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PhatRV

Well Known Member
While fitting the fuel lines in my RV8 yesterday, about 1 tablespoon of the oil inside the Airflow Performance fuel pump leaked out. I think the oil is to keep the pump lubricated and cool before fuel is pumped through it. Should I be concerned with amount of oil that escaped from the pump?

Thanks.
 
it is a preservative oil and will cause no issues. Any remaining oil after that first purge will easily mix with the gas and not cause any problems. I recommend disconnecting the line at the carb/servo and running a gallon of fuel into a bucket to flush out debris before first engine start. This step can also perform the recommended fuel flow test.

Larry
 
lr172 said:
it is a preservative oil and will cause no issues.
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Resurrecting this thread as I was getting ready to test fit my fuel line fittings/valve and had oil unexpectedly leak out when I unscrewed the rear temporary cap on the fuel pump. What the heck? I couldn't find any mention of this oil on the AirFlow Performance website or in their manual.

Question-
If all of this preservative oil leaks out, is that a problem if I don't fly this airplane for 2-3 years?
 
No guarantees, but you should be ok. The time between buying my pump and finally flying was 10 years and now two years into operations and everything is still working as advertised. Its not ideal of course, but it happens. I live in a very dry and corrosion-free environment though. YMMV.

I avoided running the pump during the build process. It had one short blip to ensure the wiring was correct once it was installed and then nothing until the fuel system was "wet".
 
I'm not sure what the "winning strategy" is with the fuel pump. I installed mine in the airplane (on the -10) at least 3 years before first engine start. The pump was frozen when I went to use it. The folks at Airflow said the preservation oil residue had hardened and seized the pump.

So maybe the approach should be to keep the pump on the shelf and full of oil until very late in the assembly process.
 
After the initial oil spill, the fuel outlet lines were opened to the element until the engine was hung which was about 8 months after I asked the question. The pump outlet was sealled against the outside air after the fuel line was connected to the engine. The inlet side was sealed to the Andair fuel selector. This fuel selector was removed only in a few times when I was fitting the wings. The first time the pump was powered on was 3 years later to perform the fuel flow test and so far it performed nominally during my phase 1 testing almost 1 year after the initial test.

So I think the key is to seal the pump outlets as well as you can to prevent the lubricant from drying out. Using AN cap fitting should keep it in preservation state for a long time.
 
bertschb said:
Was the preservative oil drained out of it during that time?
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I most certainly didn't drain any oil out but then I don't recall there being much in there to begin with. I did recognize there was a small dribble at the beginning... maybe half a teaspoon full? Certainly the pump was not "full" of oil at all. I didn't have the issue noted above of the pump seizing either... its been working as expected since day one.
 
I contacted Airflow Performance and asked about the oil that leaked out. He said it is preservative oil. He also said if the oil leaked out he "would recommend filling the pump with light weight oil or ATF, then recap for storage". I also asked how long I could leave the pump with no oil inside. He said "it depends on how much leaked out and the conditions it now sits. If just a little is left in there and it's mostly air, then it can dry up relatively quick".

Why no mention of this oil anywhere? This information should be on their website, in their FAQ's, in their manuals, included in the shipping box, etc. I certainly was not expecting oil to come out of the pump when I unscrewed the cap. I was under the false impression that the fuel system should be kept CLEAN. Now I'll be pumping oil through the fuel lines????? So now I need to know what kind of "light oil" I can use to refill the pump that won't contaminate the fuel lines. Also, how does oil dry up?

Sorry for the rant. Two days ago I completed the "big join". That was a good day! It was followed up by this fuel pump oil mess, trying to find Loctite 648 for the fuel selector valve screws and messing up one of the holes in the fuel selector valve cover plate while countersinking. Today will be better!
 
bertschb said:
I contacted Airflow Performance and asked about the oil that leaked out. He said it is preservative oil. He also said if the oil leaked out he "would recommend filling the pump with light weight oil or ATF, then recap for storage". I also asked how long I could leave the pump with no oil inside. He said "it depends on how much leaked out and the conditions it now sits. If just a little is left in there and it's mostly air, then it can dry up relatively quick".

Why no mention of this oil anywhere? This information should be on their website, in their FAQ's, in their manuals, included in the shipping box, etc. I certainly was not expecting oil to come out of the pump when I unscrewed the cap. I was under the false impression that the fuel system should be kept CLEAN. Now I'll be pumping oil through the fuel lines????? So now I need to know what kind of "light oil" I can use to refill the pump that won't contaminate the fuel lines. Also, how does oil dry up?

Sorry for the rant. Two days ago I completed the "big join". That was a good day! It was followed up by this fuel pump oil mess, trying to find Loctite 648 for the fuel selector valve screws and messing up one of the holes in the fuel selector valve cover plate while countersinking. Today will be better!
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all the oil will be expelled when you do your fuel flow test. The oil doesn't get into the fuel servo or carburator during the test since you will disconnect the fuel line into the fuel servo. Plus it is probably prudent to flush all the debris from the fuel tanks, fuel lines, and all the excess non-fuel liquid from the fuel system before starting the engine. My fuel tanks were relatively clean when I flushed them before the fuel flow test since I cleaned them out before closing the rear baffle. Another RV8 builder found his quickbuild tanks were full of aluminum shavings during the flush. This is something that you have to take care of as a builder. No more hand-holding during this stage.
 
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