Hi All,
I have a Van?s Aircraft RV-6, powered by a Lycoming O-320-H2AD, equipped with a Marvel Schebler Carburetor, model MA4SPA, P/N 10-5135, S/N CK 1 1828, overhauled in 1994, with almost 930 h since then.
The other day I flew for about 40 min. About 20 minutes after the flight, with the aircraft already stored in the hangar, I detected fuel dripping by the underside of the cowl. The leak ended soon. Later I found fuel spraying through accelerator pump stem when reducing throttle to idle.
I purchased the standard repair kit plus the float kit and sent the carb to the shop for a complete overhaul.
The carb returned as new.
Installation was straight forward and operation was smooth as before removal.
2 months later, after 10 flights, only 5.5 flight hours, the carb is leaking again on the same point.
I suspected of a mistake durind assembly that could have affected the accelerator pump plunger leather boot.
Removed carb again under shop warranty.
The carb came back from the shop and unfortunately it is leaking again.
I flew for 40 min, 15 minutes after the flight I detected fuel dripping on the floor, the leak ended soon, as before.
How can fuel get to the upper side of the accelerator pump chamber?
Why this would happen while the engine is cooling?
Looks like that fuel gets hot then expands.
Marvel Schebler online support told me they believe that the pump stem packing may not have been staked tight enough into the casting at overhaul.
Someone can help?
Thanks,
Ramiro
I have a Van?s Aircraft RV-6, powered by a Lycoming O-320-H2AD, equipped with a Marvel Schebler Carburetor, model MA4SPA, P/N 10-5135, S/N CK 1 1828, overhauled in 1994, with almost 930 h since then.
The other day I flew for about 40 min. About 20 minutes after the flight, with the aircraft already stored in the hangar, I detected fuel dripping by the underside of the cowl. The leak ended soon. Later I found fuel spraying through accelerator pump stem when reducing throttle to idle.
I purchased the standard repair kit plus the float kit and sent the carb to the shop for a complete overhaul.
The carb returned as new.
Installation was straight forward and operation was smooth as before removal.
2 months later, after 10 flights, only 5.5 flight hours, the carb is leaking again on the same point.
I suspected of a mistake durind assembly that could have affected the accelerator pump plunger leather boot.
Removed carb again under shop warranty.
The carb came back from the shop and unfortunately it is leaking again.
I flew for 40 min, 15 minutes after the flight I detected fuel dripping on the floor, the leak ended soon, as before.
How can fuel get to the upper side of the accelerator pump chamber?
Why this would happen while the engine is cooling?
Looks like that fuel gets hot then expands.
Marvel Schebler online support told me they believe that the pump stem packing may not have been staked tight enough into the casting at overhaul.
Someone can help?
Thanks,
Ramiro
Ma 3spa Manual
Marvel Schebler Carburetor Ma 3spa
MA-3™, MA-3A™, MA-3PA™, MA-3SPA™, MA-4™, MA-4SPA™, MA-4-5™, MA-5™, MA-5AA™. Carburetor service manual; remove the bowl from the throttle body. Appropriate service manual. Secure the lock tab washers by bending the tabs. E) Reinstall the carburetor on the engine and rig it in accordance with the applicable. SERVICE MANUAL MODELS MA3A MA3PA MA3SPA-MA4SPA PNECIIIIDN. Models MA 3A, MA 3PA, MA 3SPA, and MA 4SPA are very similar and this overhaul section will apply to all. Operator's Manual Lycoming O-235 and O-290 Series Approved by FAA 5th Edition Part No. 60297-9 652 Oliver Street January 2007 Williamsport, PA.