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Friday, April 22, 2011

Changing the Diesel Engine Fuel/Water Separator Filter

After driving the Journey about 1200 miles these past two weeks, I finally had a little down time to catch up on some maintenance.  Diesel Pusher (DP) motorhomes require a large amount of preventative maintenance and I do most of it myself.  I don't always have the time to get everything done, so I spread it out and do it in small bunches.

I had a minor drip from the corner of my recently installed windshield, so I removed all the molding in that area and resealed it with some heavy duty silicone.  Also, I had a couple of loose screws on my awning where it attaches to the roof, so I got some longer and thicker screws and tightened them down and sealed them with Dicor caulk.

I have not had a chance to give the Journey a good washing since last fall, so it got a bath using a heavy dose of Blue Coral Wash and Wax, with another couple of ounces of Rainex Wash and Wax mixed in.  When it was done, the Journey gleamed.

My big items that were at the top of the list were changing the fuel/water separator filter (FWSF) and the air filter.  Today dawned cool and cloudy, so I started with the FWSF.  It is located on the rear of the Journey on a bracket in front of the radiator.

The yellow part is the filter and underneath is a plastic bowl that water and sediment can settle in.  On the bottom of the bowl is a petcock that opens to drain the filter.

Once the diesel fuel is drained, I used a strap wrench to remove the filter.

The sediment bowl is then removed from the filter.  It would be nice to have three hands at this point, but not being that equipped, I clamped the old filter in a vice.  Using two strap wrenches, the bowl twists off.

Using a clean rag, I wiped all the residual dirt from the bowl.

A new rubber gasket is installed on the bowl.

A very important step is to lubricate the gasket with some oil.

The the bowl is screwed on to the new filter.

No, I didn't clamp the new filter in the vice, I just rested it on the jaws and used the two strap wrenches to make sure the bowl was on tight.  While I was at it, I ensured the drain petcock was closed.

A new gasket is installed on the top end of the filter and again it gets lubricated with some oil.  The oil is important so the gasket slides into a seated position against the filter housing.  If the filter is installed with the gasket dry, there is a chance that it could tear and that would cause all kinds of trouble. 

I then reinstalled the FWSF back in place, I screwed it on as tight as I could by hand, then gave it a little additional twist with my strap wrench.

Now here is the the important part.  The filter is installed dry, Cat does not want you to pre-fill it with fuel.  The reason is the fuel you'd put in it would not be filtered and you don't want to get any tiny debris or dirt particles in the engine's injector pump or injectors.

You start the engine and rev it up as high as it will go and hold it there for several minutes.  This will cause enough suction from the injector pump to pull fuel from the tank into the filter and filter it at the same time.  After several minutes, the engine can be dropped to idle and let it run, while a visual check is done on the FWSF to ensure there is no leakage.

Everything came out well, so another task is crossed off my maintenance list.  Not a hard job, about an hour, it just requires a little muscle to twist things off and on.

  I had to put off the air filter change for another time because by the time I got the FWSF back on, it started pouring rain.  Just my luck.

Thanks for visiting and feel free to leave a comment.


  1. good for you for being able to do these 'jobs' on your own! about 'saving money'!!

  2. I am impressed that you do your maintenance yourself. That is one reason my husband and I decided NOT to full-time it. My husband is a great accountant, but no a good handy-man. Luckily my soon to be SIL, George ( of Laurie and George) is quite handy, so they should do fine.

  3. As nice as it is to save money by doing it yourself, what is even better is knowing that the maintenance has truly been done. Something you can't be certain of when hiring someone unless you can sit and watch them work. I wish I was so handy.

  4. Those windshield leaks are infamous in the Winnie world. Lots of folks are real unhappy with them over this issue.

    I recently had my first leak in five years. I had some other work done at a Winnie dealer, but they would not work on the windshield due to high probability of breaking the windshield when it is removed to sand rust away from the frame.

    But they would just put sealant down with no guarantee or liability. That has held up well in some heavy rains since then.

    I think the big trick is to not let a leak go on long enough to rust out the metal frame. This is apparently a big problem with Winnebago.

  5. Haha, my Mom posted. You are quite the handyman!

  6. VERY VERY good post! I love step by step how to posts on maintenance and upkeep on our RVs...

    You did a very good job explaining and why and showed wonderful pictures.

    We try to do all our own maintenance too, and it really does save a lot. More $$$ then for the ever-increasing fuel costs. Right?

    Karen and Steve
    (Our Blog) RVing: Small House... BIG Backyard

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