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    Lower Intake Manifold

    When the lower intake gasket fails on the lopo engines; where does the oil come from? The only thing I can think of is the pcv valve port. Other than that, wouldn't it just be coolant and a vacuum leak with a bad intake gasket? What am I missing? Just curious as both the '86 CV and the '91 Ranger had bad lower intake gaskets that puked oil down the back of the engine.

    #2
    oil leaks onto the bellhousing and down the timing cover usually. the seals in the middle of the intake usually go first.

    1986 lincoln towncar signature series. 5.0 HO with thumper performance ported e7 heads, 1.7 roller rockers, warm air intake, 65mm throttle body, 1/2" intake spacer, ported intakes, 3.73 rear with trac lock, 98-02 front brake conversion, 92-97 rear disc conversion, 1" rear swaybar, 1 3/16" front swaybar, 16" wheels and tires, loud ass stereo system, badass cb, best time to date 15.94 at 87 mph. lots of mods in the works 221.8 rwhp 278 rwt
    2006 Lincoln Town Car Signature. Stock for now
    1989 Ford F-250 4x4 much much more to come, sefi converted so far.
    1986 Toyota pickup with LSC wheels and 225/60/16 tires.
    2008 Hyundai Elantra future Revcon toad
    1987 TriBurner and 1986 Alaska stokers keeping me warm. (and some pesky oil heat)

    please be patient, rebuilding an empire!

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      #3
      Here are some pictures of the condition:





      The leak is probably coming from below the coolant passages where the manifold meets the top of the block. I think the original gaskets there were cork, and when I removed mine they came out in several crumbly pieces.
      1987 Lincoln Town Car - Signature, "Prudence"

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        #4
        The answers above both answer the question, but to add a little context: the valley of a SBF contains oil that is splashing around from the operation of the lifters/pushrods. This is why the front and rear seals/gaskets have oil behind them to begin with.

        In my non-exhaustive experience I've found the coolant leaks to be a bigger problem (in terms of volume and how often it needs to be compensated for). Coolant into the adjacent intake passage, or coolant escaping to the outside world. None of mine have put coolant into the oil yet but it is also possible, and would make the engine need a rebuild very quickly if it happened.

        Current driver: Ranger
        Panthers: 83 GM 2dr | 84 TC | 85 CS
        | 88 TC | 91 GM
        Not Panthers: 85 Ranger | Ranger trailer | 91 Acclaim | 05 Focus
        Gone: 97 CV | 83 TC | 04 Focus | 86 GM
        | Junkyards

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          #5
          Scott, Lutrova, and kishy; thanks for the clarification. Totally forgot about the actual lifter valley 1st gen sbf have. When I was thinking about this over the weekend, I was thinking along the lines of a 4.6 mod motor valley. What little time I spend on my MGM, seems to be too much time; as it is twisting my mind.

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            #6
            Those end wall gaskets are like 1/4" or so thick, so when the cork shrinks it makes a pretty good gap to leak from. The rubber seals work a lot better. Most pushrod V engines have the same basic design and tendency to puke oil from that spot.
            86 Lincoln Town Car (Galactica).
            5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

            91 Lincoln Mark VII LSC grandpa spec white and cranberry

            1984 Lincoln Continental TurboDiesel - rolls coal

            Originally posted by phayzer5
            I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

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              #7
              I'll add that if your PCV mesh filter becomes clogged, the cork gaskets will be the first ones to get blown out. Mine also came apart in crispy chunks when I redid the top end gaskets.

              My car also had an issue with the original oil pan gasket. The mesh was completely clogged causing pressure that blew out a corner of the oil pan gasket.
              —John

              1985 Ford F-150 XLT Lariat
              1990 Mercury Grand Marquis LS (POTM March 2017 & May 2019 - gone, but not forgotten)
              1995 Mustang SVT Cobra coupe (cream puff)
              1966 Mustang coupe (restoration in-progress)

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                #8
                That's what killed the lopo in the '86 CV. Clogged pcv screen that I couldn't remove; which in turn must have put pressure in the intake and valve covers. Put a lot of oil in the throttle body and coated the underside of the car all the way back to the rear axle. Kinda defeated the purpose of me painting that rear after the rebuild.

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