fuel valve [Archive] - SuperCub.Org

08-15-2002, 08:01 PM

What's up with the stock fuel valve on the PA18. I see that Univair sells a PMA replacment valve.

The valve on my PA18 is really stiff, and I read somewhere that the stock valve needs a rebuild every 2 years.

Sept 7 update. Installed a Univair valve today. Hard to install, but it can be done with the fabric on. Much nicer valve than the original. Thanks for all the good feedback. :D

SuperCub MD

08-15-2002, 08:54 PM

This has been discussed elsewhere, I don't remember where. The Univair valve is a completely different design, and is worth the money. The stock valve does need a teardown, clean and lube every once in a while, and will never work as well as the Univair.

cubdriver

08-24-2002, 10:50 PM

Any reports on the new valves from Alaska Cub Drivers?

If they hold up to the frigid weather there, they are no doubt a good mod.

My brass valve requires disassembly, cleaning and lubrication every 50 ours or it gets hard to turn.

Rick Sanson

08-26-2002, 09:46 AM

It's annual time and fuel valve inspection/lube time for me. While my detetnts are good still I would prefer not to tear the thing apart <<again>>.

I suspect that the Univair valve "ya'll" are refering to is not in the PA18 Parts Manual.

Anyone have the P/N???

Thx

SuperCub MD

08-26-2002, 10:15 AM

P/N U491-947K

It comes with a spacer, hardware, and short 90 degree fitting to allow it to be installed in place of the original without modification. They work here when it is well below zero, I'll take one to AK for you cubdriver, to verify that it will work there also.

Glad you survived your trip Rick, have Univair throw in a calalog and price sheet when they send your valve.

Rick Sanson

08-26-2002, 02:36 PM

We did surive quite well Mark! Thanks to you and Kenny for the hospitality and the fuel burn! We very much appreciate it!

Road America is a great track we had nothing but fun! Having never been there and seeing it from the air me to understand the layout quicker. We didn't win the race but then again we didn't expect to! :multi:

(You'd be surprised who fast a new "Club Car" golf cart can go after some "minor" field tweaks! Good thing we had some spare gas shocks and "Z" rated golf cart tires!)

I expect that next year I'll make the SC Fly-in! I've not done the Oshkosh thing yet because I'm afraid of something else to cram into summer but the SC fly-in is now a "gotta-do" event and I may as well throw in Oshkosh as a side event.

None the less, thanks for the ride! Be sure and tell Kenny that Kim appreciated it too and please tell Rolly (sp?!?) I'll buy his cabin. I'm looking to move north somewhere anywho!

Thanks Mark!

BTW, I posted the pictures of your strip in the New Holstein Photos area!

SuperCub MD

08-26-2002, 05:57 PM

Rick,
Thanks, for showing pics of my muddy Cub. Next time bring that high octane S-Cub along, your welcome anytime. If the cabin does come up for sale, I'll let you know. I'll let Kenny know Kim enjoyed the ride, Kenny and I flew together earlier today, and will again in the next day or two I'm sure, (the weather has been Indian Summer type beautiful, and looks like it will continue).

Crash

08-26-2002, 11:25 PM

The $200.00 Univair replacement valve is made in Germany and has a straight fuel shunt with O rings for seals between the three ports (Left, Right and Engine) and spring loaded balls for detents. The Piper valve has a tapered brass shunt in a tapered brass body that uses "friction fit" to seal between the three ports. The fuel lube keeps it free and turning. When the fuel lube (thick special fuel resistant grease) goes away it gets stiff to turn. This happens in about 150 or so hours of flight. The detents are a washer with notches in it and some pins as I recall. It is a bit of a pain to change out the valves with the fabric on. Some of those old fittings can be tough to get off and can be a leaking problem in reassembly. I would always install the new style valve at rebuild. If you have a long time to rebuild you can do it, it's just a pain. Crash

Lawn Dart

08-27-2002, 06:54 AM

I considered rebuilding my valve because the stem seal was leaking and the detents were gone. When I got the valve apart, I discovered that the counterbored washer that rides over the detent washer was installed upside down, it?ll disable the dentents in that configuration. Simply flipping the cupped washer was an easy fix for the detents but the stem was so corroded that no O-ring was going to seal on it, also, the tapered cock assembly was so galled that it?s been running on ?both? with no ?off ? position possible.

Time for a new valve. I went with the Univair part # U491-947K, $213.09 + shipping.

Now I gotta agree with Crash on this next part, except to say that it?s not really a bit of pain to change, it?s a REAL #$%&^* PAIN TO CHANGE. I got mine in and my A&P refused to sign it off because I used teflon tape on the threads on the 3 fittings that go into the body and the Tee that goes into the elbow. He doesn?t like the stuff and insisted that I pull it apart, clean it up and use some super duper honey like stuff that?s approved for av-gas. Got it in the second time and guess what? The threads are leaking! (gave him that look that the wife gives me, no words required) Got it back out, tightened all the fittings one turn, got it back in. Now the fuel lines won't line up with the flair fittings. Can?t simply adjust the fittings because their too damn tight and there?s no room to get a wrench in there! Out comes the valve, adjust the fittings, in goes the valve and finally no leaks. Did I mention that I?m dumping the fuel tanks each time?

Now that I?ve removed all the Band-Aids from the back of my hands, I gotta say that the new valve is very smooth, the detents are positive, and the need to rebuild has been eliminated.

Yeah, I?d do it again, I recommend the Univair valve, It's worth every bit of the pain that it takes to change it.

T.J.

08-27-2002, 12:00 PM

Cavy:
Yep, been there done that! Its a Bitc@! Your A/P is correct, never use teflon tape on fuel fittings. They have a habit of shedding small pieces which then plugs stuff up, down stream.

Rick Sanson

08-27-2002, 01:11 PM

Obviously to drain the tanks, remove stock valve, inspect, repair as required and re-install is a pain in itself.

My questions are these:

Are the fittings in the same orientation?

Is it essentially plug and play or are the fittings on the new valve oriented differently than the stock valve.

Does the Univair valve attach to the airframe using the same tabs or do the tabs require modification???

What additional work is required??

I would think it would be a direct replacement and I would rather learn from the pain of others than to be bitten myself!

Any help is appreciated!

SuperCub MD

08-27-2002, 01:26 PM

A spacer is included with the valve so it is orietated the same, and a drawing is included, no modification to the tab is required, and all the fittings should be very close. In the world of modifications (even with fabric on), this is really not a big deal, and the new valve is well worth the money and effort.

Cavy, I applaud your mechanic for having the balls to make you take it back apart and do it correctly (teflon tape should never be used). A important lesson, if you expect him to sign off on your work, ask first, and do it right. And a word of caution, don't give him that look that your wife gives you, your lucky you didn't get hit with a really big wrench.

Lawn Dart

08-28-2002, 02:50 PM

Rick
It?s pretty much the same as if you were to remove and reinstall the stock valve. Yes? it?s Plug & Pray (play), no modifications required. It?s just one of those little ?fiddle and fit? type of jobs that you?d hate to have to pay an hourly shop rate for. Take a close look at your stock valve before you start to assemble the flair fittings on the new valve and try to get them as close to the same position (on the new valve) as they were on the old valve. Getting the four female flared fuel lines in the plane joined with the four male flared fittings on the valve, in a neutral or ?no bind? condition, is the ?fiddle & fit? part. MD is correct in saying that it?s not that big a deal. More of an exercise in patience.

MD
You?re absolutely correct about my A&P. I didn?t know that Teflon comes apart in Av-Gas and what you don?t know?you don?t know! The fittings in the old valve were installed with Teflon tape so I just copied what I saw.
This is a once in a lifetime opportunity for this pup to learn from an old dog. He has zero tolerance for the ol ?extra sealant instead of a new gasket? type of work, and for that I really appreciate this guy and the stuff he?s teaching me. We both learned from this installation and now we sit down and ?pow-wow? before the first wrench comes out of the tool box.

Stay tuned for future FUBAR?s from Cavy.

SuperCub MD

08-28-2002, 09:11 PM

Thanks for the info Crash, Didn't know the valve was made in Germany, no wonder it works so well. And Cavy, I should have remembered that your mechanic was a seasoned old salt. A young buck would have whacked you with a wrench, a well seasoned old salt would just doubled your bill instead.

cubdriver

08-28-2002, 09:20 PM

I have heard that installing the Univair valve will eliminate the fuel valve A.D.

??

Rick Sanson

08-28-2002, 09:36 PM

Unbeknownest to me (until today) the stock valve only needs to be removed and inspected IF it isn't operating properly. I thought that there was a requirment to disassemble, inspect and repair as required every n numbers of hours or years.

I thought wrong! As my valve is operating properly I ain't messing with it!

Thanks for the info!

Lawn Dart

08-28-2002, 09:51 PM

Beings were going on with this, I gotta ask. Seems this topic was elsewhere but can?t find it.
I believe the valve is made by the Allen company and I see that they also make the same three port valve that we?re using but it has a ?both? position instead of the two ?off? positions (Aircraft Spruce part # 05-29525). For us ex-spam can drivers this could be a life saving position. OK, I admit that if you can?t remember to switch tanks you?re considered to be a moron but this ?distracted and habit built? moron might just land with a fuel starved engine and a full tank on the other side. Is there a problem with running the ?both? type of valve?

Cub junkie

08-28-2002, 10:14 PM

I bought the replacement valve from Univair and it is an Allen made in Ravenna,OH according to the box. it is a very nice valve.

T.J.

08-28-2002, 11:59 PM

delete

Crash

08-29-2002, 02:00 AM

Bought mine a while back and the box it said made in Germany on it. Univair might have changed suppliers since that time. You modify it the same way as the stock valve for Left, Right and Both positions. You need to be careful taking it apart. There are all kinds of warnings not to take it apart. It's no big deal, just catch the balls and springs in a rag under the valve when pulling it apart. Go slowly, stuff flys everywhere if you jerk it apart too fast, not that Crash would ever do this. The factory fuel shunt is drilled out in an "L" shape. You just drill it through to make a "T". Watch how you drill it so the fuel selector pointer points the right direction when it's done. I made mine point striaght up for Both (take off), straight down for Off (stay on the ground), forward for Right tank and back for Left tank. Cubcrafters has the STC for the headerless "Cessna" style fuel system in a PA-18. They only have it approved for 18 gallon stock tanks. Crash

S2D

08-29-2002, 07:34 PM

Actually, the AD is just for the detents. If you can feel them you are ok. Doesn't mention how hard the thing is to turn. Although there is a limit to the whole thing. If it is hard to turn, it is hard to feel the detents. Had one cub that everytime it got hard to turn, I would run a load of cargas thru it and it would work good again for about 50 hrs then do it again. The New Univair valve is well worth the money.I've flown mine in -20 weather and pulled A/C out after much colder temps and have never had a problem with it. I've had it about 10 years now.

SuperCub MD

08-29-2002, 08:07 PM

cubdriver brings up a interesting point. There is nothing in the AD that really says anything about type of valve or P/N, I keep signing off the 100 hr AD even on the Univair valves, just to be safe. Does anyone know anything different? It would be nice to find some legal documentation to get rid of the AD.

T.J.

08-29-2002, 09:09 PM

delete

SuperCub MD

08-30-2002, 08:00 AM

That's what I thought, and I'll keep signing them off. I'll try to remember to talk to the good folks at Univair about getting the AD revised with a exeption for their valve, or at least a legal AMOC, if they can do it for the struts, maybe they can do it for the valve too.

cubdriver

08-31-2002, 02:17 AM

I swear I saw one advertised somewhere that eliminated the A.D.

supercub

10-15-2002, 10:15 PM

Just read all the post on the Univair selector, and since my stock one is getting very difficult to move, I'm thinking of installing one of Univairs. Any additiional comments, especailly on the installation ? Also, does it have a both postition, and can you legally have a both position without some kind of approval? Thanks
Brian

T.J.

10-16-2002, 12:33 AM

delete

Dave Calkins

10-16-2002, 11:09 AM

Brian, I totally agree with TJ on this.

I've been keeping the stock Piper valves alive until a/c rebuild by performing the AD.

If you do the Fuel Lube thing, it's likely that you may never perform a more satisfying and successful maintenance act until the next year's selector lube.

You won't believe how the lube makes the valve feel new again.

To get the proper detent action sometimes takes installation of a new detent washer thingy, if your original is worn.

I usually leave all the fuel in the tanks and just stick the proper size finger in the hole while my customer or whoever is around lubes the valve and puts on a new detent washer, o-ring, etc.. Yep, a little fuel leaks out when I fumble, but a bunch of time is saved.

Dave Calkins.

supercub

10-16-2002, 06:48 PM

Ok, thanks, I think I'm going to do that. The AI today showed me a selector we have in stock. It's a piper selector, has a piper part number and says it's for the PA-18, but has nylon or something similar to that inside. The AI said it was the selector used on the later model PA-18's and works smoother, I did turn it and it is very smooth working. Anyone know about this selector. Agin, it has a Piper p/n and on the tag says for PA-18 and some other models I don't remember which. I can get the p/n if needed. Just wondering if anyone has had any luck with this.
Brian
PS: I've asked this before , but I'm going to ask again. What is everyone using for Lube in the fuel selectors, best I can tell is Parker Fuel Lube is this the right/best stuff?

pak

10-16-2002, 07:05 PM

David, same is true with lubing the primer plunger. It is nice when both are silky smooth.pak

T.J.

10-16-2002, 09:07 PM

delete

Dave Calkins

10-16-2002, 11:39 PM

Yeah, Pak, I do the primers too, and guys will sometimes think it came out of the annual broken, because it pumps too easy and smooth.

The Fuel Lube fits a Mil-Spec.

Piper calls out this Mil-Spec. in the Service Bulletin for the valve.

There's a new product out called "Easy Turn". It also fits the Mil-Spec. I got it at Aviall. They were at one time handing out little tins of it that would last about a "half-life". This stuff is a bit smoother (not grainy like some fuel lube is) and didn't seem to get so stiff at cooler temps.

Fuel Lube and Easy Turn are both good for spreading thinly into threads on pipe fittings as well as spreading thinly on paper gaskets. Never use these products to "lube" cork gaskets or the cork will squish out from the mating surfaces and you may get a leak. O-rings are just fine with these products.

Just a heads-up.

Dave Calkins.

FlipFlop

10-17-2002, 07:39 AM

David C...

I use Fuel Lube for lubing and Seal Lube for sealing... Never thought that they may be the same thing... Hmmmm...

I sealed up an "experimental" oil leak ("experimental" oil temp sender threads) on the experimental Cuby with the Seal Lube a couple of weeks ago... Works good, lasts a long time...

Cub junkie

10-17-2002, 10:25 AM

el Saltamonte Piloto, I would like to see a couple pictures of your grasshopper, would it be possible for you to post some on the pictures page? A few details like engine and empty wt. am I asking to much?

FlipFlop

10-17-2002, 10:54 AM

CJ...

I'll try to find time to e-mail a couple of pictures to you... This weekend I installed a 10" Scott with Pawnee springs, so I didn't have time to work on my experimental long step...

I decided being a Catholic monk wasn't for me, so tomorrow I'm off to Texas to start my 3 week training course to be a WalMart greeter... I understand that the course instructors have worked together before... Their names are Bill and Monica, maybe you've heard of them... I'm hoping that by being away from my Mexican wife's cooking for 3 weeks, I'll lose some of my obesity...

Did I miss anything?... :lol:

Dave Calkins

10-17-2002, 11:47 AM

OK, I laughed out loud. I've had my eye on the Walmart rant also.

I'd love to see some photos of your Grasshopper, David.

Hey, another great product for lubing o-rings is Parker O-Lube.

It's super slippery and kindof stringy. Really hard to describe 'cause there's nothing like it. Good for lubrication when building flexible lines out of 111.

Dave Calkins.

S2D

10-23-2002, 08:19 PM

Just a couple notes on what I've seen on this postconcerning the AD on the valve.. The AD does mention a specific P/N of valve. It says in affected aircraft, all aircraft with 2 tanks and goes on to state the selector valve P/N 11383. It only has to do with the detent action, because of misaligned pin, although if you valve was so sticky you couldn't feel it this should apply too. Thus you can surmise that only the brass valve is applicable. Although the plastic one works the same way. and could have the same problem. Thus replacing it with the univair type that is completely different would eliminate the AD. If you are still questionable about it you can get the FAA to approve an alternate means of compliance with the AD. I realize since this check is only a function check and takes no time, it be more of a problem to get the FAA approval than to just check it. However it is really nice to see on the AD list-- No Longer Applicable-- kinda like when you put new struts & forks on. Just another sidenote. the AD says if you cannot feel the detents, the valve must BE REPLACED before further flight, not repair it. Wonder how many of you purists out there have written in the logbook that you repaired the valve in accordance with AD 60-10-08.
technically you nedd FAA approval to repair it to comply with the AD.