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Bleeding fuel lines 3208

Discussion in 'Technical Discussion' started by perdiem, May 3, 2011.

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  1. perdiem, May 3, 2011
    #1
    perdiem

    perdiem New Member

    Joined:
    Jul 28, 2009
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    Location:
    Victoria, BC
    I have a pair of Cat 3160 engines (older version of 3208 NA) and I always bleed the fuel lines by opening the line just after the filter and pumping the hand pump until clear fuel flows. I'm having some other work done and the mechanic said not to open the fuel line - just pump until you hear a squeak and that is the fuel getting by some check valve or something and it is primed. Does this sound right?

    The next day the shop manager phones and tells me that the fuel lift pump (about 3 years old) is spewing diesel. I think it is because he pressurized it by pumping fuel into it without the fuel having anywhere to go.

    Any help is appreciated....
    Gregg
  2. timvail, May 3, 2011
    #2
    timvail

    timvail Senior Member

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    Mar 15, 2010
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    georgian bay penetanguishene
    Seems to me that if you have been bleeding the lines as you have in the past with no problem???? Then why does the shop now have a problem doing it their way. Have only delt with perkins, but have always bled the lines as you have. Never heard of a check valve in that location before.
  3. dennismc, May 3, 2011
    #3
    dennismc

    dennismc Senior Member

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    Location:
    Vancouver BC
    bleeding fuel lines

    I was always warned about pressurizing the inlet side of fuel pumps against a dead head as it could cause problems.
  4. K1W1, May 3, 2011
    #4
    K1W1

    K1W1 Senior Member

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    Hi,

    As a boy and thru 10,000 hrs as an Apprentice I always loved CAT because you could always change all filters and then operate the priming pump till the F.O. Pressure gauge went full scale and just about guaranteed it would start first time every time if the particular machine was going to start at all.
  5. corinthian99, May 4, 2011
    #5
    corinthian99

    corinthian99 New Member

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    Jan 12, 2006
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    Location:
    London, UK
    Agree with K1W1 - only ever cracked the lines at the injector in extremis (and more to satisfy myself that the juice was actually getting there). Been through a few of those CAT priming pumps though, not the toughest but they are cheap and easy to replace.
  6. CatTech, May 4, 2011
    #6
    CatTech

    CatTech New Member

    Joined:
    Sep 28, 2010
    Messages:
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    Location:
    south FL
    on a 3208 fuel injection pump there is a check valve on the fuel return side that maintains fuel pressure in the system. this check valve should be overcome by the hand prime pump and not allow any overpressure of the fuel injector pump housing. Aprox 30PSI is when this valve opens. So not cracking a line as you have should not have failed the pump in any way.
    There is an easier way to bleed the system, on top of the fuel injector pump housing there should be a small tee handle valve that is connected to one of three small plastic drain tubes. Opening this valve bypasses the check valve allowing for bleeding the fuel injector pump housing of air without building the 30 PSI and excess fuel runs through the tube and can be collected. The other two plastic tubes are telltail tubes that when fuel runs from them indicate a leak of fuel into areas not designed to have fuel in them.