Fuel filter replacement on 300 Cummins ISB

Just past the rear axle on the passenger side I bet you will find a small in line filter.
I think I called Freightliner with my vin # they gave me the part # on my 03 with a 300 cummins ( Rail Filter RAI 025RAC10 ) after I called Freightliner went to NAPA an picked one up so I knew what I was looking for. Very little fuel leaked out when filter was removed. Remember free advice is worth just what you paid for it.

Vetia, You said you only have one filter on your freightliner chassis, I bet if you looked on top of the rear axle on the passenger side you will find a filter about the size of a can of hairspray. P. S. it needs changing now

dogvetia wrote:
I have the 300 ISB albeit on an older (2004 journey) freighliner. It has only one filter --with the electric and water separator all in one. I have had a freightliner mechanic look to make sure I was not missing the second filter but it is not there. I have 90,000 miles and 9 or 10 filter changes under our belt with no issues . the procedure described is what I use--ie fill the filter with fuel and then install. lots better to have it start rather than trust the electric fuel pump to fill the filter once installed.

Thanks a bunch. Pretty sure I only have the one filter as well. I've tried searching YouTube and haven't found anything.

I have the 300 ISB albeit on an older (2004 journey) freighliner. It has only one filter --with the electric and water separator all in one. I have had a freightliner mechanic look to make sure I was not missing the second filter but it is not there. I have 90,000 miles and 9 or 10 filter changes under our belt with no issues . the procedure described is what I use--ie fill the filter with fuel and then install. lots better to have it start rather than trust the electric fuel pump to fill the filter once installed.

Good point. I've been carrying this one and will get another. It is the water separator as well.

Thanks again.

Kaven

"gsf35099".....As I said, some only have one. I've only changed filters on my two ISL's and they use two filters. Hopefully, someone will come along with a coach like yours and know where everything is at.

Don't forget to carry a spare with you at all times. I rotate a new one into the spare position every time I do my filters.

YouTube is your friend. Have you checked to see if someone has posted instructions?

Thanks, Don. This really helps. I am on a Freightliner and have the new filter for the rear one. My Cummins owner manual only refers to one fuel filter. It provides the Cummins part number & Fleetguard part number. Doesn't say anything about a second filter.
If there is a second filter, is it easy to see from top of the engine looking under the bed?

Thanks again.

I'll take a shot at this....to start, every motor home brand is different, so your exact procedure is difficult to discuss without seeing your coach. Most coaches have two filters, a primary and a smaller secondary. Some have just one.

If you're on a Freightliner chassis with a rear radiator, you most likely have one filter under the bed and another at the rear of the coach. Either way, the primary filter GENERALLY has a fuel drain and electrical connection.

If this is the first filter change, the filter may take some work to break it loose. Unplug the electrical connection and drain the filter if convenient, but not necessary. Remove the filter and MAKE sure that all O-rings come off with the old filter.

The Cummins engines are designed to have the fuel filters installed dry. Once the filter is installed, you cycle the ignition switch on for a few seconds while you here the fuel pump run. You do this several times. With that said, I've found that this often doesn't work. (Someone will come along and say it works great, but that doesn't help when you can't restart your coach and start to panic.)

I like to prefill my filters. Fuel enters the filter from the outer edges and exits via the large hole in the center. You always fill the filter from the outer edges so the fuel you introduce during the filter change is filtered. Many use a pvc threaded plug to plug the center hole. I just clean my hands and insert my fat thumb while adding diesel fuel.

Reinstall the filter, making sure you reinstall the new O-ring(s) that came with the filter and reconnect the electrical connection. No need to get a gorilla to install the filter or use a strap wrench. I tighten mine with my hands until snug.

Move to the next filter. Same procedure. Once done, fire it up and check for leaks.

Here is a procedure I just posted yesterday for changing the filters on my new Dutch Star.

Dutch Star filter change