The International Cessna 170 Association

when i took mine out to clean/lap it, it already had an O-ring in it. I've replaced it a few times, I'll have to look to see what p/n it was and I'll post back.

v/r,
Jud

Go ask the gray hairs?

Hey, Gray hair is a state of mind and not necessarily indicative of a persons perception, willingness, or ability to do things that may or may not be politically correct.

Gray hair as I used it equals a person with common mechanical sense and old time experience. Doesn't mean they have to have gray hair but unless they've been apprenticed by one they are probably over the age of 40.

IM.,
Reduing one right, now, just drain your fuel out of the 170 ,or 172 ,there both the same parts,
, remove the fuel selector valve,from the aircraft ,take the screws out just be carefull of the
ball bearing and spring on the selector shaft,then when you remove the plate ,there are two
more ball bearings ,to watch for,in the main body ,then put your new rubber o ring in and
hook your spring and ball bearing back in to the selector arm which holds the o ring in place
after you put the pin back in then keep the two ball bearings forward in there holes ,after
your cork gasket is reinstalled ,put the shaft and top part back in keeping the ball bearings
in there holes carefully reinstall the shaft it only goes one way ,then when you push down
and the ball bearings stay in place ,relace screws,and you just have to ,put it back in the fuselage,
ive completed several of these, including the one in my Cessna 170B., GOOD LUCK $5,OOO.OO,
is making people wanting to stop flying , i have picture, but dont know how to send them ,i will
be 70 yrs in April ,so i guess i quify for the gray hair ok.,parts numbers are in the Cessna 170 and
172 parts Manual

Paul

1954 Cessna 170B OWNER
Member 6849

Paul your, right the B model valve is not difficult in most cases to rebuild. But the A model and B model valve to serial 20285 is completely different than the later B model. No balls, springs or o-rings inside it. Just a cone. And when the cone gets galled up to much, it will not seal and may be trash.

Bruce.,
ok you got me, i was talking about the 170B, Model that i own, and 1967 Cessna 172H that im doing today
any way i hope that the $5000.00 dont have to be looked at it makes it not fun to fly anymore ,have a great
day sir.

Paul.

Bruce Fenstermacher wrote:Gray hair as I used it equals a person with common mechanical sense and old time experience. Doesn't mean they have to have gray hair but unless they've been apprenticed by one they are probably over the age of 40.

I just got one of those new fangled email notifications to a topic on this here website. For the life of me, I could not remember posting on a topic such as this one, because I have no expertise in fuel leaks
But I have to say reading this topic reminded me why I love this website forum.

Bruce, I hope you did not take my previous post in 2008 to be offensive. It was an attempt at humor, but before I knew how to use them smilie face thingies . I would also add I think that particular comment may be the most valuable advice available to anyone..........

"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." Bruce-2008

And I had gray hair then too

Del, you got the notice because you subscribed to the topic. You will get a notice every time something is added to it. While viewing the last post scroll down to the bottom of the page and in the blue bar about an inch from the left with probably be the words unsubscribe. Clicking this will of course unsubscribe you from the thread and you will stop getting the notices.

I don't remember being offended. BTW I was describing my airplane partner, Leroy and the description fits so many others as well.

I am going through my '51 this winter and thought I'd add some pics. Coming apart wasn't horrible; going back together just might be. Can folks tell me if this is the quick drain kit that was typical? Also, you will notice some clever fellow in the ship's past had some brass glue to make the mounting bolts behave when going back on.
Did not have a leak but made the assumption that it would leak as soon as I filled tanks first time. Took a little heat to get things apart. Anyway, it looks beautiful to me! Bonus since I didn't find $5k in the belly! I will probably spend a few quality minutes with some toothpaste between the tapered pieces since it's apart.
I have seen reference to MS29513-011 as a replacement for the o-ring. Also, the cupped washer does not surround the spring. The four cutouts in the washer are what create the valve detents (along with the pin through the shaft) and the outside tab keeps it from spinning. There is a little wear on the bottom face of my detent washer so I'm flipping it over so it will be crisp for another 65 years.

Todd

That is imaginative use of hardware to replace the original AN913 drain plug.

That fuel valve would likely enjoy a dab of EZTurn or Fuel Lube during reassembly. Thanks for posting the pics.

I Hope that this fits in with the original intent of this thread. I am also having an issue with the fuel valve in my 1951 C-170A, SN 20155. I haven't crawled under the belly to see which valve is installed, but I assume that it is the original brass valve that came on it from Cessna. It turned extremely hard, and developed a leak, so it was removed for service at annual time. It turns nice and easy now, though I am unable to detect any "detent" at each position. I turn the selector to "both off" each time i park in the hangar. Also, I was looking the plane over the other day. While I was looking things over, I noticed that the gascolator bowl was only half full, and though my sense of smell isn't all that keen, it seemed as though I could detect a bit of 100LL smell in the cabin. I can only assume that this is coming from the selector valve, considering both of these things. I am curious as to how the stem of the valve is sealed? Sorry for such a long post!
Ty

prairiechicken wrote:I Hope that this fits in with the original intent of this thread. I am also having an issue with the fuel valve in my 1951 C-170A, SN 20155. I haven't crawled under the belly to see which valve is installed, but I assume that it is the original brass valve that came on it from Cessna. It turned extremely hard, and developed a leak, so it was removed for service at annual time. It turns nice and easy now, though I am unable to detect any "detent" at each position. I turn the selector to "both off" each time i park in the hangar. Also, I was looking the plane over the other day. While I was looking things over, I noticed that the gascolator bowl was only half full, and though my sense of smell isn't all that keen, it seemed as though I could detect a bit of 100LL smell in the cabin. I can only assume that this is coming from the selector valve, considering both of these things. I am curious as to how the stem of the valve is sealed? Sorry for such a long post!
Ty

The stem is sealed with an O-ring. I've seen three different assembly-methods. 1-a thick square-cross-section rubber seal, 2- a special-size flat-washer with an O-ring, 3- two O-rings with no flat washer. They all worked fine and apparently reflect design changes over the years from the original mfr'r Weatherhead. Aircraft Spruce sells an almost identical valve for experimentals with a slightly longer shaft and a more modern sealing system using a poly-mfr'd cone. It is the modern equivalent Weatherhead makes and although I'm not specifically recommending it, once installed I doubt it could be differentiated by an inspector who isn't a "gray hair".

PS: For those who have the later machined-aluminum/block fuel selector valve there is another option to sending $5K-Plus to Textron: McFarlane makes a direct replacement for approx. $1K. https://www.mcfarlaneaviation.com/produ ... or-valves/

Thank you, Mr. Horn for the reply!

I suspect IF you have a leak, it is the quick drain on your gascolator. But I wouldn't be surprised you find no leak at all.

When your selector is turned on to both or left or right you have head pressure from the both tanks or left or right tank depending on the selector valve position. In the Off position there is (shouldn't be) pressure past the valve however both tanks are tied together so fuel will level out between the tanks.

As there is no head pressure a seeping gascolator valve might seep a small amount, almost undetectable and only stop when suction is sufficient to hold remaining gas in the gascolator. You may have just been smelling the gas from around the gascolator.

I'd look at this first though looking at the valve won't hurt.

Do you turn the selector off with your engine still running. That could also account for a slightly empty gascolator as well as a dripping carb.

But don't be surprised if you find nothing wrong. From time to time I've come across half full gascolators when the fuel is off. Mostly in my Cub however.

Wanted to add to George's comment above about the use of AN parts to plum the sump valve on the selector valve. The inspection hole on a 170A does not line up with the plug as it does on the 170B. The hole is slightly offset. So one can't just install a sump valve.

I like what someone did with the AN fittings to accomplish the quick drain installation. One reason my 170A does not have such a valve is I never wanted to drill another hole in the belly.