Hi Richard The question is not whether the lines need to be free of air, but how. I top up my Racors from diesel poured into a 2 gallon container bought just for that purpose, filling the container when I buy fuel. Once you've completed the changeover, if you're lucky, you can crack the bleed screw on the injector pump - there are two on the Simms, and in my case the engine is canted to the rear just enough that I must/must crack the forward one - just a bit, and hope that once started, the engine will run well enough bleed all the air from the system automatically. If not, since I use the original lift pumps rather than electrical, it takes about 50 thumb presses to purge the system completely. (Wear a glove.) I did change the engine mounted filters the first time, but will now do so only about every third or fourth year. Since the Racors are 2 micron and the engine mounted canisters are 10, they simply can't get dirty. Cheers, Garrett

> I top up my Racors from diesel poured into a 2 gallon container bought > just for that purpose, filling the container when I buy fuel. Once > you've completed the changeover, if you're lucky, you can crack the > bleed screw on the injector pump With respect, the following method might work better for some. You have turned off the fuel lines to and from the primary filter you are changing. You change the filter. The fuel level will now be out of sight because of the fuel that came out with the old filter. You crack the tap on the tank side and simply watch for the fuel level to get to the top of the filter cylinder. Replace the top and you are done. No air, no bleed, no separate tank of top-up diesel, and little mess. Return all taps to normal operating position, final check for leaks, and you are off. Richard