Who do we like for Carb Overhaul/Troubleshooting?

I posted of problems in another thread and my IA concluded the carb is coming off the engine.

Where is a good place to send it for troubleshooting/repair/overhaul? I had heard there's a place in Tulsa but there are two listed: Aircraft Accessories of Oklahoma and Quality Aircraft Accessories. It looks like the second one sends it's overhaul work out. It's an MA-4.

I'm not committed to either place. Any other suggestions? Thanks.

I just did mine a short time ago. Quality Aircraft Services has them in stock ready to go. They will send you one and you will get refunded a core charge when they get yours. Very simple and fast!

I just swapped mine out in order to eliminate an old AD. I ordered an overhauled one from Aircraft Spruce. There was a core charge as well.

Yup, when you use spruce, they get them from Q.A.S.

Fish Creek Airmotive in Palmer AK is good.

In researching this I am coming to the conclusion that there really are not very many shops who specialize any more. I called one in Tulsa and the basic overhaul was going to cost more than a replacement carb (already overhauled) from any major supplier! So I am replacing mine. A shame, but I have no particular commitment to this carb.

You will be back in business in a hurry and we're supposed to be getting some nice wx next week!

aviationinfo said:

In researching this I am coming to the conclusion that there really are not very many shops who specialize any more. I called one in Tulsa and the basic overhaul was going to cost more than a replacement carb (already overhauled) from any major supplier! So I am replacing mine. A shame, but I have no particular commitment to this carb.

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It is a shame that a local mechanic can't overhaul the carb. Years ago, when I was working as a full time A&P, that was a normal situation. Parts were readily available. It was not, and should not be, a big deal. There is not very much in a carburetor, or a magneto, which can't be repaired on your bench. There is no guarantee that the exchange carb will be any better than the one you send out. (Been there, done that. A lot of wasted time.)

No one can just fix anything via their repair station limitations anymore. Frustration that you have to pay for an overhaul. Call Bobby at Aircraft Carburetor and Fuel Injection http://www.aircraftcarbs.com/ Used him 20 plus years on carbs on the R3350 down to little Strombergs.

Steve, That is a limitation of possessing a repair station certificate. An A&P could get away with it.

Yes, I agree. A lot of A&Ps don't have the knowledge or the tools to do the work correctly. I like finding magneto and carburetor shops who can repair just what is wrong. Cylinders are another issue. Do valve seats, guides etc here locally cause the cylinder shops want to do a complete overhaul. Sometimes it is just needs to be fixed.

I once had a motor cycle collector bring me a magneto from an Ariel Square Four, which would not produce any spark. I managed to fix it for him, without needing any parts. It was only a magneto, not complicated. They are all basically the same.

Thanks Steve and Skywagon, I completely agree that it should be an easy task for an overhaul shop and understand that the average A&P doesn't mess with them a lot. This carb has been on the airplane for only 5 years so I thought twice about getting an overhauled one again, although this particular one came from Kelly Aerospace which I was recently told had some quality control issues about that time.

The thing that pushed me over the edge completely is that an overhaul kit is roughly $400 without labor, and an overhauled carb from Chief is $715 with a returned core. Although many local A&P's no longer take on carbs, we should probably be thankful that there are businesses that still specialize in these ancient designs so end users like me can still at least get overhauled ones.

I would call Kelly. I have had the fix their work out of warranty free of charge.

The cost of parts issue was why I sent a set of magnetoes to AircraftMagneto Services in Washington State. They had servicable rotating magnets that would have cost more than new mags had I bought new.

aviationinfo said:

The thing that pushed me over the edge completely is that an overhaul kit is roughly $400 without labor, and an overhauled carb from Chief is $715 with a returned core. Although many local A&P's no longer take on carbs, we should probably be thankful that there are businesses that still specialize in these ancient designs so end users like me can still at least get overhauled ones.

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I am saddened by this whole discussion. It is likely some simple little inexpensive thing. If you ever find what it is, would you please report back here for we who are curious?

skywagon8a said:

I am saddened by this whole discussion. It is likely some simple little inexpensive thing. If you ever find what it is, would you please report back here for we who are curious?

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Skywagon I agree with you completely. Will do my best.

Boy, do I ever agree with Steve and Sky. A five year carb probably has a speck of dirt in the idle circuit. I just watched a set of 600- hour mags get sent to an overhaul shop for a simple impulse check that is no longer required. They had to rebuild the entire mag on each. The owner bought Slicks instead.

And what I wouldn't give for a simple seat grinder! I know they are simple - we ground a seat one pleasant evening in Fabens Texas while playing guitar and drinking wine. Just a few stones, a thing that bolts into the valve guide, and an electric motor. Good company!

Bob and aviationinfo,
I can not ever recall needing a complete overhaul kit to repair a carb. Usually just a float valve & seat, an accelerator pump and a parting gasket will do the job. And not always the accelerating pump.

I'm appalled by the prices of airplane carb parts... pulled my Harley carb apart and cleaned it up...parts were $36 aftermarket. I don't buy Harley parts anymore because they are grossly overpriced too. Is there a source for aircraft carb parts (or others) that can be used by EAB builders on a budget? I have a carb that was working fine when removed from the engine and will probably will continue but I would rather rebuild it than take a chance. I'm not an A&P but the one on the 0-320 is simpler than my Harley, dirt bikes, Holleys, Carters, Rodchesters and so on so I think i can handle it...just can't find reasonable priced parts.

Resurrecting this thread.

Replaced the carb. Symptom was fuel all over the lower cowl, apparently coming through the venturi. No
idea what was wrong. Sent it in as a core and included a SASE with a request to let me know, but never heard back.

15 hours on the replacement overhauled carb (this time from Marvel-Schebler, and it's doing the same thing!! Slightly different symptoms though:

I just got home after being away for two weeks to find more fuel dribbled on the lower cowl, but it doesn't appear to be coming from around the carb drain plug like I thought. There's a very small and mostly evaporated puddle on the top of the air box underneath the carb, --forward--of where that drain plug sits. I loosened the air box and the screws are wet, as is the gasket between the air box and the carb. It's wettest at the rear two attachment bolts. I have to wonder if the fuel level is simply too high in the bowl? Or, if fuel is somehow seeping out at the drain plug and getting splashed all over the place? The engine hasn't been run since I left. But it's weird that the fuel puddle is __forward__of that drain plug, as the plane sits nose high. That makes me think it's seeping out of the carb bowl someplace.

And yet, it's totally clean where the bowl attaches. Could it seep into the venturi then drip down somehow onto the airbox and then out? And could the wet air box attachment bolts be from fuel being spread around by the running engine?


The engine runs absolutely fine. These symptoms are nearly identical to the previous carb, except that this one only has 15 hours on it since overhaul. I wonder if they adjusted the float level for the carb sitting level, and not in a nose-high position as for my PA-12? I wonder how bad is it to have the float level be too high, if that's the issue? The engine is not flooding or giving any symptoms other than these fuel stains. Some of the time it's worse than other times. Just weird. I kind of need to at least come up with a theory.

Thanks for your thoughts. I will NOT be replacing this carb. If it's going anywhere it'll be down to that carb shop in TX that Steve mentioned.

I can think of two possibilities. The float is hitting and hanging up on the edges of the bowl holding the needle off it's seat, or there is a defective seal on the needle. Both of which will allow fuel to seep into the bowl, overfilling and running out the nozzle, down the venturi and collect as you describe. The vibration of the running engine will ignore these two problems enough so that the engine runs fine. If the needle has a small leak, less than the running fuel flow, the engine will not know the difference. The needle only stops the fuel flow when the engine is not running. Just thought of a third unlikely possibility, the cotter pin maybe was left off the float pivot pin causing the float pivot to hang up?

I had a brand new 1975 Cessna 180 with carb troubles, from the beginning when I picked it up at Wichita. We found that the needle had a groove worn completely around the circumference causing leakage around the valve. This was brand new from Cessna/Continental! Had a friend who sent his carb to Kelly for an exchange for a problem. The exchange had to be sent back twice before the problem was solved. Needless to say, I do not trust any "overhauler" of carburetors. I hope that your A&P feels comfortable in looking into yours.

Since you have only used it for 15 hours, it seems to me that the overhauler owes you a solution.

You might put the tail up on blocks after you run it next. If it doesn't leak in a level position that would reinforce a misadjusted float.

Excellent ideas both of you. Many thanks! I bet that based on Skywagon's ideas what I'm seeing on the belly after running the engine is simply splatter from what had collected while the engine was shut down.

Yep, sounds like a needle and seat problem to me like on so many Strombergs. I would contact Marvel Schebler, I have usually had good luck getting a vendor to fix their product when there is an issue.

If a piece of crud makes it through the filter screen(s), could that get in the way of the needle seating properly?

There is a very fine screen in the gascoaltor and the carburetor inlet so I doubt it.

I had the same problem. Caused by the primer check valve leaking. Fuel runs out of the primer into the primer nozzle into the intake port and down the intake tube and out the carb throat and around the air box to carb interface.

Was ready to pull the carb and send it to Bobby at Aircraft carb in Dallas when he said to me "have you checked the primer" duh no. The fuel tank will gravity feed thru the primer if the the check-ball is unseated. That was what was happening.

www.aircraftcarbs.com