I have been fighting a leaking carburator. It is leaking from what looks to be about a 3/16" hole in the bottom rear of the throat. The hole is slightly offset to the right side. The leak is just a slow drip but still unacceptable. My question is, what is this hole for? It has been too long since A&P school, I can't recall what it does. I just finished replacing the needle and seat because it was leaking badly. I also adjusted the float level to 7/32". Any thoughts guys?
Shawn
Carburetor leak
Moderators: GAHorn, Karl Towle, Bruce Fenstermacher
I just can't determine from your description to what you are referring. The leak might be caused by a leaking pump discharge check valve or the mixture metering valve assy. Either way will probably require a tear-down and rebuild. Consolodated is the overhauler of my preference. I've heard too many complaints of rough running on Precision overhauls.
If you prefer a small shop rebuild that does quality work, I'd recommend Bill Hatfield in Houston. (800/392-4929) He's been in business for 40 years and has a proper flow-bench for carbs. (He's the one selected to overhaul the Howard Hughes Amphibian Sikorsky (the one found in the bottom of Lake Mead) carbs when no one in the country could get them running. That airplane can be seen flying in to most of the airshows in the Southwest now.)
Bill is also the guy that NASA selected to rebuild generators for their aircraft after their "sting" operation a few years back. (NASA had sent some brand-new generators out to some two-dozen shops for overhaul. There was nothing wrong with the new gens, it was a test to see who would actually comply with the overhaul spec's and replace ALL the parts called for. Bill's shop was the only one who sent them a certified letter informing them that the only fault found was that the gens were in need of recertification due to shelf-life expiration, and when NASA confirmed they wanted them overhauled as per the work order, Bill did so and returned them with all the brand-new, never-run parts he'd removed in a baggie. His shop was the only one who didn't try to re-use the bearings/brushes that were already installed. Bill got a commendation from NASA and the others got an investigation from the FSDO.) Moral: Don't ask Bill to do something unless you want it done, ...and if you ask for something foolish, I've found that Bill will make you confirm that's what you really want. (I sent a friend with a troublesome Bonanza fuel-control to him that Beech (Raytheon) had fooled with for two weeks and he sent it back because he tested it as OK before working on it. The short version of this story is that he ended up teaching the Beech shop how to adjust a Bonanza's fuel system.) He's not cheap, but he's cheaper'n unknowlegeable Bonanza "society" mechanics.
If you prefer a small shop rebuild that does quality work, I'd recommend Bill Hatfield in Houston. (800/392-4929) He's been in business for 40 years and has a proper flow-bench for carbs. (He's the one selected to overhaul the Howard Hughes Amphibian Sikorsky (the one found in the bottom of Lake Mead) carbs when no one in the country could get them running. That airplane can be seen flying in to most of the airshows in the Southwest now.)
Bill is also the guy that NASA selected to rebuild generators for their aircraft after their "sting" operation a few years back. (NASA had sent some brand-new generators out to some two-dozen shops for overhaul. There was nothing wrong with the new gens, it was a test to see who would actually comply with the overhaul spec's and replace ALL the parts called for. Bill's shop was the only one who sent them a certified letter informing them that the only fault found was that the gens were in need of recertification due to shelf-life expiration, and when NASA confirmed they wanted them overhauled as per the work order, Bill did so and returned them with all the brand-new, never-run parts he'd removed in a baggie. His shop was the only one who didn't try to re-use the bearings/brushes that were already installed. Bill got a commendation from NASA and the others got an investigation from the FSDO.) Moral: Don't ask Bill to do something unless you want it done, ...and if you ask for something foolish, I've found that Bill will make you confirm that's what you really want. (I sent a friend with a troublesome Bonanza fuel-control to him that Beech (Raytheon) had fooled with for two weeks and he sent it back because he tested it as OK before working on it. The short version of this story is that he ended up teaching the Beech shop how to adjust a Bonanza's fuel system.) He's not cheap, but he's cheaper'n unknowlegeable Bonanza "society" mechanics.
Thanks George. I dug out some of my old A&P school books and found a blow up of the carb with everything labeled. It is kind of hard to tell in the picture but it looked like it might be part of the idle circuit. Ether way I am wondering if that new needle and seat is leaking around the threads. Do you usually just put them in dry with the aluminum washer or do you use fuel lube as well?
Shawn
Shawn