[YellowJacket RV9]

Shortly after my CI (during which I checked and re-installed the fuel inlet strainer), I noticed some blue staining under the fuel line inlet on my MA4SPA carburetor. Tried ensuring everything was nice and snug, but the leak appears to have persisted or even slightly worsened. Wondering if anybody else has had this leak and how they tackled it. I did use the correct new copper gasket and specified torques. I am considering removing the fitting and tightening down the 45 degree AN823-6D elbow that is attached to it, in case the leak is there. I believe that fitting used some Pematex #2, but will need to double-check.

Thanks

Chris

 

[TS Flightlines]

Shortly after my CI (during which I checked and re-installed the fuel inlet strainer), I noticed some blue staining under the fuel line inlet on my MA4SPA carburetor. Tried ensuring everything was nice and snug, but the leak appears to have persisted or even slightly worsened. Wondering if anybody else has had this leak and how they tackled it. I did use the correct new copper gasket and specified torques. I am considering removing the fitting and tightening down the 45 degree AN823-6D elbow that is attached to it, in case the leak is there. I believe that fitting used some Pematex #2, but will need to double-check.

Thanks

Chris

Chris----if you didnt remove the elbow, I would think the leak is NOT here, but at the bushing connection. if it wasnt leaking before, and is now--then obviously something is different----perhaps the new crush gasket isnt compressing.

 

[YellowJacket RV9]

Chris----if you didnt remove the elbow, I would think the leak is NOT here, but at the bushing connection. if it wasnt leaking before, and is now--then obviously something is different----perhaps the new crush gasket isnt compressing.

Thanks Tom - good point! I ordered a couple new crush gaskets and will take another look to make sure the mating surfaces are clean.

 

[koupster]

Thanks Tom - good point! I ordered a couple new crush gaskets and will take another look to make sure the mating surfaces are clean.

Chris,
In the meantime, to isolate the leak, you could clean away the blue stain, turn on the boost pump, and check for new leakage with a Q-tip. I've found that a small leak can be detected earlier with a Q-tip than waiting for the stain to appear on the metal surface.

 

[YellowJacket RV9]

Chris,
In the meantime, to isolate the leak, you could clean away the blue stain, turn on the boost pump, and check for new leakage with a Q-tip. I've found that a small leak can be detected earlier with a Q-tip than waiting for the stain to appear on the metal surface.

Great idea. Leak never showed up on initial check after the CI under pressure so it is definitely small. Thanks!

 

[YellowJacket RV9]

I cleaned the stains off the carb body today, slightly tightened the inlet fitting, and ran the boost pump for several minutes. No sign of any leaks anywhere. Satisfied, I buttoned up and went for a 30 minute flight. Checked again when I got back, and found more blue stain. This time, it almost looks like the leak may be coming from around the head of one of the bolts into the bowl. Doesn't look to be coming from around the gasket. Is a leak here possible? I assume a fix will just mean dropping the carb and tightening that bolt up a tad. Not the end of the world, but wanted to make sure I'm not missing another possible source. Thanks

Chris

 

[koupster]

Chris,

I see blue stains on the fitting that goes into the carb. Possibly, they didn't get cleaned off before your flight, or, perhaps, the fitting leaked and airflow blew the fuel over the carb body. Yes, it could have gone uphill a bit.
The picture is not clear enough to tell if the stain goes all the way up under the locking tab on that carb bolt.