|
|
 |
|
|
|
| Author |
Messages |
Bob Brock
Unregistered
|
      
 Posted Wednesday, May 2, 2012 @ 05:03 PM
Greetings:
One of the good things about removing the engine again is that we discovered a small fuel leak on the shaft of the fuel shut-off valve. It appears to drop a very minor amount of fuel when the valve is opened but not when it is shut-off. With the valve off the aircraft, we filled the valve with fuel in the vertical position and confirmed a drop from the shaft. But removing the pin is difficult and before I caused any damage, I wonder if a forum member can tell me how the valve comes apart... for example, is the pin tapered or straight? And is an "O" ring used on the shaft to keep fuel in the valve?
Here is a link to several pictures I just took showing the shaft in question and the pin (just driven flush). Or is there another fix that I missed? Everything else is tight and does not leak. I used new hoses and washers.
https://picasaweb.google.com/lh/sredir?uname=Bomar1&target=ALBUM&id=5738039610197605889&authkey=Gv1sRgCKWW6an4jqDGoQE&feat=email
Any ideas would be welcome. Thanks... Bob Brock
|
Jorgen
Unregistered
|
Posted Wednesday, May 2, 2012 @ 05:56 PM
Hi Bob,
I haven't dismantled this Fournier gas valve, but have you tried to undo the nut/lid between the pin you marked and the valve housing? Once apart (my bet is that it's tapered, that's how the Cub valve is that I recently changed) there is a magical goo called "EZ-turn" (fuel resistant fat) that you can use to make it less leaky.
May the 4's be with you/ Jörgen
|
Markku
Unregistered
|
Posted Friday, May 4, 2012 @ 04:59 AM
Hi
I have the same problem with the fuel valve. Attached few pictures of dismantled valve cam shaft. The sealing is hard, square shaped, and broken, might have been once an O-ring. Does anybody have replaced it before.
How to seal the thread between the valve and the cam shaft sealing box, originally it is done by some clear and very hard sealing compound?
|
Bob Brock
Unregistered
|
Posted Monday, May 7, 2012 @ 11:50 AM
Markku:
Thanks for the images... a picture is worth a thousand words.
We all know how rare RF-4's are in the US.... but imagine that I could get two additional fuel valves immediately. Both Collin and Dann Parks offered to loan me their RF-4 fuel valves. Since Dann is using a completely new fuel valve, I borrowed his original valve. Yesterday I went to Dann's and picked it up (nicest day of the year so far). When I was in his shop, he verified he had oil pressure in his new engine (not wanting to follow in my footsteps). Needless to say, having Collin and Dann nearby makes the rebuild easier. I can not wait to see our aircraft side by side... I followed Eugenios many suggestions regarding fiberglass and painting, etc. and Dann used PolyFiber. Also, I think Dann invested lots more money into his rebuild. It will be interesting to see how it all works. Both aircraft should be flying in a month or so. Here is a link to a few pictures I took yesterday.
https://picasaweb.google.com/lh/sredir?uname=Bomar1&target=ALBUM&id=5739811703425768241&authkey=Gv1sRgCIPx6IrzmJ2IsAE&feat=email
|
Jorgen
Unregistered
|
Posted Monday, May 7, 2012 @ 04:06 PM
Thanks for the pictures and updates, please let us know the diagnosis of the leak. Since the valve is not tapered my next bet is a weak spring and worne-out O-ring as culprits.
Hope you Guys get in the air soon, I had a very nice 2-hour flight today with engine time 20 minutes and glider landing. Just so you know what's waiting...
May the 4's be with you/ Jörgen
|
Markku
Unregistered
|
Posted Tuesday, May 8, 2012 @ 08:49 AM
Bob
You mentioned in your Picasa link, that Dan's valve was filled with gunk, then it's most obvious , that the sealing box is also filled with that same stuff. It might be impossible to clean it without dismantling first
Markku
|
Jorgen
Unregistered
|
Posted Wednesday, August 5, 2020 @ 06:24 PM
Hello Fournieteers,
just to try to help collect "How to do it"-guides on here... The fuelvalve on the RF 4 is of "Le Bozec" brand and is used in Jodels too. I had a fuel leak from the fuelvalve (dripping from the wheel of the valve) so took it out which isn't as bad as it looks. The snail is 8-10 wooden screws and on "XST" also the starter handle. From the wheelwell you can unscrew the fuel hose and the nut on the front of the valve. The lever I found was easiest to remove by unscrewing the tab for both the choke and fuelshutoff handles in the cockpit so you get the whole arm out with the valve so you can fiddle with the cotterpin etc outside the aeroplane.
So this is the fuel valve when you start to dismantle. The slotted screw on the lever on the right was tough to get out and changing that to a recessed insec-screw would probably be smart. Be careful when you undo the nut on the axle, note the ball/spring onto the wheel that is easy to loose. The pin in the axle is tough but not impossible to get out, the wheel is a tight fit on the axle but needs to come off. Take note of the orientation on the axle when you remove the wheel.
This is how the axle and the cam looks when you disasemble it. On the axle there is a spring, a metal washer and (on XST) a square looking black washer that was cracked. We believe this is the culprit to the leak and we also think it used to be an o-ring. We replaced it with an O-ring and put the valve back together. The movment of the arm feels a lot smoother, I will get back to you if we still have a leak...
May the 4's be with you/ Jörgen
|
Bob Grimstead
Unregistered
|
Posted Thursday, August 6, 2020 @ 05:47 AM
Thank you Jorgen,
I have always wondered what those things looked like when dismantled.
I was told by a Jodel 'expert' that it is impossible to dismantle them without breaking them.
I am very glad to see you have proved that to be wrong.
They are fitted on the RF6Bs I am restoring too, so that's a little job for me when I get back to England
Happy Fournicating everybody.
--------------------
|
Jorgen
Unregistered
|
Posted Sunday, August 16, 2020 @ 02:28 AM
No worries mate (you're still stuck down under right Bob?),
and I'm happy to report no leaks so far- at least not from the valve. Eagerly awaiting the carb overhaul-kit from Eugenio...
The "Le Bozec" fuelvalve in place to the right on the firewall (the shaft to the fuelshut off lever sits too low in this pic because the tab fitting it too the panel is not in place). Just a comment on sealing the threads that we discussed before, the nut on the firewall is outside the seal which is a conical fitting so if there's a leak there it would appear it's a "lapping in"-job that needs to be done. The bolt on the fuelhose fitting from the tank at the rear is hollow so fuel actually flows through it, the rear seal is two washers, between the bolt and the fuelhose fitting and between the fuelhosefitting and the fuelvalve. If there's a leak there I would check the washers.
As far as I understand the O-ring we mentioned seals around the shaft on the fuelvalve so I didn't put any sealant on the threads of the nut on the shaft. If it takes another 50 years to wear the O-ring down so it leaks again I guess i'll have to take it apart again...
And incidently I think it's actually the fuelvalve itself that constitutes the limit of how far you can move the rudderpedals forward, as far as I could check the absolute max you can move is 8 cm, then you'll hit the valve.
May the 4's be with you/ Jörgen
|
Markku
Unregistered
|
Posted Wednesday, August 19, 2020 @ 04:07 AM
Hello Jörgen
The thread should be sealed also, because the whole valve is filled with gasoline, the O-ring is sealing only the valve cam shaft
|
Jorgen
Unregistered
|
Posted Friday, August 21, 2020 @ 02:40 AM
Good point Markku,
but I don't know. If you look at the nut on the camshaft there are what- three threads? On the other hand there could be room for an O-ring between those three threads and the flange on top of them. However, there where no traces of any O-ring at that location on XST.
I'll keep an eye on it and check for leaks, thanks.
May the 4's be with you/ Jörgen
|
Donald
Unregistered
|
Posted Friday, August 21, 2020 @ 02:46 AM
Hi Jorgen.
Thanks for the insight on the fuel shut-off valve. My RF3 also has this. Mostly it has been trouble free and so far I have not felt the need to dismantle, but you never know.
Anyway, I have a question. You write "On the axle there is a spring, a metal washer and … a square looking black washer that was cracked."
What do you mean by a square looking black washer? I cannot see anything in your photo that fits that description and nor can I imagine a square anything in a device which is largely cylindrical. Can you clarify please? Do you mean that the cross section of the black washer is square rather than the plan view of the washer is square?
I presume the actual shut-off is achieved by the cam shuttling a plunger along inside the casing.
[Edit by Donald on Friday, August 21, 2020 @ 08:31 AM]
|
Jorgen
Unregistered
|
Posted Friday, August 21, 2020 @ 06:26 PM
Hi Donald,
you are correct on both accounts, the cam pushes on a plunger that shuts the valve, you can almost see the plunger inside the housing on the pic with the disassembled valve. On that same pic you can also maybe spot the spring and a metal washer but the black "thing" that I for lack of better word call a "square looking washer" indeed had a square looking cross section and my impression is that it was once upon a time an O-ring which would then of course have had a round cross section when new. That it was cracked is to me evidence it was indeed old and worn.
Markku's suggestion that the threads needs sealing is not that evident to me. At the forward and aft ends there is a conical and washers to seal, I did not see any evidence of sealing compound beeing used on the threads and I've seen no leaks for the 20 years I've been the custodian of XST.
May the 4's be with you/ Jörgen
|
Donald
Unregistered
|
Posted Saturday, August 22, 2020 @ 01:46 AM
Hi Jorgen. It took me a few re-reads of your description and study of your photos to make my assumption about what you must mean by 'square' but thanks for the confirmation.
Having had some frustrating experience of leaky threaded connections on domestic fuel oil lines I can sort of understand Markku's concern about thread sealing the cam shaft bushing. However I agree that there appears to be no sign of old sealant on the threads of your valve.
Your caution about the ball/spring being easy to lose is very worthwhile. It would be very easy to carelessly have that ping out never to be seen again. 
|
Markku
Unregistered
|
Posted Tuesday, August 25, 2020 @ 01:53 PM
Hello All
The yellow marked thread should be sealed, Eugenio recommended some teflon stuff, I don't remember the type or manufacturer
|
Jorgen
Unregistered
|
Posted Saturday, September 12, 2020 @ 04:55 AM
Thanks Markku,
that's a really neat drawing. I'm still not done tinkering and need to remove the snail again to fix the throttle cable so I might put some locktite or similar on there.
May the 4 be with you/ Jörgen
|
bill.tugnett
Unregistered
|
Posted Tuesday, March 26, 2024 @ 02:09 AM
A suitable thread sealant for gasoline is Loctite 577. It is resistant to fuel, oil, hydraulic fluids and coolants. Regards, Bill
|
JamesH
Unregistered
|
Posted Monday, July 8, 2024 @ 01:28 PM
Currently replacing the o-rings on 4 of these valves.
Had this tool made to get the large round selector off which was stuck on severeal and needed something more subtle than a hammer
If anyone is stuck and needs to borrow it let me know
[Edit by JamesH on Monday, July 8, 2024 @ 01:29 PM]
|
|
|
|
|
|
|
|
|
|
|
| Login |
|
|
In order to fully utilize the abilities of this board, you are required to register as a member. Registration is free, and allows you to do lots of things including turning on or off certain features of this board. Register now! |
| Forum Rules & Description |
Who Can Read The Forum? Any registered user or guest
Who Can Post New Topics? Any administrator or moderator
Who Can Post Replies? Any administrator or moderator
Who Can Edit Posts? Any original author
|
Tips for maintaining Fournier Motor gliders |
| Currently Active Users: 243 |
There are currently 0 members and 243 guests on the boards. | Most users ever online was 42535 on 04-07-2026 02:43 AM
|
| Search This Forum |
|
|
|
|
Powered by CuteCast v2.0 BETA 2
Copyright © 2001-2003 ArtsCore Studios
|
|
