The International Cessna^® 170 Association

Looking for information/ helpful hints on rebuilding 1948 fuel selector. Serial number 18065. Slight leak coming from one fitting, and it drags really bad when you try to switch tanks. Looking for info on how to get it out, and what is needed to rebuild it. Thanks.

Take a look at the Cessna 120/ 140 association website. They have a lot of great info on rebuilding and maintaining the older fuel valves.

Here's a good place to start

http://www.cessna120-140.org/forum/file ... ug__05.pdf

First of all...STOP trying to move the valve if it is getting rough or troublesome, or you may damage it beyond repair.
It is composed of a conical rotating plug inside a brass/bronze body and will "score" and be damaged if it is forced.

Drain your airplane fuel system and remove the valve. (You will have to disconnect the operating universal-drive-shaft from the "cone". Remove the "cone" from the body by unscrewing the large nut which surrounds the shaft, and then pulling the cone out of the body.
Clean up the valve parts, and if necessary, use fine valve-lapping compound to re-seat the cone. Clean thoroughly and lubricate with EZ Lube or Parker Fuel Lube (fuel proof greases) and reassemble.

If you are careful you can save/re-use the "packing gland" or you can use an appropriately sized O-ring (Viton or nitrile) to reseal it.

Reinstall it.

NOw, beware: The 48 model used two differing locations for that valve. The one early serial (before 18574) placed it beneath the cockpit/flap-tunnel, while the later serials had it beneath the instrument panel. If you're lucky, you have a late serial.
If you have the early serial, removing the valve is not too difficult, but reinstalling it will result in scratches, bruises, and a new vocabulary. (See last years's "The 170 News" article I wrote about this project for further information, but you'll figure it out...just be patient.)

Hope this helps.

I recently saw a 48 140 with one of the brass valves that was scored beyond repair. It got replaced with a new fuel valve from Graingers (if I remember the correct source). Not kosher with the FAA, but it was identical except for not being legal.

gahorn wrote:First of all...STOP trying to move the valve if it is getting rough or troublesome, or you may damage it beyond repair.
It is composed of a conical rotating plug inside a brass/bronze body and will "score" and be damaged if it is forced.

Not to worry. We were told the same thing, so we have stopped spinning it.

No such luck on the serial number. We have serial number 18065, so it is tucked down in the annals of hell!

Are there any legal replacements for this, if it is unfixable?

Thanks for the help guys! I will check out the article.

Ken,

If you could find a valve at Grainger or any other source that was exactly the same as the original, you can use it under the guideance of AC 23-27 Parts/Materials Substitution for Vintage Aircraft. Good luck. Hope you would find one exactly like it. You might also be able to get approval for a nearly identical part using AC 23-27 as a start. Most of the available fuel valves I've seen from time to time are identical except for one thing. They don't have a both position. This could be added but the valve as it is is not identical.

There might be some hope through Univair. They have been working on a replacement fuel valve for the Cessna 140. I believe we learned they had gotten the approval for it but not sure if they received a PMA or an STC. I also don't know the price.

The Cessna 140 valve is the same valve by part number that is used in the '48 170. If Univair received a PMA to make the valve for the 140 then that same valve would be legal in a 170 because essentially they are making a replacement part for the original. If they got an STC then the part would only be legal if the STC covered the Cessna 170. If made Jim Dyer, President of Univair aware they are the same valve and Univair should make sure the 170 is included in any approval process such as an STC.

If in fact Univair got an STC for the 140 but not the 170, you might use the STC and part with seperate approval based on the fact they were the same part.

NOw, beware: The 48 model used two differing locations for that valve. The one early serial (before 18574) placed it beneath the cockpit/flap-tunnel, while the later serials had it beneath the instrument panel. If you're lucky, you have a late serial.
If you have the early serial, removing the valve is not too difficult, but reinstalling it will result in scratches, bruises, and a new vocabulary. (See last years's "The 170 News" article I wrote about this project for further information, but you'll figure it out...just be patient.)

Hope this helps.[/quote]

I did it two years ago using that method. I also recommend using plenty of fuel lube upon reinstallation. Your so right, I have the early one, mine is serial number 18527. What a tight fit, having a set of crows foot wrenches really helps..... and I too expanded my vocabulary....

The PMA'd valve sold by spruce for a 140 does NOT have a Both position.

Got the valve out of the aircraft, and taken apart. Bronze sealing surface looks really good. Not worn or galled much at all. Dabbed on the fuel resistant grease, and works like a charm. However, when putting it back together the bronze "cup" (I guess you would call it that) that pushes down on the detent rocker washer, broke while putting it together. Anyone else have this happen? Know of a replacement? Have one machined from a piece of brass? Thanks.

Ken, if it were me, besides cleaning and greasing, I'd lightly lap in the cone. then clean and grease, reassemble and test before install. As for the broken part unless your lucky and someone has one to send to you, I'd have one made (actually make it myself).

gahorn wrote:The PMA'd valve sold by spruce for a 140 does NOT have a Both position.

Since they have a PMA for the original part for the 140 it should also be the same part for the 170. (I'll bet it actually is a Univair part)

My example of off the shelf valves with no both position was only an example of the difference I've seen between them and OEM fuel valves. I idn't mean to imply the Cessna 140 or 170 should have a both position.

Not a bad idea on the lapping. I will have to are what our IA thinks. Causevit wasn't leaking before. The packing on top still looked good as well. Not terribly hardened. So hopefully it seals good. Am I right that it is no longer available? Replaced with orings now if it leaks?

I assumed it leaked before which is why I suggest the light lap. If not then I wouldn't lap. But I sure as heck would test it to make sure it still wasn't leaking before I installed it.

No, it wasn't leaking. Maybe a slight seep if anything. Just needed greasing badly.

Got the valve assembled, and tested by capping two ports and attaching 6 foot line to other port. Filled line to fuel to get a head pressure, and let it sit. Turning it to each tank and letting sit there as well. No leaks that I could see. Got it back in aircraft, and everything buttoned up. Thanks for the help everyone, it was invaluable.