The International Cessna 170 Association

All:

I have a 1950 170A N9911A that is in need of a fuel selector valve.

My mechanic said that the Service Bulletin for this part has a $5,717 pricetag.

Any suggestions as to how I can get rid of the drips (minimal) and get this valve replaced at the same time without a multi-thousand dollar drain?

Thanks in advance for any advice / suggestions.

Sincerely,

Brett Preston N9911A

Talk to Sandhill Aviation in Hampton NH. They rebuilt mine at very little cost. They did show me the price from Cessna and I opted to have mine rebuilt.

It depends on which fuel valve you have. Do you have a brass Weatherhead valve such as that on the left? or a machined aluminum one such as that on the right?

What George is getting at is the one on the right found in 170B models can be rebuilt by replacing 0-rings.

The one on the left found in 170A and a few of the first 170B aircraft relies on a close tolerance fit of a brass cone inside the valve body. There are no o-rings or seals other than at the top where the valve stem sticks out.

If the brass valve has gotten a grove in it you may never get it to seal again. But in most cases removing, disassembling, cleaning and re-lapping the tapered cone to it's seat using a very light lapping compound will get it to work well and seal.

I would start off with some light car paint compound and go to heavy compound then valve lapping compound if necessary then reverse to the light stuff again. It will take some time but isn't hard to do.

You will probably be more successful if your mechanic has gray hair and has been dong this sort of thing for the last 50 years and if he's lived on a farm and maintained farm equipment so much better.

If you have the machined aluminum selector valve such as the one depicted on the right, the complete rebuild O-ring kit can be purchased for about $35 at:
http://www.mcfarlane-aviation.com/Produ ... r=FSS-KT-2&

Another message thread which discusses rebuilding the fuel selector valve extensively is:
http://www.cessna170.org/forums/viewtop ... 993#p10993

Read thru it ENTIRELY and carefully to glean all the important info, as several mistakes made by some of us have been discussed there...but the thread is very informative.

And....

if it is the aluminim (I never could spell) ... the one on the right, and if it's only leaking a little..

Clean the area under the valve, and the valve itself as much as you can from the inspection panels close to the valve on the belly. Place a small piece of notebook paper under each of the fittings; left wing tank, right wing tank and gascolator. Check the pieces of paper the next day. You may be able to isolate the leak to one of the lines. If it is one of the lines, you can try replacing the "O" ring on that one fitting.

If the paper shows no leak, turn off the fuel valve. Put a bucket under the valve on the floor and remove the pipe plug/fuel drain valve, thereby draining the fuel valve. Buy a new plug/drain valve (this step should have come just after paragraph 2), coat it with fuel lube thread sealant and re-install it. Don't over torque it!!!! turn the valve back on and check the next day to see if your leak has stopped. (This worked for me..little leak on the hangar floor..)

No-Joy, the leak is from the top of the valve and needs rebuilding. Buy the kit, hire a mechanic with small strong hands who can twist himself like a pretzel, work by feel, and get him to rebuild it for you. There's a reason he wanted to be an aircraft mechanic when he grew up anyway.

Good Luck

Shade-tree-John

N2786C '53 B Beat-up-patched up ole Alaska Bush Plane

P.S. Where is the spell checker on this website anyway? And how do I post one of those neat little pix of my baby?

johnsunday wrote:...P.S. Where is the spell checker on this website anyway? And how do I post one of those neat little pix of my baby?

Ol' Gar is our spel-cker... (we have a tight budget)....(and a tight spel-cker)...

...and to post a pic....be a TIC170A member and while posting, scroll down half-a-page to the "upload attachment" tab just below the message area.

I have two mechanics that have that so called "gray hair" and have just removed the valve (it is the old brass style).

It has a substantial amount of sludge on the base that seemed to press it up some. I have not looked at it through a magnifying glass yet to see if it is scored or worn, but I will run it over to the guys I trust and let them have a look at it.

Thank you for the advice and sorry for the delay in the return email.

Sincerely,

Brett Preston
N9911A

N9149A wrote:What George is getting at is the one on the right found in 170B models can be rebuilt by replacing 0-rings.

The one on the left found in 170A and a few of the first 170B aircraft relies on a close tolerance fit of a brass cone inside the valve body. There are no o-rings or seals other than at the top where the valve stem sticks out.

If the brass valve has gotten a grove in it you may never get it to seal again. But in most cases removing, disassembling, cleaning and re-lapping the tapered cone to it's seat using a very light lapping compound will get it to work well and seal.

I would start off with some light car paint compound and go to heavy compound then valve lapping compound if necessary then reverse to the light stuff again. It will take some time but isn't hard to do.

You will probably be more successful if your mechanic has gray hair and has been dong this sort of thing for the last 50 years and if he's lived on a farm and maintained farm equipment so much better.

Well, I must be a glutton for punishment, because I did it myself and now I know why I DO NOT WANT TO BE A MECHANIC.

Being into it up to my virtual elbows now, I have no choice but to press ahead.

I'll let you guys know how it all turns out.

N9911A is a real pretty plane and she should be flying again soon.

Ciao,

Brett Preston
9911A

johnsunday wrote:And....

if it is the aluminim (I never could spell) ... the one on the right, and if it's only leaking a little..

Clean the area under the valve, and the valve itself as much as you can from the inspection panels close to the valve on the belly. Place a small piece of notebook paper under each of the fittings; left wing tank, right wing tank and gascolator. Check the pieces of paper the next day. You may be able to isolate the leak to one of the lines. If it is one of the lines, you can try replacing the "O" ring on that one fitting.

If the paper shows no leak, turn off the fuel valve. Put a bucket under the valve on the floor and remove the pipe plug/fuel drain valve, thereby draining the fuel valve. Buy a new plug/drain valve (this step should have come just after paragraph 2), coat it with fuel lube thread sealant and re-install it. Don't over torque it!!!! turn the valve back on and check the next day to see if your leak has stopped. (This worked for me..little leak on the hangar floor..)

No-Joy, the leak is from the top of the valve and needs rebuilding. Buy the kit, hire a mechanic with small strong hands who can twist himself like a pretzel, work by feel, and get him to rebuild it for you. There's a reason he wanted to be an aircraft mechanic when he grew up anyway.

Good Luck

Shade-tree-John

N2786C '53 B Beat-up-patched up ole Alaska Bush Plane

P.S. Where is the spell checker on this website anyway? And how do I post one of those neat little pix of my baby?

Take your time it's really not that bad. Your arms will only hurt a little while after trying to force them further into the inspection holes than they will fit.

Your reward will be that good feeling of accomplishment when your done.......and it works.

New challenge.

I need a valve stem seal for the fuel selector valve.

The brass cone had a sludge build-up of between 1/8" and 3/16" which, obviously, forced the cone out of its' seat and contributed to the leaking. Now that it is all cleaned up (Never Dull Wipes, worked wonders), I need to put it back together, but the valve stem seal broke. It was as hard as a rock anyhow.

I can send dimensions and picturs it it would help.

Thank you again.

Brett Preston
N9911A

Brett I've not actually seen one of those seals. Is the packing a O-ring? Could an O-ring work? Could something at the local Ace Hardware look the same? Ask the local gray hairs.

According to CessnaParts.com packing 0413020-4 is know part number 38481. No other info like price or availability. You could call them. Parts Dept.#: 404-505-2074 Toll Free#: 1-800-998-7832

Having pulled my fuel valve out for an "o" ring replacement 10-12 yrs ago and again this year to replace all gaskets & "O" rings, I found getting the 3 steel balls in at the same time as putting the shaft back in to be a challenge, but the toughest part of the entire process was removing & replacing the two #10 bolts & nuts that secure the fuel valve to the bulkhead. Access is almost, but not totally, impossible to "get at". A poorly engineered set up in my opinion A couple of holes in the metal that covers the top of the valve area or placing the inspection opening on the belly a bit aft would have made that portion of the project MUCH easier ---- IMHO. Seems like someone, can't remember for sure, but think it was my IA said using some bearing grease would help hold the balls in place until the valve shaft is in place, then 100LL will clean out the grease before reinstalling the valve.

Frank you have a totally different fuel valve than Brett. He has the old version, you have the newer one. Nothing is the same between them except for their function and location.

My seal was a felt style collar. Approx 1/2" high that fit the shaft.

John