The Cessna 120-140 Association Forum

Hello,

My fuel selector is the brass to brass type, with L-B-R-Off positions.

It has been cleaned and serviced twice in the 22 years I have the airplane, last service in 2012.

It has today a very little leak when in Off position, If I drain from the gascolator it drops gas very slowly instead of cutting off completely.

I dismantled it today and found the parts as shown in my ( very poor ) drawing below.
From bottom to upper parts, I found:

1 A spring that does not seems to be original (compared to the drawing in document " fuel selector aug 05.pdf " that is available in this forum,

2. A brass washer, flat on the bottom side and slightly inwards curved on the top surface,

3. The conical brass spool

4. A rubber spacer, of cylindrical shape,

5. O Ring

Finally, two questions:

Q1
Is this assembling order correct ? May I get a detailed view for assembling it correctly ?
The PDF file does not show a drawing.

Q2
What grease can we use to mount the brass to brass valve ?

I use UL91 Avgas with no alcohol / no lead.

Thanks very much,
Horacio

Horacio,
Here is a pic of the standard 3-way valve from my bird, it is a Left-Right-Off version so it does not have the 'both' option. I do not have any experience with the 4-way valve.

Nevertheless it shows the basics of assembly. I do not recall ever seeing a spring on the bottom of the truncated cone, it seems counter-intuitive.

The wavy washer does not look familiar at all.

Most people use a very small amount of EZ Turn lubricant. Some folks have had success in lapping the two contacting surfaces (out of the aircraft and well cleaned up afterwards).

There is discussion about automotive gasoline causing the rotating parts to get sticky.

Hope this helps a little.

If you have been leaking fuel, take a good look at all your wiring through all available inspection ports. Mine originally went in for a fuel selector service when I first purchased.... without knowing fuel had eaten into the wiring and I had bare hot wires exposed with fuel leaking on them... aside from the risk of fire, my mechanic got the crap shocked out him.

Thank you Dave and James for your quick answers,

It does help a lot !

Fortunately I had not leaks in the valve itself that could have damaged other components inside the airplane.
What I noticed is only that the cutoff position allowed a small gas flow if I drain the gascolator, instead of completely closing.
So from that side I am safe.

EZ turn lube is not available here, I have read its tech specs in Aircraft Spruce after getting your post.
I will try to get something similar, but if I dont get it, I will mount the valve with no lube, and wait two or three weeks to get it from A. Spruce.
Anyway, to lubricate the valve is easy, it can be done without removing the valve body, just dismantling the moving parts from the top.

Thanks again and have a nice Sunday !

Horacio

The spring should be above the plug, pushing it down into the tapered valve body. With yours pushing up, I'm surprised it shuts off at all. Also, if your valve is original, it sounds like you're missing the detent washer that makes it "click" into the various positions. This goes between the spring and the top of the plug and does not appear to be in the photo, either.

Item 2 sounds like it may be the washer that separates the spring form the original leather seal and pushes it up into the cover. Its upper surface would be concave to match the shape of the underside of the cap.

Hello Horacio:

I agree with John C. Possibly you do not have the original OEM valve, however, if yours has been working to your satisfaction, except, for the current issue, I think I would just clean up and lube with the EZ Turn, which will probably seal off the minor seepage.
As to the detent washer that John C mentions, years ago I was doing an annual on a friends Beech Musketeer and someone had worked on the fuel valve resulting in a broken detent washer among other things. A new valve from Beech was IIRC over $1K but fortunately they had one and only one detent washer left on the shelf!
Another similar product as EZ Turn is called Fuel Lube - both are excellent on all fuel line fittings also.
That being said, a can is generally a life time supply. If you will send me your mailing address, I will put a small quantity in a plastic bag and flatten it out so that it should pass as a normal letter - I'll enclose a copy of the Spruce ad in the event the Postal people should question the material.
Just taking a "lesson" from John C - I've noted him doing similar responses to others in need.

Big Edd
moxcart1@wmconnect.com

Horacio,
Here is a picture of another Imperial/Weatherhead valve that shows a little different arrangement, especially the detent washer and the groove it fits into on the body of the valve. Mine did not have the detent washer or groove so it didn't 'click' into position, go figure. Since remedied with another valve.

The old style packing (the rubber washer item) is hard to find, but I have a mention of a fuel injector o-ring kit that had two fat o-rings that work as a stem packing. It's Napa # 2-12085, about $4.50. Also, I have a reference for MS29513-011 0-rings, either 1 or 2 as an alternative to the old packing.

"The old style packing (the rubber washer item) is hard to find, but I have a mention of a fuel injector o-ring kit that had two fat o-rings that work as a stem packing. It's Napa # 2-12085, about $4.50. Also, I have a reference for MS29513-011 0-rings, either 1 or 2 as an alternative to the old packing."

I would like to confirm that the Napa part number 2-12085 fat o-rings are a legitimate repair for the Imperial/Weatherhead valve pictured above (Mine is a 4-way valve). I just finished replacing the original cork packing with the 2 o-rings in the Napa fuel injector o-ring kit. Below is a photo of the fat o-rings along side the MS29513-011 0-ring. I do not see how a stack of the MS o-rings would have been an effective repair, the OD is way to small to fill the opening in the "cap" of the valve that was filled with the original cork packing. The ID does fit the shaft.
The ID and OD of the NAPA o-rings were a perfect fit on the shaft and in the cap. Nice and tight. The valve now has a good snug feeling and a very definite click at each position. I was able to do the repair with the valve still in the plane. Tough, but doable. I have really small hands and lots of patience!

My IA agreed it was a good fix for the valve.

Price of the NAPA kit was $4.19 plus tax.

Hope this helps.

Steve A H

8424 wrote: ↑Tue Aug 17, 2021 6:46 pm Below is a photo of the fat o-rings along side the MS29513-011 0-ring. I do not see how a stack of the MS o-rings would have been an effective repair, the OD is way to small to fill the opening in the "cap" of the valve that was filled with the original cork packing. The ID does fit the shaft.

You need an MS28513-109 MS29513-109. (5/16" I.D. x 1/2" O.D.) I used just one, and a brass spacer to make up the difference.

Hi John!

Thanks for the MS number. Would you confirm it is a 28513 and not 29513?

I knew there had to be an MS o-ring that would work, but didn't want to start tearing open the packets to try to figure out which one to use. The IA would have been a little upset at me for messing with his stock! I should have used Goodyear's catalog to figure out which one to use:

https://www.goodyearrubberproducts.com/ ... og2010.pdf

I'm going to leave the injector o-rings in there and will use the MS if they start leaking. It would be nice if I'm long gone when they do! I'll find out how they hold up to avgas. If there's a problem I'll report it in this thread.

Steve A H