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I got some tiny metal shards in my fuel filter. I've read that after break-in this is usually normal because of the piston setting on to the liner and because of the back pressure of the muffler they go back into the tank. Is that correct? O.S 46AX

Jetdesign

My Feedback: (8)

Good thing you have an inline fuel filter! I know this is common on Evolution engines, where you end up with a gray sludgy stuff that is metal mixed with oil and fuel. I didn't have this problem on my 46AX, but maybe yours came off the line a little different or something. Not totally out of the question, but I'm surprised that happened with an O.S.

combatpigg

My Feedback: (3)

Hi plugin..I have never heard of this problem. Do you have a filter on the pressure line?

plugin

No filter on the pressure line, just a filter behind the needle and this is where I caught the debris. I checked the piston for integrity and it seems brand new. Its got about 30 minutes of run time.

combatpigg

My Feedback: (3)

Nothing but the finest grit could migrate from the exhaust into the tank. I'm surprised to hear that you found metal. It isn't a bad idea to pull the head and backplate off a new engine and do a total cleaning before running it. I have seen filters on pressure lines before and never paid attention to it or questioned it.

plugin

In any case I don't care for the grit to be in the tank as long as the filter is catching it. I'm just concerned and want to know if this is normal.

The Ghost

Do you have any filters on the fueling rig that you use. May not be from the motor at all, but from your fuel supply.

Cheers

Jetdesign

My Feedback: (8)

In my opinion, you've got a brand new, newly machined piston cylinder device operating at somewhere around 13000rpm, which utilizes a compression-fit to seal the combustion chamber, i.e. metal rubbing on metal, so I am not surprised that a metal shard appeared. And yes, back pressure can cause combustion debris to re-enter the fuel system.

Taking apart the engine to clean and inspect it is not a bad idea. Plus it helps you get to know your engine better. Check out this video on youtube, it is a perfect instruction on how to disassemble and reassemble the engine, noting what parts should be lubricated, what kinds of lubricants to use, etc. It is a 2 part video. Obviously you don't need to change your bearings (the title of the video) but you need to take apart the whole engine to get the bearings out, so it's a valid video.

http://youtube.com/watch?v=TuzEco3EDUM
http://youtube.com/watch?v=OLSoXPLGzOI

Good luck.

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Thanks gaRCfield, but I was the one who gave you those links on your bearing thread

Jetdesign

My Feedback: (8)

*Laughing. Oh, thanks. They were great links!!!

Gray Beard

My Feedback: (-1)

Just for grins you may want to take A close look at your clunck on the end of your pick up line inside the fuel tank. If by chance you have one that has been chromed guess what happens.
Those little metal tubes going into your fuel tank that you cut to shorten?? Just something to think about.
Most new fuel tanks are molded two piece plastic, I always put some fuel in them before I assemble them and wash them out. I almost always find little pieces of flashing in them.
It's very hard for metal parts to end up in your tank from the pressure line, nasty gray sluge on A new or old engine is normal.

plugin

I think you've nailed it Gray Beard. Now that I think about it, I did shorten one of the metal tubes and I think that is where the metal is coming from. I'll flush the filter and check with more flights to see if I still get the same particles but my guess is that they in fact are leftover from the metal tube shortening.

Jetdesign

My Feedback: (8)

Nice, hope you found the problem. Again, great reason to have an inline fuel filter!