SAF-AIR oil drain valve leak

FORANE

FORANE

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I have a SAF-AIR oil drain valve like pictured here. With the cowling off for routine maintenance and inspection I noticed a little oil on the top lip of the blue portion. There was not enough to produce a drip, just enough to coat the top lip of the blue. Considering it might have just flowed down from a leak above, I cleaned it but it was back within a couple days time.

There is no oil leaking from the center lumen of the blue where oil drains at the bottom of the valve.

I know these have at least one O-ring. Aircraft spruce lists two different O-rings:

O-RING MS28775-01105-02571$0.21
 O-RINGS AN6227B-705-02572$0.23


Questions are, do these valves take two O-rings?
Which O-ring would I need?
Would one O-ring likely cause a leak as I describe?
I have a Lycoming O-320A.
 
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I am betting it is the crush washer and not the internal O ring...
 
Thanks for the link. I think I have a P5000 so it looks like it has 3 O-rings...
Wonder how difficult this will be.
 
N801BH said:
I am betting it is the crush washer and not the internal O ring...
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May be the crush washer - I thought it might be that also. Interesting the SAF-AIR website does not reference a crush washer part number. I guess I have a trip to Napa auto parts aircraft division...
 
If it's not leaking out of the center hole in the bottom, it's not an O-ring leak. It's either the crush washer, if it has one, or if that valve is a half-inch pipe thread, it won't have the crush gasket and the pipe threads need resealing. Don't just tighten the valve or you might crack the crankcase sump.

Dan
 
Dan Thomas said:
If it's not leaking out of the center hole in the bottom, it's not an O-ring leak. It's either the crush washer, if it has one, or if that valve is a half-inch pipe thread, it won't have the crush gasket and the pipe threads need resealing. Don't just tighten the valve or you might crack the crankcase sump.

Dan
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Dan

Thanks for the post.
I would have sworn it had a crush washer. Your post spurred me to drive to the plane and take a closer look, and a pic... No washer, just 1/2 NPT.
What is the preferred technique for resealing pipe threads?

And, how do I attach a larger pic than a thumbnail?
 

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Jeff Oslick said:
Did you check that the check valve is properly torqued?
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Nope.
What would that torque value be?
By check valve, you are referring to the stainless top portion of the SAF-AIR valve which screws into the oil pan correct?
 
FORANE said:
Nope.
What would that torque value be?
By check valve, you are referring to the stainless top portion of the SAF-AIR valve which screws into the oil pan correct?
Click to expand...

Industrial applications will call for 40 or 50 foot-pounds, which will crack that aluminum case for sure. I wouldn't use more than 15 foot-pounds, or 180 inch-pounds. NPT threads aren't even usually lockwired on airplanes, but this one is, so the likelihood of it backing out is almost nonexistent. All it's doing, after all, is keeping oil from escaping under gravity pressure; we're not talking 3000 psi here.

Use Permatex Form-A-Gasket for a sealant. Don't use teflon tape and ESPECIALLY NOT silicone sealant. Teflon shreds and gets into stuff, and silicone forms little gobs that can cause issues inside the engine. When I was in the air brake rebuilding industry, we had far too many components come back all fouled up with silicone. Compressors, especially, were sometimes blown to bits due to silicone getting into crankshaft oil galleries. The screens in the Lycoming should prevent that, but it still gives me the creeps. The screens won't keep it from fouling that drain valve next oil change, for instance, and making it leak.

By the vise-grip or pipe-wrench marks on that valve, I'd have a look at it to see if it's been squeezed out-of-round, which will make it leak at the threads. It was probably stuck really tight in the last engine and the guy had to use something brutal to get it out.

Dan
 
Dan Thomas said:
......
By the vise-grip or pipe-wrench marks on that valve, I'd have a look at it to see if it's been squeezed out-of-round, which will make it leak at the threads. It was probably stuck really tight in the last engine and the guy had to use something brutal to get it out.

Dan
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Yeah... I saw those marks too.... You would figure any decent A&P would have used a deep socket to remove that valve,,, but then we all know some aircraft mechanics are NOT decent , or even smart..:no::nonod::mad2:
 
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