Priming the Fuel Filters Question

[56Nomad]

Can one prime either the primary or secondary filter
by opening up the air bleed valve on the the respective
filter head and putting a small amount of air pressure
in the fuel filler opening.

I notice that the fuel line from the fuel tank first passes thru
the EDU box before it enters the OEM fuel filter head. My
question is...can we push fuel thru the EDU (obviously, with the
engine off) without causing any problems within the EDU
or other parts of our fuel system?

When I had the Racor 660 mounted on the frame (serving
as the primary filter) I used a bicycle pump on a valve stem
running thru an old gas cap. It worked like a charm to
prime the filter and bowl. In that case, the fuel went directly
from the tank to the frame mounted filter assembly. I figured
too much pressure from an air hose would be excessive.

To prime JK's Mega filter, NWDmax reported it took 217 pumps
on the primer. Could a little pressure added in the fuel tank be
an easier way to prime the filters under the hood??

[ 03-16-2003: Message edited by: 56Nomad ]</p>

[dmaxalliTech]

56, I did read in another thread that JK mentioned priming by pressurizing tank, might want to get more details from him on that, bicycle pump sounds like a great idea. why couldnt you fill your mega filter with clean fuel before installing? sure would take the work out of priming if some fuel was already there. I dont think you would damage the FICM, the fuel circulates through the base plate of the unit. doesnt actually go through it.

[FirstDiesel]

Wouldn't prefilling the filter defeat the purpose of installing it?? The fuel you put in wouldn't be filtered and how are you going to get fuel clean enough to fill it??

[mdrag]

I intended to count the number of pumps when I did this install...but one of the kids distracted me at about 105. Just when you think nuttin' is going to happen, diesel comes gushing out :eek:

I'd bet that Baldwin MegaFilter in Kennedy's kit takes dern near 1/2 gal to fill... :D

[TraceF]

If it's installed as a pre-oem filter you could pre-fill it. Then run the truck at idle until it stalls and bleed the air burp. The system will be full. This is how I bleed the air that gets in the system when I change the (soon to be upgraded) Stanadyne. I don't pre-fill it because it has a primer pump but air still gets in when you change it.

[Somis Duramax]

When I installed John's filter I opened bleeder on the Mega filter and put an air hose in the filler neck with a rag around it. Gave it a couple of quick blasts and hit the primer 15-20 times and got fuel out of bleeder. Started the truck which ran for about 10 seconds and died, pumped up primer again and started it right up.

[Kennedy]

The blow gun/rag method is much safer. It isn't necessary to put any REAL pressure in the tank, just a bit. I use the primer pump myself...

[george morrison]

As is common practice, one fills an oil filter to prevent momentary loss of oil pressure, etc. However, in a fuel filter, pre-filling the filter with diesel fuel is, in a word, *NO*, NEVER, DO NOT!!! If we pre-fill a fuel filter, we are going to very likely end up with a gazillion particles in the 'clean' side of the filter. This is what the primer pump or JK's procedure is for; fuel is introduced via the pump into the 'dirty side' and then flows through the filter, ensuring only clean fuel is introduced into the system. Keep the wrap on that filter until the last minute, put a light lubricant on the seal and install. Yes, almost surgical level cleanliness.. Then pump away to fill the filters.
Using this procedure will ensure minimized contamination of the fuel filter fuel system. CAT and others have no installed spring loaded ports to prevent pre-filling on some of their fuel filters, they feel so strongly about the potential damage that can occur with pre-filling the fuel filter. There have been many reported cases of immediate fuel system/injector damage occuring immediately after changing fuel filters. In most every case manufacturers found FOD contamination from 'pre-fill' the culprit.
George Morrison, STLE CLS

[ 03-17-2003: Message edited by: george morrison ]</p>

[56Nomad]

John,

I don't know what you mean that the "blow gun/rag method
is much safer" than my humble bicycle tire pump. The advantage
of my gas cap w/valve stem contraption is that the amount of air
pressure applied is very measured and controled.

Also, should I be on the back roads and one of my filters clogs up...........
I certainly won't have my compressor with me, but the bike pump is
stored under my back seat.

One other problem--- I never seem to have any
clean rags in my garage.

Thanks for your reply, as we now have more than a couple of ways
to prime the system. :D

[ 03-17-2003: Message edited by: 56Nomad ]</p>

[Kennedy]

I didn't catch the bike pump thing, but it should work. In the wrong hands however, the fuel tank inflation cap can be dangerous...

As for the number of pumps, it is definitely over 100, but if one is too fast about it, the primer does not fully refill, and sometimes there are wasted strokes.

[a bear]

Thats what she said ! :eek:

[dmaxalliTech]

I guess I didnt think about the position of the filter, or about my comment, or about the side effects, or about how stupid that really does sound to fill it with "clean" fuel, the same fuel we are cleaning with the filter... If any body is looing for me, I will be in the corner with my nose on the wall, and some soap inmy mouth smile.gif

[Big O]

I am sure someone will say it is a NO-NO, but my brother has owned big rigs for 25 years and when he changes filters, he fills them with CLEAN automatic transmission fluid, straight from the can. Starts right up and has NEVER caused a problem with those 'super-expense' diesels. I have heard of many other truckers using the same method. When I used to change my own filters on my old F*rd, I always used that method. :D

[DURA-MAX3]

I to have used this transmission fluid trick, but not on my personnal vehicle. Our mechanics here in the shop do this on a regular basis. Trans fluid is a cleaner for the injectors they tell me. I know that we don't have any engine trouble from them doing this...

[george morrison]

The last "clean" ATF I checked had a 21/19/17 ISO cleanliness.. i.e. it was very dirty and not acceptable relative to our fuel system cleanliness requirements.
And yes, I am very familiar with the practice of pre-filling filters with everything from ATF to various fuel additives and of course, diesel fuel. Back when Big Cam IV's and mechanical injected Caterpillars were using 3,000 psi injector pressures and exchange injectors were $28, these practices were not too harmful.
However, with today's 30,000+ system pressures pre-filling with a 21/19/17 dirt level ATF or any fluid would create the immediate possibility of system damage. Caterpillar, for one, has a 10 page tech topic covering this exact subject. CAT field mechanics had been 'pre-filling' bulldozer fuel filters for years. This was a very tough habit for CAT mechanics to break; so much so that on many filters CAT/Baldwin/Fleetguard have installed covers to prevent pre-fill. (and yes, creative Murphy's have even tried to bend them open, damaging the filter with resulting fuel system damage).
So, with today's electronic, ultra high pressure systems, pre-filling fuel filters is not only not recommended but absolutely forbidden by all current diesel engine manufacturers.
George Morrison, STLE CLS

[svpdiesel]

George, I think the problem is that it's difficult to imagine how small a 2 micron particle is, and how many of them there could be in a "fresh" can of ATF, or anything else. To put it in perspective, a human hair, TWO THOUSANDTHS of an inch in diameter (.002") is 50 microns in diameter! A micron is .00003937 inches. In area, you could fit 1,963 sq microns on the end of that hair... Lotta microns.
So, even though fresh ATF LOOKS clean it is NOT filtered well enough to eliminate this small of a particle.
I know that some of the tolerances in our DMAX injection systems are measured as small as 5 microns, so anything in that size range will damage the surfaces. The old mechanical systems had tolerances measured in thousandths of an inch, (5 times as large as 5 microns), and were not as sensitive to this tiny little stuff you can't even see... In our case, what we can't see, WILL hurt us.
Hope this helps visualize just how small we are working with.

[george morrison]

Thanks so much for the micron referencing. Since I deal with ISO cleanliness and microns each day I lose perspective. That is one reason I translated the ISO cleanliness ratings into particles per gallon to yield some relevance to particles per gallon that our systems are seeing, processing. As I mentioned previously, here we are setting targets for cleanliness that used to be used as standards for aviation jet fuel! Yet that is exactly where we need to be to ensure maximum fuel system and injector life.
George

[YZF1R]

I totally agree with George and John. Never pre-fill the filter. I had a 1693 Cat in one of my trucks (Man, what an engine!), and I was strictly told by Cat to: "ALWAYS use the primer. That's what it's there for. As long as only clean fuel goes into the pump, you'll never have any problems." You don't want any problems with those pumps either as they are very expensive to have worked on compared to a Cummins. In the old days, these were high pressure systems at 3,000lbs. compared to other mechanical injection systems. Never had that pump touched in 1.2 million miles. (Other than to give her another round of fuel. ;) ) Never had it rebuilt. My Cummins BC3 400 with the PT (Pressure/Time) fuel system would get the pump rebuilt about every year or two. One seal or onother would start to suck air for whatever reason. One time was when we went to low sulfer fuel. You pump people know what happened to seals going from regular to low sulfer.

Guess I better stop going down memory lane now.

Bottom line: Please use the primer.

Steve

[Big O]

George,
Boy it sure is nice to have the knowledge of experts at hand, to keep uninformed people like me from messing up. Keep up the good work!