Fuel selector valve

[U2Hoog]

I'm looking to replace my fuel selector as the old one has seen better days. The detents are gone. Any suggestions on new ones which fit the bill for a C-170 (1948)?

[zero.one.victor]

I've never had a Cessna fuel valve apart--is the old one not rebuildable due to the detents being gone? Or are the detents a replacable component? I've seen some detents on other mechanisms that are a ball-bearing/spring arrangement.

Eric

[U2Hoog]

Okay, here's the real scoop. I was flying the other day, parked the airplane, and came back after a week. (I was on an airline trip). Upon return, I found the left wing completely empty, my hangar floor blue, and at least 10 gallons of 100LL gone. (no this wasn't theft). The A&P came over to the hangar and we traced lines and couldn't find a leak anywhere. We're still troubleshooting, but everything seems to point to the fuel selector or perhaps a flange being cracked on the line(s) going into the selector. He's rebuilt the selector once for me about 2 years ago, but if you didn't know where to stop the selector, you wouldn't know you were in left, right, both or off. No detents that I can feel at all anymore.

SO... he recommended we change out the old fuel selector while we're troubleshooting. Which brings me to my original question. And there's the complete story.

Thoughts?

[jon s blocker]

Is the belly of the plane blue? Could it have been the wing tank drain/ check valve, or possibly your gascolator? take your valve apart and put some new detent indentations in the track by drilling very shallow indents where the old ones were.

[U2Hoog]

Good inputs. I'm off to the hangar. We'll let you know what we find!

[blueldr]

That fuel selector valve has a ball bearing ball riding on the detents and I have never seen a sign of wear on that part. The small ball unseats a larger ball to open the line from the tank so there is almost no friction on anything. The only problems I've ever seen were worn and leaking shaft seals. The selector valve can be a real bastard to remove and install.

[Curtis Brown]

I almost always keep my fuel selector in the both position. I assume because of this it has become very stiff and difficult to turn. The other day I was disconnecting the fuel line from the gasculator and after placing the selector in the off position I was still getting some leakage. Does this sound like I will need a new selector?
Curtis

[U2Hoog]

John Blocker,

Well, having searched the belly, I can tell you for certain it is NOT a leak between the selector and gascolator. No blue stains there at all. I put 10 gallons in 2 days ago and I'm already seeing signs of fuel "disappearing".

No blue stains on wing, or side of the aircraft. The only stains are in the vicinity of the fuel selector (you know how hard it is to see up in there (or down there even with the carpets pulled). In any event, it looks like we're going to pull that thing and either replace it outright or rebuild.

Anyone have suggestions / comments on the replace vs rebuild option?

"Hoog"

[jon s blocker]

Hoog,
I just rebuilt my selector valve about a month ago. It is very simple to rebuild. If I recall it has 5 or 6 o-rings to replace and depending on the shape it is in there is a thin gasket that you may have to replace, (this you can make yourself). There is a very small o-ring that you replace, that you have to remove a roll pin, don't forget to replace that one, it's the hardest one to replace, but a very good place for a leak! While you have the top piece off, you can check the detent problem. It may very well be the spring and ball just have some rust or crud caked in the housing and a little penetrating oil will free it so that you can dissassemble them to clean them up. don't forget to grease it, and unless the valve is corroded, it should be good as new. Someone had posted an article on the part numbers and pointed out that there was a mistake in the sequencing of one of the o-rings in the parts catalogue, but I don't recall who did this. It was a good article and done on this post I believe. The rebuild costs about $5. I will see if I can find a copy of the previous article.
Jon

[N1478D]

And that article, or another, mentioned using special grease made to be in an application with fuel.

[U2Hoog]

Jon & Joe, thanks. Hopefully that'll fix the problem. The A & P thinks I may also have a cracked flange on the left fuel line going into the selector. Just speculation on possibilities at this point.

More to follow.

"Hoog"

[Bruce Fenstermacher]

I posted the article previously mentioned. It can be found if you search under "Fuel valve rebuild and manual mistake WARNING"

[Curtis Brown]

Well, as I suspected, I need to replace the fuel selector valve. It does not leak fuel out of the airplane, it just does not seal off fuel to the gascalator. The cost is about $500 at best and I was hoping someone might know a better solution. The A&P says I need to replace it . The part number is 0413020-3 superseded to 9851085-1. I have read the previous post about rebuilding the valve but that does not appear the problem with this valve. It must not be sealing off due to the brass fittings inside.
Can anyone offer a solution?

[GAHorn]

Curtis, if you've not tried rebuilding your valve, you should do that first. The only thing that wears out on these things is usually some cheap o-rings.

[superpilot_75965]

I had this same problem a year ago. I disassembled the valve. My valve showed excessive pitting and was too far gone to hone out the pits. I had to buy a new one. the replacement part isn't an exact replacement.