Racor Air Gremlin...

[Tim Mertinooke]

I ran the engine today for about an hour and everything worked great from idle all the way up to 3000RPM. My question is about something strange I observed when looking at the racor filter glass reservoir. There was air in the top 1" or so. To try to fix this I stopped the engine, removed the fuel filter cover, and then topped it off with diesel making sure some came out over the top once the filter and cover were placed back on. I then started the engine and within a minute the air was back at the top of the filter. My initial thought was that my fuel line was sucking air, but found no further evidence of this other than the air in the filter. The air in the fuel filter didn't affect the engine performance at all and the air remained at the same volume for as long as I ran the engine. If there were a leak, it seems to me that the air volume would have increased and after a while affected the engine performance. I had replaced the fuel filter and o-rings last weekend and have run the engine now for about two hours without any problems. Any ideas about how to fix this? IS this normal? There shouldn't be any air in the filter, right?

[David VanDenburgh]

Which Racor filter are you using?

[Tim Mertinooke]

Model 200 FG.

I'm starting to think it may be a vaccum that is formed due to the pressure of the fuel system, but I don't know for sure.

[David VanDenburgh]

Tim,

I've got two 500FGs, and I think what you're describing is normal. I can't see the air space through the bowl on my filters, but when I remove the cover the fuel level is about 3/4" to 1" below the top. As long as the outlet remains below the fuel level, all should be okay.

I also have a vague recollection of calling Racor, or someone knowledgeable, and they assured me that the filters were functioning properly. And, so far, no problems.

David

[Tim]

I'm pretty sure that condition is entirely normal and adheres to my recollections of seeing those types of filters in a number of installations. Honestly, though, I've never thought to look specifically at that fuel level, so I can't affirm with authority.

[Rachel]

It sounds as if the air situation is normal, but your mentioning that you have a 500 filter unit reminded me of something you might want to check, just in case it applies, since the filter body is new to you (assuming it came with the boat):

In about 2005, Racor issued a free-for-the-asking spacer (small black plastic doghnut) for certain pre-1997 (if I remember correctly) 500 filter housings. This is because they changed the shape of the elements that fit inside that unit, and without the spacer, the new elements in the old filter bodies will drop down about 1/2" which means that fuel can sneak right past the filter. The spacer makes it so that the new elements ride properly in the old 500 filter bodies. (The newer elements have a recess in the bottom and the doughnut fills this in.)

Rachel

[David VanDenburgh]

In about 2005, Racor issued a free-for-the-asking spacer (small black plastic doghnut) for certain pre-1997 (if I remember correctly) 500 filter housings. This is because they changed the shape of the elements that fit inside that unit, and without the spacer, the new elements in the old filter bodies will drop down about 1/2" which means that fuel can sneak right past the filter. The spacer makes it so that the new elements ride properly in the old 500 filter bodies. (The newer elements have a recess in the bottom and the doughnut fills this in.)

Rachel

Good point.

Yeah, Racor changed filter elements about a year after I installed the new filtration system in Ariel. I picked up a supply of spacers - fuel line cut to size - and installed them during a seasonal filter change.

David