notch. There is also a key in the seat area when you go to reinstall the can. Be sure they are aligned before you put on the nut. I don't remember the torque value for the nut. Check for leaks and proper fuel flow from both tanks. Reinstall the safety wire and belly panel and you are done.

 

Dave

[StinkBug]

Thanks for the detailed response Dave. I think I have a pretty good picture of what you're talking about. Sounds very similar to the float bowl on some of the carbs I've worked on. 

[Guest]

I have an A&P who is pretty happy to supervise me, as he knows my skillset. I build custom vehicles from scratch for a living, so wrenching is not an issue. I am not an airplane mechanic though, so when it comes to systems not found in the automotive or racing worlds I like to research. He's also not an MSC, so sometimes I've found that doing my own research can help him on the Mooney specific stuff. I'm betting this screen was not checked at the last annual, since that was right before I bought the plane just a couple months ago.

 

For clarification though, are you guys saying that I'll need to remove the entire fuel selector valve, or is it just a fitting on the drain side that has the screen? Just trying to figure out how involved this is gonna be so I can schedule hangar time accordingly.

Once you access the selector valve you will find a bolt in the centre of the bowl, remove the safety wire from the bolt. There is also a large nut on the side which connects the drain tube to the drain fitting, back this nut off, now remove the bolt, the lower cover should now come off exposing the screen, the gasket and the drain plunger.

From here you should be able to find you trouble. Remember treat this like glass they don't make them any more.

Follow the link above when torquing the bolt, more than one has been ruined by over torquing thr bolt.

Clarence

[Hank]

"Treat it like glass" is great advice! I think mine has a large glass part, as well as being unsupported and no longer produced.

[Yetti]

probably about an hour job at most.  Nothing hard.  Mine is currently apart, I will take pictures.   You may want to pre plan and order the gaskets.  You could have them in several days if you call today.

[Yetti]

"Treat it like glass" is great advice! I think mine has a large glass part, as well as being unsupported and no longer produced.

If it is the one I am thinking of you can get that at the tractor supply store.

[RobertGary1]

If you do find any debris on that screen stop. It's not normal to clog up. In 15 years I've never actually seen anything on it. You'll need to clean the servo screen and inspect the whole system. It's not normal to have that much debris in the system. It's probably more likely a mechanical issue and the unit needs to be repaired.

-Robert

[StinkBug]

probably about an hour job at most.  Nothing hard.  Mine is currently apart, I will take pictures.   You may want to pre plan and order the gaskets.  You could have them in several days if you call today.

 

Do you have part #s for the gaskets? Do you just order them from Mooney directly?

[RobertGary1]

Have you by chance sealed your tanks recently? I've seen debris caused by recent sealant applied.

 

-Robert

[StinkBug]

I haven't, and the log books dont show anything too recent. I've only had the plane 4 months.

[RobertGary1]

This is certainly cause for concern. Its not at all normal for the collator to clog.

 

-Robert

[carusoam]

Something to consider...

If you have the original non SS filler necks... The piece that the fuel cap seals into...

You may see it starting to rust. Small black specks will sluff off and show up in odd places...

1) rust particles will keep the O-rings from sealing properly allowing water entry into the tanks...

2) rust particles will keep the seal on the fuel sample valve from sealing allowing fuel to drain out after you get a sample...

3) rust particles will sit on top of the strainer until they are small enough to fall through. Then they collect in that valve as well. The problem here is it either drips after use or nothing comes through...

Visually inspect the filler necks at the top of the tank. These parts have been made from SS for a while. They are a small cost to buy and install. But well worth it.

The mild steal originals will continue to rust until a hole forms allowing all kinds of moisture into the tank...

Are you tied down outside?

65C experience...

Best regards,

-a-

[Yetti]

I called Lasar parts and they knew just what I was asking for   http://www.lasar.com/about/contact.asp

[Nemesis]

Thanks for the detailed response Dave. I think I have a pretty good picture of what you're talking about. Sounds very similar to the float bowl on some of the carbs I've worked on. 

 

True, it is similar to a float bowl in that...

-on a carb, when you remove the center bolt it usually exposes the high speed jet.

-on the airplane, the center bolt is from where the fuel drains.

 

Of course there is no float inside, just empty space and a very fine screen.

 

Dave

[StinkBug]

Well it turns out Ken was the one that had it right all along. I went to the plane today all prepared to start pulling panels, and when I pulled the ring, then pulled a little harder than normal, fuel came pouring out. It didn't really feel like the ring moved any more than usual, but just a bit of extra pull and fuel flowed just the way it should. Guess I've just been doing it wrong. I like fixes that are this simple. I'm also happy to have learned a few things from this thread that may be useful in the future.

 

Thanks everyone!