I stopped my 305 from hemorrhaging!

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by aandpman, Dec 27, 2002.

  1. aandpman

    aandpman 1/2 ton status Premium Member

    Sep 6, 2001
    Likes Received:
    Austin, Texas
    Ever get just downright P.O.'d /forums/images/graemlins/angryfire.gif at your /forums/images/graemlins/truck.gif for bleeding all over the driveway? Do you routinely have to give it a 30-weight transfusion?
    Well I may have found the answer that some of you have been praying for

    It is pretty common for the wimpy /forums/images/graemlins/crazy.gif 305 s.b. to leak oil from the rear main and oil pan and suck through the PCV breather tube into the air cleaner *if* you have done any mods at all to the induction (like aftermarket carb, etc). It seems that the PCV system just doesn't have a lot of oomph anyway so any imbalance can cause it to start spitting up oil.
    I've had the truck for about 5 years now, and I could NEVER get the leak to stop /forums/images/graemlins/confused.gif. I've put in countless PCV valves, oil pan gaskets, and even a rear main seal hoping to stop the bleeding, all to no avail.

    My truck has a 600 Holley /forums/images/graemlins/ignore.gif on a stock manifold with one of those 3/4" aluminum open-plenum adapters. Some years back I had to add a vacuum port by drilling into the front of the adapter and inserting a fitting becauuse I didn't have enough vacuum ports with the Holley to accomodate everything. The PCV system was sharing that port with things like vapor cannister.

    A few weeks ago I had the Carb off and I got the bright Idea of adding another Vacuum port at the rear of the spacer. This one I made larger than the previous one. (Sorry I don't have exact measurements handy). It was of sufficient size to handle the hose from the PCV valve by itself.

    Viola /forums/images/graemlins/smile.gif ...No more oil leaks. No more peeing on the driveway.
    No more oil soaked breather elements.

    It just needed more SUCK to balance out the crankcase pressure.

    I used to think that if it wasn't leaking oil that meant it didn't have any. Now I check it JUST FOR THE HECK OF IT /forums/images/graemlins/thumb.gif
  2. Sandman

    Sandman 3/4 ton status Author

    Apr 15, 2002
    Likes Received:
    Pocatello, ID
    Glad you found it. /forums/images/graemlins/thumb.gif

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