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Thread: 7.3 IDI fuel and oil leak

  1. #1
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    Nov 2009
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    Default 7.3 IDI fuel and oil leak

    Hi, recently bought a '90 F250 7.3IDI and it has a small oil and fuel leak. Truck and engine has 145K. Oil leak is coming from rear of engine. Fuel leak is dripping from rubber fuel lines connecting injectors and pump and collecting in glow plug galley area.

    1.) Any idea what might be leaking oil in rear of engine? It's only a few drips, not much, but I don't want it getting worse. Last owner just switched to synthetic oil and I am switching back to dino.

    2.) A Ford dealer checked out the truck and reported something like the fuel return line is wet, but fixing this might cause the IP to leak???

    3.) I'd like to think I can replace rubber fuel line to fix part of the fuel leak, but I have heard that getting air into a diesel fuel system is bad and just don't know if I will get air into the system while replacing these, and if so, what to do???

    Please help this new owner. Thank you!

    1990 F-250 HD XL SuperCab 4x4 7.3 IDI N/A ZF 3.55 Silver 165K

  2. #2
    Full Access Member motox tech's Avatar
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    Aug 2009
    granby, co
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    Mine leaks a little oil in the same spot your talkin about, I noticed my valve cover bolts were pretty loose the other day, and when I tightened those it slowed up some. I think the jest of it is comming from rear main, which is kinda expected on these older trucks.
    If your return lines are leaking, REPLACE THEM!! you can get a kit from a couple guys on this site( Agnem, Type4 ) or from an e bay store.(wouldnt suggest that) Your likely going to get air in your lines when doing this procedure, but thats not a big deal. (read the fuel injection service thread on home page) Your oil leak may be mostly diesel if its getting into valley pan!!

    94 f-350 crew
    Teal green (soon to repaint), 5" dual turnouts, strait 3" from turbo to Y, factory 94 ats turbo, 92 long block w/ 170,000, custom intake, 5 on the floor and a dent in the door!
    many mods to come!!

  3. #3
    Using the Force! Agnem's Avatar

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    Jan 2005
    Delta, PA
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    Classic problem. Start with the return line kit and read up on how to put it on.

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