Fuel supply line disintegration

[Fred Brooks]

               Greetings Friends,

        I have been following the thread under "Tools to carry" and it has gone down a rabbit trail concerning fuel filters and the supply hoses from various parts of the fuel system. After talking to Dave Atherton at the Quartzite rally, we decided to inspect the fuel system on my coach.
       My coach is a great example of everything Dave is trying to convey to everyone on the Forum. Careful inspection of the screen canister on my original Winn fuel reveals chunks of rubber that has come from the "Hydraulic hose" that SMC installed from the fuel tank to the primary fuel filter. That not bad enough, but they also installed a "hydraulic hose" from the output of the primary filter to the Pump on the engine. That hose is leaking from the inside out thru the outer rubber lining of the hose. Dave has put together his recommended "FIX" for this impending situation that will eventually take out the pump from starvation and could hurt your injectors.
         Kudos to Dave for the heads up......Regards, Fred

[john brunson]

As always, I seem to remain dazed and confused!  my understanding from Dave was that the secondary fuel filter would protect the injectors, pumps, etc and various other Caterpillar components.  Is this the "Flow"??

FUEL TANK ====> PRIMARY FILTER =====>PUMP ====> SECONDARY FILTER===> ENGINE COMPONENTS

Main question - is the above accurate? and is the last hose on the diagram susceptible to the described decay?

[Dick Simonis]

Fred, thanks for the heads up.  I went out to look at mine but can not tell if it's hydraulic hose or a cat fuel hose since they look very similar to an untrained eye.  Guess I need to scrape off some yellow paint and look for any markings.

https://parts.cat.com/en/catcorp/high-temperature-fuel-hose-assembly#facet:&productBeginIndex:0&orderBy:&pageView:grid&minPrice:&maxPrice:&pageSize:&

Dick

[Dave Atherton]

Gentleman, yes we do have a problem and would suggest not take this lightly.looking at Fred's
picture seeing break down of hydraulic hose contained within the primary fuel filter via: ( fuel tank to
primary fuel filter on suction side ) we can live with this and change primary out fuel filter. The
fuel exit from primary fuel filter to fuel transfer pump is the main concern because this is hydraulic
hose also. Problem: hydraulic hose breakdown after primary fuel filter and plugging suction
side enters to fuel transfer pump. This hydraulic hose needs to be replaced with a plastic fuel
hose ( primary fuel filter to fuel transfer pump 4 feet long ). The aftermarket hydraulic hose
appears to stop at discharge or pressure fuel hose at fuel transfer pump and is back into the cat
OEM hose going to the 2 micron fuel secondary fuel filter. At present replacement of the hydraulic
hose between primary fuel filter and fuel transfer pump will contain rubber within the fuel
filters. Suction fitting on fuel transfer pump plugged with rubber will cause low power and reduce
diesel fuel keep injectors cool from diesel fuel. What does this mean ahead, failure of the fuel
transfer pump and injector failure. Cost for 4 feet of plastic hose and fittings $ 30.00. This info.
will protect your engine fuel system and contain rubber from hydraulic hose to front fuel tank.
Ahead I would suggest replacement of suction fuel hose from fuel tank to primary fuel filter.
Note: I have posted This problem before and it affects many motorhomes but again this problem
will cause failure and get very pricy. Dave Atherton Retired Cat mechanic

[Dave Atherton]

Gentleman, and thanks Dick providing link on Cat fuel hose. What is needed for this
repair, 4 feet of 1/2 I.D. Hose with ( 2 -8 female JIC swivel ends ). Looking at Link on
pre made Cat fuel hose before buying make sure you have the correct hose fitting that
will be crimped. Most Cat pre made hose has the Cat flat face swivel fitting as shown
and will not match to the JIC aftermarket fitting present on motorhomes in question.
A person can get a hose made at Cat dealer if not. What you need to ask for, you want
4 feet of 1/2 inch pilot system plastic hose with ( 2 ) -8  JIC female swivel ends crimped
in place fittings. The hose may be metric but the -8  JIC female swivel fittings will connect
To motorhome. This plastic pilot system hose has a burst pressure of 450 psi and will
not break down by fuel. Dave Atherton Retied Cat mechanic

[Fred Brooks]

      Hi Guys,

    Dave and me are sitting here discussing the fuel hose problem. Enclosed you will find another photo of a C-12 that has the same issue along with air in the fuel system.

[Dave Atherton]

Update fuel problem Quartzsite Rally, lnspection of motorhomes present and found
several with aftermarket installed hydraulic hose used in fuel system as the main fuel
supply. Found total of 5 motorhomes showing break down of rubber hydraulic hose
in plastic inspection screen. Found 7 motorhomes with hydraulic hose leaking from
the primary fuel filter to the fuel transfer pump ( note: install of clear line for air leak
test shows air is also present on suction fuel side from fuel tank past primary fuel
Filter. As my earlier post install of a 4 foot plastic hose between the primer fuel filter
and fuel transfer pump will contain debris within the primary and secondary fuels.
Dave Atherton Retired Cat Mechanic

[Lee Welbanks]

Dave,

Is there certain coaches and years that they used the hydro hose?

[Lawrence Tarnoff]

Also ... what about Cummins?

Larry

[Dick Simonis]

One point of clarification needed.  When looking at the hose how can one tell if it's a hydraulic service hose or a Cat fuel hose??

[Dave Atherton]

Hi Guys, first question use of hydraulic hose for fuel system. Near as I can tell going
back to 1996 and 2003. So far than mfg started to use plastic fuel line. What I can tell
so far aftermarket Racor filter prime setup and aftermarket primary fuel filter setup.
What we have found hydraulic hose was used starting from fuel tank to primary fuel
filter than exit primary filter to fuel transfer pump than will go back to Cat OEM fuel
hose to the secondary 2 micron fuel filter. At present all that is required, replacement
of hydraulic hose ( read my above post ) between primary fuel filter and fuel transfer
Pump. This ( 1 ) hose replacement will contain all debris within fuel filters.

Question Cat fuel pre made fuel hose and what a Cat fitting and a JIC fitting. ( Cat fitting )
female swivel fitting has a flat face. Cat male fitting has a flat face with groove for a
o-ring that makes the seal when tightened.  JIC female swivel has a  37 degree bevel
inside of hex swivel.  JIC male has a 37 degree bevel before the threads to tighten into
female swivel. In our fuel problem aftermarket JIC fittings were used is which is used
Industry wide and a very good coupling, but not used very much with Cat equipment.

Question number 3, Cummins Fuel Systems. The Cummins fuel system uses a cloth covered
plastic fuel line and there fuel system is different than the cat system and has not been
changed with aftermarket setup. Last, the type of hose connectors for newer Cat with plastic
fuel hose another story they have a o-ring that is problems because they cannot seal
after o-ring gets hard.  Thanks for the questions hope this answers your thoughts.
Dave Atherton Retired Cat Mechanic

[Dave Atherton]

Fuel Supply line, need to correct above post. We feel the use of hydraulic hose started around
1996 and ran through 2003 than looks like change over to plastic fuel line with o-ring fitting.
Another problem which Mfg starting using connector with o-ring snap in place style. What has
happened with this o-ring setup ( will leak air into fuel system when o-ring gets hard over time ).
Dave Atherton Retired Cat Mechanic

[Joel Weiss]

I'm not doubting Dave's expertise in this area, but I did a bit of Googling and it does appear that there are plenty of hydraulic hoses the manufacturers of which specify that they can be used as diesel fuel lines.  As an example, here's a link to one manufacturer's webpage: http://www.parker.com/portal/site/PARKER/menuitem.7100150cebe5bbc2d6806710237ad1ca?vgnextcatid=4593890&vgnextcat=RUBBER+HYDRAULIC+HOSE&vgnextoid=f5c9b5bbec622110VgnVCM10000032a71dacRCRD&vgnextfmt=EN  As far as I can tell the problem is not simply that a hydraulic hose was used in place of a fuel hose, but, rather, that a specific hydraulic hose was used that wasn't rated for that use. 

This leads me to question as to whether ALL Beaver products during the 96-03 timeframe have an improperly spec'd hose or only those on which a specific hose brand/type was used.  Knowing the problems that SMC had with the hydraulic hoses that served the main slideout in the ~1999-2001 time period, the question arises as to how many different suppliers and types of hose may have been in use.  The filter on my MH has none of the debris shown in the above-posted photos, nor am I seeing fuel seepage through the walls of the hose.  It doesn't mean that it can't still occur only that it hasn't yet.

Maybe Dave can clarify this issue.

[Steve Huber Co-Admin]

Joel,
I didn't access the complete paper but the abstract seems to indicate bio-diesel has an impact on the rubber in fuel hoses. Without reading article it is not clear if this could cause the rubber to break loose from hose as is indicated from Fred's photos however.
http://www.sciencedirect.com/science/article/pii/S0360544214002217
Steve

[Joel Weiss]

Steve:

I agree that this could be a concern, but, of course, the paper is about nitrile rubber fuel lines, not hydraulic hoses. 

Joel