Fuel in OIl...?

fiveoboy01

fiveoboy01

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Dirty B
I just received the results from my second oil analysis since the overhaul. Good news is that all the wesr metals and silicon have dropped a bunch, bad news is that the fuel was 3.5%....

Last sample the fuel measurement was Trace.

Samples taken at 10 hours and 36 hours. 20W-50 type M.

Viscosity slightly low on both samples at 76 and 79. But I'm more concerned about the fuel.

Possible causes? Take any action, or see what the results are in another 25 hours? Resample sooner?
 
Don't know about aircraft but this happened on the 2001-2004 Duramax motors due to leaking injector seals. The fuel would cause the low viscosity and would increase the oil level due to the addition of fuel in oil. Left unaddressed they would spin bearings due to lack of adequate lubrication.

Are you O or IO?
 
Carbureted or fuel injected?

I ALWAYS had fuel in the oil on my last "engine run" before overhaul. I always attributed it to my propensity to prime too much. It was always higher if I took a short flight just to warm up the oil before changing it.

So, I'd not prime on that flight if it was warm enough to not do so, and the fuel in the oil would come back down to normal levels.

So, I never worried about it.
 
"Fuel in Oil" reminds me of a customer who told me the engine he was buying was for his daughter's car.

As any good father would, he provided the sage advice to always keep the Fuel and Oil topped off.

Unfortunately, the cute blond daughter heard the word "in" not "and".
 
0360..

My Archer has the short stroke primer so I do 6-7 shots when cold. I will try less. Over-priming came to mind, but, the fuel did not show up in the first sample. Maybe I can even get it to start warm without priming.

Also, this sample was taken with everything cold. I let it drain for a bit before taking the sample but the airplane had not been flown. I know, I know, fly it before an oil change, but circumstances and my poor planning prevented it. Not sure what that might have had to do with it, if anything.
 
AggieMike88 said:
"Fuel in Oil" reminds me of a customer who told me the engine he was buying was for his daughter's car.

As any good father would, he provided the sage advice to always keep the Fuel and Oil topped off.

Unfortunately, the cute blond daughter heard the word "in" not "and".
Click to expand...
8ab7f3c8daacf54753352b3213ded443.jpg
 
Are you sure the engine driven pump was replaced at overhaul? I would assume it was, but some folks don't replace/overhaul all accessories. Even new, it could possibly be a manufacturing defect.
 
Yes, everything was new or reman except the starter which I did not send with the engine.

I agree that anything can fail even new. I'm tempted to run 25 hours(4 down already) and resample, prime less, sample it when hot, see if this was an anomaly. I'm not sure that it could be a priming issue though. The first sample showed a trace which is virtually nothing... And my priming habits were the same.
 
Your Lycoming engine pump has redundant diaphragms to keep oil out of the fuel and vice-versa. Theres an airspace and drain tube fitting between them to indicate failure. See if there's any evidence of fuel at the drain. If not, it's pretty unlikely it's the pump.
 
denverpilot said:
8ab7f3c8daacf54753352b3213ded443.jpg
Click to expand...

Oh, my. My younger son bought his first car a couple of years ago. (He's 23 now.) I reminded him about keeping the oil up. The car has 240K miles on it but was pretty well maintained by my father. He asked me about his car because he kept checking the dipstick and the oil is full but the oil pressure light was flickering. I went out with him and saw him check the dipstick. For the transmission. We put 3 quarts of oil in a Toyota 3.0L V6. Holds just over 4 full. The light went out. He's learning...
 
AggieMike88 said:
"Fuel in Oil" reminds me of a customer who told me the engine he was buying was for his daughter's car.

As any good father would, he provided the sage advice to always keep the Fuel and Oil topped off.

Unfortunately, the cute blond daughter heard the word "in" not "and".
Click to expand...

Had a kid at my high school "fill 'er to the top" with oil in his 80s import-right up to the bottom of the filler cap...
 
Did the original question get answered? Can we now wander off into thread drift land?

A buddy came by one day with a Fiat station wagon that had pretty bad rod knock. He got a real good deal on it from some guy who claimed that the vehicle was defective from the factory and blah blah blah and just wanted to get rid of it. The buddy (who was well known at the local Fiat dealer for various reasons) tears it down, and goes to the dealer for parts and gets into a conversation about what he bought - the dealer remembered the car.

The original owner bought it, drove and drove and drove. Apparently never changed or checked the oil. Now, this was a Fiat. They use oil (or, at least they did back then). After a while, it starts to make noise. The noise gets worse. A rod goes through the side of the block. Somehow, the owner manages to get the dealer to fix it because it was defective and he had maintained it properly etc. The owner drives it home with a new engine. And drives, drives, drives. After a while the rods start clattering again. The owner, having learned from the last time, and adds oil - except that the rod knock doesn't go away. Imagine that! He goes back to the dealer claiming that the second engine was defective as evidenced by the fact that the rod knock didn't go away even after he added the oil... He didn't get far with that claim. He vows to never buy another Fiat again. I'm sure the dealer breathed a sigh of relief.
​
 
Zip tied a bag over the vent line and ran for 10 minutes at 1200 RPM. Not a drop of anything in the bag...
 
I was told that if the pump failed, some fuel would exit the vent line.

Anyways doesn't matter, Zephyr overnighted me a new pump and I had it installed this afternoon.
 
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