Archived 1991 W250 Fuel Filter Housing Leak

[viktor skyler]

Owner: I'm an aircraft mechanic, and first owner of this 1991 W250. I do all my maintenance, and personally drove the 391,000 miles on the odometer.



Truck: This morning, I noticed a puddle, a leak from the stock/factory-type NAPA fuel filter. According to my felt pen mark, I re-newed it '02/06'.



I replaced it with one of my new-spares, a Luberfiner, including new gaskets, and it still leaked. I replaced it again (with new gaskets) with my other spare, along with the water-in-fuel sensor ($53 from DC), and it still leaks.



Here's the alarming part: The first leaking filter (this morning's 02/06) was severely rusted across the top inside. All visible metal surfaces were corroded, and the WIF probes were gunk coated. The outside of the original NAPA filter appeared as-new before I chucked it in the recycler.



The leak is a couple drops a second while the engine is running -- about a cup a minute runs down the WIF drain tube.



From under the truck with the filter removed, the mating surfaces look and feel smooth and clean.



What is the job of the thin plastic manilla-colored piece just inside the housing? a shield/diverter? What happens if it warps (although it appears fine)?



I'm headquartered in Cottage Grove Oregon, although I'm house-sitting in Concord California through August 4th '06, and drove this truck to California. I intend to drive it home -- no surprises.



Help!!!



thanks,

viktor skyler

(916) 806-3344

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1991 W250, automatic, AC, engine stock. 391,000 miles.

 

[bgilbert]

The piece you are seeing 'inside the housing' is the fuel heater. If it appears fine, then leave it alone. Have you determined exactly where the leak comes from? It could possibly leak from between the fuel heater and the cylinder head, between the fuel heater and the fuel filter, from one of the two banjo bolts that attach the fuel lines to the filter housing.



Things that can be replaced: there is a big o-ring between the fuel heater and cylinder head. Remove filter, remove the threaded filter adaptor with a big flat screwdriver or chisel, then the fuel heater will fall right now, replace o-ring. Each banjo bolt has two sealing washers on each side of each fuel line. These can be replaced if old and or leaking.



Make sure there is no old 'square cut gasket' on the threaded filter adaptor when replacing the fuel filter, then add a new gasket. I would start replacing fuel filters more often so as to not start a rust factory inside your fuel system. What do you think the inside of your injection pump looks like? Use some brake clean or ether and spray the assembly, dry with compressed air, then determine the source of the leak.