Change final fuel filter - Cat 3126e - with primer pump

[dansawyer]

This may be a duplicate, I looked but could not find the specific topic. The RV is a 2002 National Tradewinds on a Spartan chassis with a Cat 3126E. I am planning on changing the final fuel filter.

I have found the filters. There are two, the first is a water separator and the second is a standard Cat 2 micron filter with a primer pump. I assume removal and installing are the standard process. I will coat the rubber gasket with a light coat of oil.

Is this correct?

Finally, how is the primer operated? Does the knob untwist before operation? What is the approxamate length of a stroke? How do I know if it working? How will I know when the filter is full?

Currently the diesel starts are an 'A'. It is consistant, without fail. The lowest was about 20 degrees, I was impressed. What did come out of the post search was stories of vehicles that did not start after a change. I would like to make this as fail safe as possible.

Thanks Dan

[JNSNWT]

Prefill the new filter with fresh clean fuel. This will also act as a lubricant for the rubber seal
As you stroke the hand pump plunger it will become stiffer and harder to push.

[Skip426]

The primer pump has a knurled cap, that the shaft runs through ; that needs to be undone to allow the knob to be moved .

[wolfe10]

Originally Posted by JNSNWT

Prefill the new filter with fresh clean fuel. This will also act as a lubricant for the rubber seal
As you stroke the hand pump plunger it will become stiffer and harder to push.

This is NOT Caterpillar's recommendation.


Yes, lube the new Caterpillar 2 micron fuel filter Oring/gasket with diesel or motor oil.


Remove the old one. Verify that the Orings/gaskets came off with it or remove them.


Install the filter dry and use the primer pump to prime.


To use the pump, unscrew the knurl nut (counter clockwise). Pump smoothly in and out. It will go from easy to pump (air) to very hard in a couple of strokes. Note, it may take quite a number of strokes to reach this easy/hard junction.


It becomes hard to pump because fuel is non-compressible and you will be pumping against the check valve in the fuel return line in the back of the head.


Then push in the primer plunger and screw it clockwise to lock the plunger in place.



Been there, done that many, many times.

[the sights]

For the last 16 years I have installed my CAT fuel filter and water/fuel/filter dry then pump the primer pump about 60 to 70 strokes its only a 2 or 3 inch stroke and it will be more difficult to push/pull as the system becomes full of fuel. then I start it up never fail. Just look on the CAT filter it states not to pre-fill.

[dansawyer]

Thank you. That is what I was looking for. I am a new owner and the PO did a good job of most things, however there are a few gaps. I want to make sure we do not spend a long night on the side of the road.

[ftodaro]

I usually do the water separator first, I am a prefill guy just make sure you fill through the small holes. The I start it and then I do the filter on the motor. My point weather you use the primer or pre fill do one at a time and start in between.

[dansawyer]

Thank you all. Quick update:
We are on a trip, currently 3800 miles on a 5000 mile journey. I believe we picked up a moderately bad fuel load in Montrose CO, about 50 gal. We then drove 200 miles over Monarch Pass to Canon City. At the very end of the leg while climbing 2000 feet in 10 miles on CO 9 North I began to notice a stumble in power on the longer steeper grades.

The tank now reads about half full. Now What?

The first, water seperator, filter is a 533005 and I have one on the way for delivery Monday at NAPA in Canyon City. I have 3 spares for the final in the basement.

Do I try to drive another 100 miles before changing?

I certainly plan to try to order 2 more 533005 from NAPA.

The return trip will take us back over Monarch and then back through Montrose to Grand Junction and Green River. I will take the tank as low as I can before refilling. At half full I have on the order of 400 miles before it gets near empty. Worse case that would imply a filter set change now, a second in Montrose, and a third when refilling in Grand Junction. That seems excessive. Am I over planning.
Thank you all again. Dan

[dansawyer]

One final question: How much fuel will typically drain from the fittings when I remove the filters? Is this a gallon on the ground and fuel up to my armpits while changing or is it fairly clean operation?

[wolfe10]

Originally Posted by dansawyer

One final question: How much fuel will typically drain from the fittings when I remove the filters? Is this a gallon on the ground and fuel up to my armpits while changing or is it fairly clean operation?

Could be none (a BAD THING) or alot.


It depends on the level of fuel in the tank compared with the level of the filter head. If fuel in tank is higher, fuel will run out until level with filter head-- can be many, many gallons.


If level of filter head is higher than level of fuel in tank, fuel will drain back to the tank, leaving you with 25'+ of AIR in the fuel line.


The real/correct solution is to add a BALL VALVE to the inlet side of the primary fuel filter. Close it and no fuel will drain out and no air to purge from the fuel lines.


In the mean time, have the new filter absolutely ready to install. If clear bowl on it, buy an extra and have it assembled, oil on gasket/O ring and ready to go. Be sure to check that the old gasket/O ring comes off with the oil filter.


And, no one can tell you have many miles you can go on a filter. What does the fuel look like in the clear bowl OR if you drain some into a clear glass jar from the primary fuel filter? Better to err on the side of changing too often as you can damage fuel injection components if starved for fuel.

[bpu699]

I’m doing the same in a couple weeks. Any way to screw this up?

My rv is on a slight incline, front end down.

I’m worried that it’s going to take 1000’s of pumps from the primer to get fuel back into it if the fuel went back into the tank…?

Concern, or not so much?

[dansawyer]

Quick update:

For someone reading this thread, I removed the first water separator filter. The tank was about 1/2 filled and roughly level. When I removed the filter about 1 to 2 ounces of fuel leak out. This was easy to manage. I replaced the filter with the same model number that the PO had used.

I tried to fill the first filter with the primer on the final, second filter. This did not appear to work, the pump was essential very stiff. Based on this I tried to simply start the engine. This worked, there was 30 seconds to a minute of rough engine before it smoothed out. The take away is if the fuel spillage is small it may be practical to use a running engine to refill the first filter.

(I have not replaced the final filter yet in this setup. If someone has please post their experience.)

Dan

[bpu699]

Does the system self bleed any air in the system? So no need to attempt to bleed like with older diesels?

I always heard horror stories the old diesels were impossible to start if you lost prime…

[bpu699]

Well, just did this. Did the primary fuel filter (easily accessible), didn't do the secondary.

RV with full tank of gas, on slight decline, front end down.

I think the full tank of gas is key, as the fuel in the lines didnt run back to the tank...

Taking off the fuel filter was an absolute bear. The bracket was bending with the strap wrench, but it wouldnt come off.

Had to take the fuel lines off, take the entire base and put it in a vice, and unscrew it. This was pretty easy to do, thankfully.

Filtered the fuel through a mesh screen used for autopainting. Tried to find a plug to cover the center hole, and couldnt find anything that fit.

Finally took a round magnet I had, put it over the hole, and this worked GREAT!

Prefilled via the outer holes, started it right up, ran fine.

Unless I'm misunderstanding this, contamination really isnt an issue, as the fuel still has to flow through the second filter. Is this not the case???

In fact, the picture ON THE FUEL FILTER shows the filter being filled through the middle hole! (Donaldson filter)

Now, changing the 2nd filter worries me. That is the final filter, and you cant contaminate it. Plan to put it on dry and use the primer pump.

Any thoughts on the magnet trick? Worked really well I put the magnet in a ziploc back so it was easy to pull off...