Newbie with 360 LA problem

Discussion in 'Small Block Mopar Engine' started by Rock Able, Sep 12, 2018.

  1. Rock Able

    Rock Able Active Member

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    I have a 41 Plymouth hot rod that I've been assembling for about 8 years. I just got around to cranking it a couple of weeks ago and I have an oil leak problem that is making me crazy.

    The engine is a mid 70's 360 with a rear sump oil pan. When I built the engine, I used a light blue one piece pan gasket, not sure of the brand. After driving it, it leaked around the front seal. Reluctantly, I installed a 4 piece seal set. The first time I tried it, the front seal kept slipping inward on the PS. The second time, I glued it in and let it sit overnight. I pulled it up square this morning and let it sit for a while. After taking it for a short run, I smelled oil again. When I got it up on the lift, both sides of the front seal had pulled in and broke the tits off the seal.

    I'm at the point now where I believe the Dorman rear sump pan has a bad flange on it......unless you can convince me otherwise. The problem is, rear sump pans are very limited and I don't have room for a deep pan. What are my options? Have you heard of this problem before?

    I cannot remove the engine without totally disassembling the front end and I do not want to do that, if possible. I can drop the front of the pan about and inch and a half and the rear 3-4". I may be able to drop the rear of the transmission and raise the front enough to get this pan off. I will investigate that tomorrow but for now, I'm looking for options. Thanks.
     
  2. AJ/FormS

    AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

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    put a vacuum gauge on the dipstick tube the next time you replace that seal, flip the PCV out and seal the hole, as well as the breather hole; Ima thinking your intake is sucking from the valley side. If it was, you should be leaving a blue trail behind you......... and it should be idling noticeably rougher than you would imagine with the cam of your choice.
    Unless you are running pan-evacuators.? These will not affect your idle quality, nor the blue trail.

    My 71 360 runs a different front rail seal, with huge lips that drape over the rails

    Just curious what cam durations
     
    Last edited: Sep 12, 2018
  3. brian6pac

    brian6pac Well-Known Member

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    What VC's are you running ? I seen the same thing with a guy that had a screw on fill cap and a PCV valve and no breather in aluminum VC's, never punched out the hole for the breather. Put so much vacuum in the crankcase that it kept sucking in the intake end rails.
     
  4. Jadaharabi

    Jadaharabi FABO Gold Member FABO Gold Member

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    How about the wrong pan? Are you using a 318 pan instead of a 360?

    Wait that would be the back of the pan that is differant.
     
    Last edited: Sep 13, 2018
  5. Rock Able

    Rock Able Active Member

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    It has Mopar cast aluminum valve covers that have been drilled out to accept Billet Specialties breather and PCV. The engine idles and runs smoothly with no weirdness. I have a hard time believing it's pulling a vacuum on the crankcase when that breather is unrestricted, no matter what may be happening with the PCV.

    This has the front seal with lips on both sides of the flange. The last one was glued to the flange...and no, this is not the wrong pan. I've built many engines from Porsche to Pontiac to ABC. This is my first Mopar but it isn't my first engine build. Something is definitely weird here, however.
     
  6. AJ/FormS

    AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

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    on closed-throttle deceleration,on flat level ground, with a manual trans,it is possible to see more than 25" vacuum in the intake. If that vacuum found it's way from the intake, into the crankcase, atmospheric pressure would be desperate to get in there.
    I would have thought your PCV hose would collapse first, if the breather was not functioning ,but ............... it's hard to point to that on account of in 50 years of wrenching I have only seen a few cases of excessive vacuum in the crankcase.Since you are familiar with engines you would know that the breather has to work in both directions, and the PCV is a tiny orifice. So even if the brearher was 100% not breathing, it would still take a fair bit of time to reduce the crankcase pressure to such a high degree, that the panrail gasket could get sucked in. Furthermore, it is very hard for me to imagine the whole gasket (you said both sides got sucked in, but I guess you meant both ends?),could get sucked in. I would have thought that as soon as the first corner let go, that, that would have been the end of it .
    So now I'm wondering if the rubber gasket was split, or if the glue you used affected it. I use RTV on the corners only and very sparingly, on account of I have seen RTV and rubber, not play nice together...... under pressure. I would have used 3M weatherstrip adhesive to glue the rubber down .

    IDK, maybe it was assisted by a 60mph wind from the front........ I'm grasping.....
     
    Last edited: Sep 13, 2018
  7. Rock Able

    Rock Able Active Member

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    I should have said both ends of the seal. I agree with everything you said. I think maybe the flange on this pan is not square but it is difficult to see without removing it. The breather is clear and I do have a manual transmission but I cannot see,how it can draw a vacuum with the breather working. The PCV cannot flow that much air.
     
  8. Rock Able

    Rock Able Active Member

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    Well, I inspected the PCV and there is lots of oil in the kine and the valve. I tested it on my truck and ut seems to be pulling full vacuum at idle. It should be restricting it some at idle. Correct? Now, I dont know if I have a pan problem or just a PCV problem.
     
  9. brian6pac

    brian6pac Well-Known Member

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    What are you gluing it with? I have used super weatherstrip adhesive, the black not the yellow on many gaskets and they stick.
     
  10. Rock Able

    Rock Able Active Member

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    Used 3 M yellow glue. The good stuff.
     
  11. brian6pac

    brian6pac Well-Known Member

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    I would try a new PCV
     
  12. brian6pac

    brian6pac Well-Known Member

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    3M yellow, you can get the same thing in black and it doesn't stick out like a sore thumb, I think the # is 08008
     
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    • nm9stheham

      nm9stheham Well-Known Member

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      What type of idle vacuum do you measure in the intake? If it is low due to the cam, then the stock PCV will never close down at idle. The stock PCV is designed to close to the low flow mode with 14-15" of vacuum; not sure what the one you have is designed for.

      But you are right.... a nice open breather ought to keep the crankcase vacuum pretty low. So I am inclined to thing 'pan problem'. (Sorry.)
       
    • Rock Able

      Rock Able Active Member

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      It was pulling 16-17" at idle.
       
    • teringer

      teringer ase master hall of fame

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      do you have the baffle under the pcv to keep oil from going up the hose? are your rocker arm shafts oil holes pointing down ?
       
    • Rock Able

      Rock Able Active Member

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      Rocker shafts installed with notch pointing to crank as per instructions. There is no baffle in the 2 holes I drilled into the valve covers.
       
    • yellow rose

      yellow rose Doctor of Thinkology.

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      You need to baffle those holes.
       
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      • nm9stheham

        nm9stheham Well-Known Member

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        OK, just about ANY PCV valve should be closing down to idle flow with that amount of vacuum.
         
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        • Rock Able

          Rock Able Active Member

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          0913181435_HDR.jpg

          0913181435a.jpg

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        • Rock Able

          Rock Able Active Member

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          Wow!
           
        • Jadaharabi

          Jadaharabi FABO Gold Member FABO Gold Member

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          Improperly assembled and over tightened?
           
        • Rock Able

          Rock Able Active Member

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          No. High vacuum is my guess. Do you think that not having a baffle under the PCV caused that?
           
          Last edited: Sep 13, 2018
        • nm9stheham

          nm9stheham Well-Known Member

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          No.... not baffle would lower the crankcase pressure a tiny bit if anything. But probably no measurable effect.

          What are you using as a sealant? If straight RTV/silicone, that is not helping. Looks like it need to be a sealant that glues a sets, like Permatex #2.
           
          Last edited: Sep 13, 2018
        • Rock Able

          Rock Able Active Member

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          But it allowed the valve to fill up with oil.
           
        • nm9stheham

          nm9stheham Well-Known Member

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          That cork does look awfully flattened.