Carb gas drip Lycoming O-320

[rvator51]

When doing the condition inspection this week, one of the tests I did was to check that the engine would shut off by turning off the ignition switch which verifys the magneto grounding.
After the engine died, the carb started leaking gas through the air box. I could get it shut off by pulling back the mixture control. Moving the mixture forward again would start the leak back up. This happened several times and after running shutting of the engine a few times, the leak stopped and doesnt come back by moving the mixture forward again.

Wondered if anyone had encountered this scenerio before? I drained the carb afterwards and didnt see any contamination in the gas.

[Mark Burns]

Originally Posted by rvator51

When doing the condition inspection this week, one of the tests I did was to check that the engine would shut off by turning off the ignition switch which verifys the magneto grounding.
After the engine died, the carb started leaking gas through the air box. I could get it shut off by pulling back the mixture control. Moving the mixture forward again would start the leak back up. This happened several times and after running shutting of the engine a few times, the leak stopped and doesnt come back by moving the mixture forward again.

Wondered if anyone had encountered this scenerio before? I drained the carb afterwards and didnt see any contamination in the gas.

Tom,
It's most likely the needle valve on the float. It's got a rubber tip. Maybe something stuck on it. How old is the carb? The rubber tip may have a "ring" worn into it. Mine did the same thing a few times. I ordered a new needle valve kit. I've yet to put it in I've just been turning the fuel off at shutdown, just in case it decides to leak again. Once the engine is running it's not an issue.

Mark

[rvator51]

Hi Mark,

Its a newer 10-5217 carb that I bought from overhauled from Chief? about a year ago.

I will look at the needle valve when I open it up tomorrow.
Thanks!

[osxuser]

Actually, often it can just be the copper gasket that the nozzle torques onto. I've run into a couple of these that were mis-seated or deformed straight from overhaul (Kelly aerospace ). Seems to be worse with the geometry of a TD.

[Jeff Vaughan]

I recently had this problem with my new carb of 43 hours. I had sent it to Tempest to have the SB Float changed. Reinstalled it and the next day it was leaking. I returned it to tempest and they replaced the needle valve.
Now 72 hours and no leaks

[rvator51]

We removed the carb and opened up the float bowl. Nothing obvious showed. Cleaned needle valve and check float height setting. Reassembled and now cant get carb to leak. Will watch closely to see if problem returns.
Thanks for everyones help!