Friday, May 28, 2010

Changing Fuel Filters - Ugh!

I knew the fuel filters needed replacing, but for reaffirmation I checked the log book to see when they were last done. When I was doing lots of cruising I changed the fuel filters about every 200-300 hours which was about once a year. Well my last change was in 2008 and I've put about 200+ hours on them, so it's time.

Changing fuel filters can be a messy, smelly, and complicated job. First you got to remove all the old filters and on the Independence there are 4 of them - a primary fuel/water separator (NAPA 3133), a primary fuel filter (NAPA 3134), and two secondary fuel filters (NAPA 3358). Invariably fuel gets spilled, your hands get soaked with diesel, and then you have to not only replace the filters, but then you have to bleed the system. A diesel will not run if you have even the tiniest of air bubbles in the system. After years and years of doing this job, I got smart and first of all got knee pads. My second smart thing is to take my time. And the third thing I learned is to use a small container to catch the 'old' fuel. Items 1 & 2 are the keys though - knee pads and take your time.

Now on to the job itself... On the Independence you can turn off the fuel using a gate valve (just like your yard water faucets at home). I then one at a time removed the primary filters and surprisingly didn't spill a drop. Then I removed the secondary filters and again didn't spill a drop. Wow, I was doing good. I then took a break and cleaned up the fuel canisters that hold the filters. Hmmm? Not too bad. Then I replaced all the filters in the right order - #1 fuel/water separator, #2 fuel filter, #3 secondary filters. I was about half-way done.

I opened up the fuel valves to each tank. Gravity & weight of the fuel now forced fuel into the primary fuel filters. I removed the bleed screw to the top of each filter and watched carefully. I could hear the fuel filling the canisters with an ever so soft whistling of air through the bleed screw hole. I had my spill container at the ready. Then first filter fuel and air bubbles came up through the bleed screw hole. I gently rapped the canister with a wrench and even more bubbles appeared until no more. I tightened the bleed screw finger tight and went to the next fuel filter and repeated the process. So far so good - no spilled fuel and the process worked. After checking to see if any more bubbles appeared, and they didn't I fully tightened the bleed screws.

For fuel to get to the secondary fuel filters I have to manually pump the fuel through the fuel pump located on the engine block. Of course the space is tight and the pump lever throw is minimal. For what seemed an eternity fuel finally spurted out of the bleed screw holes on the secondary filters. I made sure just like with the primary filters to tap the canisters and bleed any air out. Again, so far so good.

Finally I had to manually pump the fuel pump and open up the bleed screws on the injection pump. First the forward one and then the aft one. Again when only fuel was squirted out with no bubbles I tightened the screw and moved on. Now the real test - will it start?

I extricated myself from the engine room. And I use the word 'extricated' because after kneeling and working for over an hour on various filters I wasn't moving too fast. It was painful trying to kneel backwards, and slide myself out, but I did. The fresh air felt wonderful - not only cooling, but refreshingly without the diesel smell. I then turned the key and hit the start button. She's cranking over..., wait..., there's some firing..., and "verrrooom" the engine kicks to life. Oh my the relief that I felt. I did not want to climb back down and go through the bleed process. I let it run for a few minutes, even revving it up to see if any air bubbles would stop the engine. Better now than when I am just leaving the dock or getting underway.

I looked at the saloon clock and noticed that almost 3 hours had passed, but the dreaded fuel filter chore was OVER! I did crawl back into the engine room and thoroughly checked for leaks - none found. It is now "beer-thirty" and time to enjoy what I have accomplished and relax.