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Thread: A fuel leak has sprung in the valley underneath the intake manifold on my 85 6.2...

  1. #1
    Join Date
    Jan 2025
    Location
    Midwest
    Posts
    10

    Default A fuel leak has sprung in the valley underneath the intake manifold on my 85 6.2...

    As the title states, a fuel leak has sprung down there, we already tore off the intake, turbo housing, however we couldn't find exactly where its coming from, I have a video of said leak, but its really hard to pinpoint, I hope its just a line, and not the IP itself.

    Any second opinions would really help, i did replace the rubber lines when I was in there, did not touch the metal lines though

    Attached are the videos of how it looked like/how it ran without the manifold, photos will be attached on this post aswell
    https://photos.app.goo.gl/N3HHPGKi3TeCws6w9

    Thank you again.
    (Also, I have some oil coming from the intake, bit uneasy about it)

    - 1985 6.2 Detroit Diesel Motor w/h ATS Turbo Kit
    Attached Images Attached Images

  2. #2
    Join Date
    Apr 2001
    Location
    Newberg Oregon
    Posts
    12,649

    Default

    Throttle shaft leaks are common on these....
    If you can get get a good look at the area right below the shaft you may find the gremlin.
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
    (1) 2005 Suburban (Papa Smurf)
    THIS IS BOW TIE COUNTRY

  3. #3
    Join Date
    Apr 2001
    Location
    CA
    Posts
    13,741

    Default

    Yes, the throttle shaft is a common suspect. If the IP or any line connections are leaking, they will be wet with fuel long before you'll notice any collection in the valley. Return lines are also suspect.

    Some oil in the intake is normal. The CDR (Crankcase Depression Regulator, the tuna can next to the oil fill pipe on your 85) allows some oil vapor into the intake. This does not mean it's bad. Some oils vaporize more than others, and more blowby (older, high mileage engine) is more crankcase pressure that passes into the intake, ahead of the turbo compressor, which may also have a coating of oil. The CDR's ONLY purpose is to prevent excessive crankcase vacuum (depression) at higher RPM's and other conditions, such as a fouled air filter or air inlet. Combine this with the EGR (if it's still working), will result in a gooey mess in the intake tract, but it's essentially benign, even after many years and miles.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

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