Carb Leak - how serious is this?

Nikhiln25

Nikhiln25

Pre-takeoff checklist
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nikhiln25
Cessna 182 with O-470-U. Carb has fuel leaking from the gaskets it seems. I have my annual scheduled in January and will get this looked at. But I’m the mean time how big of a risk is to flying and anyone have perspective as to what could be causing this?IMG_2471.jpeg
 
I see at least two leak sources on an otherwise clean and new-looking carb. Could it be that the seals/gaskets have compressed and some retorques are required?
I'd have it looked at now, fuel leaks in should not be deferred.
 
Did you ever run mở gas in it. Maybe a little ethanol got in there and swoll up some o rings.
 
AV8R_87 said:
I see at least two leak sources on an otherwise clean and new-looking carb. Could it be that the seals/gaskets have compressed and some retorques are required?
I'd have it looked at now, fuel leaks in should not be deferred.
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Yeah the top one does look like a seal issue, the bottom one is strange. Trying to find and A/P willing to look at this without a month lead (when it goes into annual anyway)
 
Nikhiln25 said:
But I’m the mean time how big of a risk is to flying
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Good question. How much of a risk is acceptable to you?

For now: https://www.expaircraft.com/PDF/marvel-schebler-OH.pdf

That lower half is your fuel bowl. Leak looks like from Part 31 on Fig 2-19, the fuel strainer assembly. That part should be under some pressure from the fuel pump. It looks like the leak drips down, but the additional blue on the lower portion of the bowl might be a separate leak or not (see Fig 2-20).

Causes? Leaky gasket, loosening assembly, crack, any or all.

I would not fly it, but that’s a personal risk aversion.

I am NOT an A&P.
 
Looks like a slight seep to me. On our equipment, small leaks in wide open areas are deferrable. A fuel leak in the engine compartment is a no-go item. I would get it fixed.
 
It certainly looks like it's leaking from the inlet strainer gasket (part number A16-A48, $1.55 from Aircraft Spruce). Replace that, clean everything, see if it fixes it. The staining down lower may be a separate leak but from the location it's likely it's dripping from the leak above.

You can even legally do it yourself, as it falls under "Cleaning or replacing fuel and oil strainers or filter elements."
 
Dana said:
It certainly looks like it's leaking from the inlet strainer gasket (part number A16-A48, $1.55 from Aircraft Spruce). Replace that, clean everything, see if it fixes it. The staining down lower may be a separate leak but from the location it's likely it's dripping from the leak above.

You can even legally do it yourself, as it falls under "Cleaning or replacing fuel and oil strainers or filter elements."
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Thanks - what function does the inlet strainer play in the carburetor ? Hopping to understand this whole thing more
 
Looks to me like the wrong copper washer anyway. Looks like the bottom one is supposed to index on a tab that’s not there, the fingers aren’t bent up.

There may be another stacked on that one… something a little hinky. Not a huge deal, but the ease of repair makes about any risk not worthwhile.
 
Why defer maintenance on a critical component?
 
That gasket is one that should NEVER be re-used.

It’s not a bad idea for the owner to keep a few in the aircraft.
 
Is the plug tight or loose? If its tight I wouldn't sweat that little leakage too much but I would be getting a new gasket for it. I like to put a tiny bit of fuel lube on that when installing them.

Is that thread tape on the bowl drain plug? I don't like that. I just use a tiny bit of fuel lube there too
 
Was it overhauled recently?
I had mine done and that gasket provided to me on the bottom was not the right part. It was close. Looks like the same carb I have.
 
Being on fire at 5000msl over hostile terrain doesn’t sound like fun to me
 
SixPapaCharlie said:
Was it overhauled recently?
I had mine done and that gasket provided to me on the bottom was not the right part. It was close. Looks like the same carb I have.
Click to expand...
Yes it was in 2022.
 
RyanB said:
Why defer maintenance on a critical component?
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Not deferring it.. just trying to figure out what risk it presents before I have it in annual next month
 
Found an A&P who is willing to replace the gasket next week. Seems like that is the only source

Thanks all
 
Nikhiln25 said:
Not deferring it.. just trying to figure out what risk it presents before I have it in annual next month
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FYI: Any active fuel leak is a high risk in the engine compartment especially when you don't know the exact cause.
 
Katamarino said:
Fuel pump...?
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Gravity flow head pressure? Thanks for correcting.

I’m a car guy and all my carbs have fuel pumps. And my 182 is injected.

That’s why I always post the disclaimer that I’m not an A&P…I also don’t know the 0-470’s 182 fuel system
 
This is one of those tasks that can be very frustrating for the Tech.

Particularly if not on site.

Trip 1: Obtain and install the gasket for the Fuel Strainer.

Clean dye on carb and attempt to determine cause of lower stain.


Trip 2: Needed if lower stain returns.

If the lower stain returns it’s possibly cracked and the Carb will have to be removed and sent out.


Trip 3: Install and rig the overhauled carb. Run-up and leak check. Log entry.


The gasket replacement is a rather small item and ABSOLUTELY NECESSARY but it becomes a big deal.

1. Drive to - from several times or pull in- out of shop.

2. Research and order gasket. Rapid delivery not taken for granted anymore. This item is not used on ALL
aircraft so it may not be in stock in some shops.

3. It appears to me the lower stain in from a small seep over a somewhat long time period.
This is based on the accumulation of dye. Identification of the source might be iffy.

4. Will the cowl go back on a couple times before done? Some 182’s are not a joy.


In many locations hangar space is at a premium during winter months so leaving in a shop may not

be feasible. Labor of a move is obvious but another factor can be the heat costs. It can be like putting

a block of ice in the hangar after having the doors open. Folks working on other projects suddenly

drop tools and find warmer surroundings!


If you seen the pic you are using “ Remote “ to aid in troubleshooting. The actual on- task time spent by the

A& P can be minimal but the final billing can be upsetting. IMHO the more a owner can diagnose

and assist in resolving the problem the better it is for all.

No one wants a tag like “ He/she charged me $500 for a 20 minute job”.

That could easily happen here.


Again; NECESSARY to address.
 
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Any leaked fuel above the bowl flange will follow the flange. I’d investigate it with that in mind.
 
Stewartb said:
Magman said:
This is one of those tasks that can be very frustrating for the Tech.

Particularly if not on site.

Trip 1: Obtain and install the gasket for the Fuel Strainer.

Clean dye on carb and attempt to determine cause of lower stain.


Trip 2: Needed if lower stain returns.

If the lower stain returns it’s possibly cracked and the Carb will have to be removed and sent out.


Trip 3: Install and rig the overhauled carb. Run-up and leak check. Log entry.


The gasket replacement is a rather small item and ABSOLUTELY NECESSARY but it becomes a big deal.

1. Drive to - from several times or pull in- out of shop.

2. Research and order gasket. Rapid delivery not taken for granted anymore. This item is not used on ALL
aircraft so it may not be in stock in some shops.

3. It appears to me the lower stain in from a small seep over a somewhat long time period.
This is based on the accumulation of dye. Identification of the source might be iffy.

4. Will the cowl go back on a couple times before done? Some 182’s are not a joy.


In many locations hangar space is at a premium during winter months so leaving in a shop may not

be feasible. Labor of a move is obvious but another factor can be the heat costs. It can be like putting

a block of ice in the hangar after having the doors open. Folks working on other projects suddenly

drop tools and find warmer surroundings!


If you seen the pic you are using “ Remote “ to aid in troubleshooting. The actual on- task time spent by the

A& P can be minimal but the final billing can be upsetting. IMHO the more a owner can diagnose

and assist in resolving the problem the better it is for all.

No one wants a tag like “ He/she charged me $500 for a 20 minute job”.

That could easily happen here.


Again; NECESSARY to address.
Click to expand...
Click to expand...

I sent this pic to an A&P I know and he said he believes it is coming from top gasket and he has that part in stock. I am going to attempt to clean this up before I take this plane to him, to see where the fuel is after clean up and a quick run. Thankfully he’s only a 20 min flight away from me. Not planning on flying until then.

But yeah I am mentally prepared for this. I’m a new aircraft owner so trying to learn as much as I can my self to help him. I think cleaning it up and then flying it to him would help dissect a little bit if there is a second leak or not. Putting the cowling on by my self after taking it off is a bit of a challenge for me since I haven’t really done it
 
Nikhiln25 said:
I’m a new aircraft owner so trying to learn as much as I can my self to help him.
Click to expand...
Three words for you: owner assisted annuals (and maintenance in general). Great way to build a good relationship with an A&P/IA, while learning as much as you can about your plane. Makes you a better pilot, too.
 
Putting the lower cowl on alone is not easy.

Intake Duct in particular.

I’m a believe in sort of a “ Local Type Club” for mutual assistance.

It’s possible there may be another 182 owner that knows the

techniques and “ Special Words”!
 
That bottom leak looks like it might be coming from the "channel plug screw" or a steel ball plug, numbers 20 and 29 respectively.

1734040653540.png
1734040807725.png

Sloppy lockwiring there, too. Not twisted tight enough, and the cut end left out to snag and slash fingers. The other end of the same wire is not snug against the bolt head;

1734040900863.png
 
Dan Thomas said:
That bottom leak looks like it might be coming from the "channel plug screw" or a steel ball plug, numbers 20 and 29 respectively.

View attachment 136123
View attachment 136124

Sloppy lockwiring there, too. Not twisted tight enough, and the cut end left out to snag and slash fingers. The other end of the same wire is not snug against the bolt head;

View attachment 136125
Click to expand...
Interesting. Seems possible it is and just running along the wire to the other end. But I wonder why the dye is staining upwards from the plugs
 
How would one clean this? Just a damp rag or anything special ?
 
The strangest thing here is the dye on the logo for Marvel… that’s not near either leak and has some dye
 
Clean with carb cleaner or brake clean. I’ve been able to clean blue fuel stains off my paint safely with it too, though my paint is old Imron. Fuel might work too, though I’ve only used carb cleaner. Buy cleaner at an auto parts store. Use an old toothbrush to get it all out.
 
If you use brake cleaner, make sure it is the non chlorinated type. The chlorinated cleans better, but is corrosive to aluminum.
 
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