Leaking Fuel Primer

[DanBrown]

On starting up after a long down time, I found that my primer leaked fuel. On taking it apart, we found the leather seals had disintegrated.

Buel Powell had a post last year:

"What may be the problem is the seals on the primer shaft may allow the primer not to seal and allow it to continue to draw fuel from the gascolator. Most primers have rubber O'rings that are very easy to replace. My original had leather cup seals which I didn't like so I replaced the primer with a modern one. "

Does anyone know where to get the modern replacement and what the part number is?

Thanks,

[astjp2]

Re: Leaking Fuel Primer

Just do a search on www.aircraftspruce.com or www.wicksaircraft.com, they have them. Tim

[Buell Powell]

Re: Leaking Fuel Primer

The one I used is a Kohler. The hole has to be enlarged to mount it and the knob is larger and is close to rubbing the upper inst panel when pulled but just clears.

[whake]

Re: Leaking Fuel Primer

Take a look at Ebay, if you have a Lunkeheimer primer you will need a cord seal. A good old old old hardware store may have one..

[Guest]

Re: Leaking Fuel Primer

Anybody remember the o-ring size(s) needed and the count for a Kohler primer?

I drained the fuel from my airplane a few months ago to work on it and now refilled it but it appears that the primer leaks now.

Dave

[astjp2]

Re: Leaking Fuel Primer

before you get all wild with the Orings, get some fuel lube and use it, maybe the Orings are just dry. Tim

[tabranch]

Re: Leaking Fuel Primer

Anybody remember the o-ring size(s) needed and the count for a Kohler primer?

I drained the fuel from my airplane a few months ago to work on it and now refilled it but it appears that the primer leaks now.

Dave

The correct size is MS29513-012 and the quantity is 2!

[Guest]

Re: Leaking Fuel Primer

Thanks Tom!

[Guest]

Re: Leaking Fuel Primer

I put new o-ring seals in today. Old ones were flat, had nicks and deformed.

It appears to have stopped the leak.

Here's the question. Why would a bad o-ring cause the primer to leak fuel into the manifold when the fuel was on and the primer was locked?

I haven't touched a primer in a long time and am a little rusty about the details. Its a Kohler primer.

So far I can't find a schematic of a primer in any of my A&P books.

I am thinking the springloaded needle at the end plunger might have more to do with this type of problem. Does that make sense?

I am kinda expecting the leak to reappear. I didn't wait a long time to see if it stopped so it may "reappear".

Any advice is appreciated.

Thanks, Dave.

[N96290]

Re: Leaking Fuel Primer

Was going to get some more of the tail wheel check out done yesterday as it was about 40 Deg F and wind was not too bad. When I opened the door to start the preflight I was greeted with a nice gas smell and found the primer was dripping. I removed the primer and plugged the lines but decided to let it dry up and air out a few days before lighting the fire up front. The leather cups look fair but it leaked like a seive and that might explain why it seems to take about eight shots of prime before you get enough fuel in it to light off. It was just barely working. I ordered a Koler primer to update a bit. Now it looks like the valve from the main tank is not shutting off completely which allowed that much leakage with the valve closed. There was some discussion on that a while back but being as how I was a tri-pacer driver and only checking out options I didnt pay much attention. Are these repairable or what is the best replacement.