Community Forums

DieselPig · 08-06-2022, 02:53 PM

Hello all,
Fairly new owner (Feb 2022) of a 2003 Fleetwood Discovery 39J, approx 42K mi. CAT 3126 engine.

I have been researching as much as possible on my coach for critical maintenence points and preventative items.

The service history of my coach is not 100% airtight so naturally I have ran into a lot of questions.

Im not entirely sure the last time the fuel filter / water seperator was changed. I havent experienced any issues with the coach running so far. However I have noticed at the bottom of the clear bowl debris has seemed to settle. (Photo attached)

I am planning a cross country trip quite soon and wanted to know what I can do to address this if need be.

Also when I have opened the drain valve at the bottom the liquid appears to be mostly diesel fuel, however it looks like air bubbles rush upward through the fuel to the top of the filter? Is that normal?

Thanks in advance for the help.

wolfe10 · 08-06-2022, 03:00 PM

Assume you opened the fuel filter drain with the engine off (right way to do it).

Whether air enters the fuel filter under that condition is not particularly telling. If level of fuel in tank is lower, opening the drain will allow air in.

If level of fuel in the tank is higher, fuel will run out of the drain.

Verify that you do only have ONE fuel filter.

If only one, absolutely use a Caterpillar spec 2 micron filter. And, if this is the only fuel filter it will clog up much quicker than if you have a 10-30 micron primary and the 2 micron secondary fuel filter.

DieselPig · 08-06-2022, 03:11 PM

Thanks for the quick response, yes I have only opened the valve with the engine off, currently has about half tank of fuel in the coach.

I have verified by visual inspection and extensive research that my particular coach only has 1 fuel filter. My impression is this is all the more reason to make sure this filter is replaced routinely and at the correct micron rating.

I believe the current filter is Alliance brand, not entirely sure of the micron rating as it came on the coach. But I will be looking into that next.

Is there a way to swap the filter /bowl without the potential for fuel system air lock issues?

Thanks again.

wolfe10 · 08-06-2022, 03:26 PM

If a Caterpillar fuel filter will fit that housing, USE IT.

Excellent quality and not much more than the other brands.

And, absolutely with your engine, use a 2 micron filter and DO change it frequently.

If you are going to keep the coach, another option is to ADD a Caterpillar secondary fuel filter with manual primer pump and put a 10-30 micron element in the primary.

Should be able to find one used or new-- haven't changed in decades.

DieselPig · 08-06-2022, 05:23 PM

Okay thank you much for the feedback! I had started to research installing a primary pump on the system and ultimately I believe I will do that. Seems clean fuel is imperative with these HEUI pumps.

I also started reading on the HEUI supply line update as Im still running the braided line.

Lots to learn on these coaches, what a hobby! Ha!

And I thought installing a new cam shaft , oil pump and rocker arms was a big deal on a 05 Corvette when I did it last year. LOL.

DieselPig · 08-08-2022, 03:59 PM

Quote:

Originally Posted by DieselPig

Okay thank you much for the feedback! I had started to research installing a primary pump on the system and ultimately I believe I will do that.."

Sorry I meant to say , "I had started to reasearch adding secondary fuel filter with a manual priming pump"

Thank you again for the info everyone.

bpu699 · 08-08-2022, 05:27 PM

How often does the secondary filter get clogged? I see lots of posts about the primary filter clogging… never the secondary…

DieselPig · 08-10-2022, 09:59 AM

Quote:

Originally Posted by bpu699

How often does the secondary filter get clogged? I see lots of posts about the primary filter clogging… never the secondary…

Im unsure about that. I only have one fuel filter on my coach. Luckily the previous owner already had a new spare and a new spare bowl. Going to swap them at the next fuel fillup more than likely.

the sights · 08-11-2022, 03:54 PM

Quote:

Originally Posted by bpu699

How often does the secondary filter get clogged? I see lots of posts about the primary filter clogging… never the secondary…

Well how do I answer this other then I change mine ever year 3,000 or 4,000 miles don't matter.
We put on 7,400 this year coast to coast and changed it 1/2 way on our trip so I have no idea when it would plug nor do I want to know.
We had 0 CEL or any problems or our long trip I believe its because of total preventive maintenance practices.

wolfe10 · 08-11-2022, 04:04 PM

Only your Quiji board can predict that!

Are the particles/contaminants large (will be caught by the primary/course filter) or fine (only caught by the secondary/fine filter element).

Reality is change them both-- or consult your Ouiji board!

Single filter. With your engine it is a two micron filter element. Yup, It WILL clog up first/quickly with any fuel contaminants.

astrnmrtom · 08-11-2022, 04:31 PM

More important than clean fuel for the HEUI is clean oil. Don't follow Cat's 10,000=15,000 mile interval. Change it sooner 5000-7500 miles, and your HEUI will thank you for it. I worked in a shop that was next door to our transportation department. When I got my rig I asked the head mechanic if they had problems with HEUI pumps failing in their buses. His answer was "Nope, none." Those buses were run on a severe service schedule meaning oil was changed more frequently. I do a similar schedule - 5000 miles is my target. I do the changes myself and since I'm not always in a campground that allows it, the actual interval may drift a bit from the target.

A little sediment isn't unusual, the clear part of the filter and the drain is for monitoring for water. Water will settle into the bottom of the clear bowl making it easy to drain out.

The fact that you are concerned and are asking questions means you are ahead of the curve. Simple periodic maintenance will go a long way toward your engine enjoying a long and happy life.

FIRE UP · 08-29-2022, 10:28 PM

Quote:

Originally Posted by DieselPig

Hello all,
Fairly new owner (Feb 2022) of a 2003 Fleetwood Discovery 39J, approx 42K mi. CAT 3126 engine.

I have been researching as much as possible on my coach for critical maintenence points and preventative items.

The service history of my coach is not 100% airtight so naturally I have ran into a lot of questions.

Im not entirely sure the last time the fuel filter / water seperator was changed. I havent experienced any issues with the coach running so far. However I have noticed at the bottom of the clear bowl debris has seemed to settle. (Photo attached)

I am planning a cross country trip quite soon and wanted to know what I can do to address this if need be.

Also when I have opened the drain valve at the bottom the liquid appears to be mostly diesel fuel, however it looks like air bubbles rush upward through the fuel to the top of the filter? Is that normal?

Thanks in advance for the help.

Well Sir,
We have an '04 Itasca Horizon 36GD with the CAT C-7 330HP and it too has only ONE fuel filter with a water bowl on the bottom. As Brett stated, if your fuel level is lower than the height of the filter housing when you are changing your filter, you're in for a BIG SURPRISE!!!! It's a long story but I won't go into it now. Suffice to say, I couldn't start our rig for a full 24 hours due to following the instructions in the CAT engine book for fuel filter changing.

I ended up installing shut-off valves on both sides of the filter housing. Ever since that valve install, I've had ZERO problems changing the one and only filter. And speaking of that, we now have 103,000 miles on this well performing C-7 and I have used both WIX and CARQUEST (both the same filter but slightly different part numbers) for multiple fuel filter changes and not one hiccup with that engine. AS for the debris in the bottom of your water bowl, well, not really normal but, that's what it's there for, to collect unwanted contaminates so, your filter did its job.

If you want to install a second filter, have at it. But, myself and a few thousand other Freightliner/CAT equipped coaches have had great success with only ONE fuel filter. Freightliner and CAT had some words quite a while ago about whether or not to run two filters and at that time, the bean counters won so, for a short while, Freightliner diesel chassis coaches were equipped with a SINGLE fuel filter. And guess what, it worked!!!!!!!!!

The HEUI pump on these CAT engines is not cheap to replace. It likes CLEAN OIL so, I go waaaaaaay beyond CAT's recommendation for oil/fuel filter change intervals and do mine twice a year. OIL and FILTERS are cheap compared to that HEUI and damaged related components (normally a damaged HEUI takes out at least one or two injectors with it). So changing oil more frequently is no big deal with me. Good luck with your new coach. I myself am quite satisfied with my C-7 CAT.
Scott

DieselPig · 02-26-2023, 08:57 AM

Sorry I just saw this and thank you for the info, very helpful. Much appreciated!

Ted DuPuis · 02-27-2023, 07:31 AM

Interesting, I didn't know that Cat ever made a 3126 with only the water separator filter. All the ones I've seen have two - one on the engine, and then the water separator further away from the engine. I generally change them at around the same time as I change the oil (which I normally do at 5-6k miles). So far, my HEUI system and injectors have been good to me (knock on wood).

The debris in the bottom tells me that the filter/separator is doing its job. If you don't know when it was changed, change it. Try to find the appropriate Cat part number and use that, you should be able to find a cross reference.

Sometimes, Cat makes both a standard and an "Ultra High Efficiency" filter. If you can find the latter, use it. That may take more research.