while servicing my 9u this weekend and complaining about the fuel sock
hassel , it crossed my mind to install an inline spin on filter like the one my cummins engine in my peterbilt uses on the main line before the transfer
pump since there is plenty of room.this is a rather easy install and would make service much easier and clean the fuel before it go's threw the trans pump.it would make for more frequent filter change and do away with pulling the hood and disasembling the fuel sock housing .by pre filling the spin on filter with fuel it would leave minimal air to bleed out the regular way .since
i have installed new fuel pumps and nozzels i would like to change fuel filters more often. cat did not give them away so i would like them to last a while.Has anyone done this already and if so were there any bugs in the system after install . thank you in advance if anyone lends there opinion.

Very common (and recommended) to install a pre-filter. There are several aftermarket versions available to choose from....Napa, Cummins, McMaster and others. Only trick is adapting to the Cat odd-ball thread at the transfer pump which is a ferrule type with 7/8-14 thread that will accept a jic "O" ring boss fitting and seems to seal ok even though it is not machined for it.

Here is a picture of a fitting that I made out of stainless. I built it so that it would seal on the same surface as the orginal fitting, then I used a flare fitting on the other end so I could use areoquip type hose, plus I hate pipe fittings.

There is a -12 37 degree flare on one side and the cat 7/8- 14, 30 degree flare on the other. A long bulk head could also be adopted by recutting the taper which is not stright BTW.

Hi CR,
I don't follow you on that last statement " the taper is not straight" can you elaborate?

The taper on cat fittings is not a true cone, there is actually two seperate angles in there that intersect in a splined curve. I found this out reverse engineering many different fittings, including a new fitting on an OGP and then on a CMM.
Later I talked to one of the machinists who supported out group at work who ran the Screw machine shop at San Leandro's plant and was able to dig up some tooling to confirm this.

Old mag i appreciate your info, i've already converted all my old cats to air quip truck line but i left about two inches of the half inch copper line with the cat ferrul on it and i syl flossed a fitting on it to go to braided line much better than the old cat pipes to the tank. would it be better to leave the socks in the housing as second dary filter and change them maybe yearly
or leave them out all together since a cummins fleetgaurd 1000 is 10 micron and water seperator in one ? thanks again for everyones input.

You have done the same thing that I have done on most of my tractors, reused the ferrule and converted the fitting. I still run the sock filters. It always
bothered me that the relief valve on the transfer pump would recirculate junk over and over through the pump until Cat finally figured out that relocating the relief valve downstream of the sock filters would take care of that.

CR, never noticed the double angle, other than might be interpreted from worn seating. Certainly isn't required.

Later tractors had the primary filters on them and also all the OTR trucks that came in had the primary filters on them but they are no substitute for the original secondary filters so they need to be changed at the specified service time of them. Most if not all the primary filters that I saw at the shop were just a fine metal screen element and they weren,t meant to filter the very fine particles of dirt like the secondary system does.The main line to the transfer pump isn,t needed to be cut at the transfer pump fitting but should be installed before the fitting and places where you have room to install the primary base.Any type fittings to adapt it is all that required to the main feed line from the tank.