Leak on back of manifold? ???

Small Block Mopar Engine

  1. stackattack

    stackattack Active Member

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    I recently bought this car with an LA 360 motor and an Offenhauser intake manifold. It has a small leak i thought was from valve cover but looks to be from a 3/8" brass fitting into a 1/8" line that is on the very rear of the manifold. Tracing the 1/8" line appears to then go into the firewall. ??? Anybody have any idea what that is (or should be?) I was able to tighten it about a full turn and clean it off so I will see now if it is still leaking any.....when I retest I'll get a photo....
     
  2. toolmanmike

    toolmanmike FABO MODERATOR Staff Member FABO Gold Member

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    Yes, we need a photo. The oil passage for the sender is at the rear by the distributor.
     
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    • K.O. SWINGER

      K.O. SWINGER Meeting in the alley since 1976

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      That most likely is an oil pressure gauge sending unit line. You could just plug it with the appropriate plug till you're able to either repair or replace leaky fitting or line.
       
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      • stackattack

        stackattack Active Member

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        Roger that. I thought maybe thats what it was going into the firewall like it is. The 1/8" line is almost clear and its definitely oil in that line. The gauge is reading almost 100psi on cold start and takes a few minutes to settle down with a high idle. So i was thinking vacuum leak....until i saw that oil burning off the back running down into the steering rack.... :(
         
      • K.O. SWINGER

        K.O. SWINGER Meeting in the alley since 1976

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        Yes I was never a fan of the vinyl lines and always use a solid copper one. They are notorious for leaking but as I mentioned no big deal you can buy the parts at just about any part store
         
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        • eekvonzipper

          eekvonzipper My Member is Legendary! FABO Gold Member

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          Is there any worry that a copper line will break on a hard launch?
           
        • Locomotion

          Locomotion Well-Known Member

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          Best set-up would be a braided line for the application. A hydraulics store may be able to provide a conversion if they have all of the associated fittings. They may even have cheaper, but just as good, alternatives to the braided stainless style. I believe oil pressure lines would have a liner.

          The rear intake manifold rail seals are also known to be a leak source.
           
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          • stackattack

            stackattack Active Member

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            Thanks for the tips, everyone. There was definitely oil on top of the brass oil sender fitting and the stud in the intake for it. I spent a while tonight just before dark with a rag and screwdriver wiping off as much as I could get out of there. I'll wait til better light tomorrow and run her a bit and see if 1) the leak stops or if there's more coming from elsewhere and 2) if that impacts the higher idle at all. Anyone think that bit of leak in the oil sender at the rear of the manifold will cause a high idle condition??
             
          • stackattack

            stackattack Active Member

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            insp5f85e8f3082cd0.13870190.jpg
            insp5f85e9ee152441.17800979.jpg


            I'll try to get better photos of the exact problem area, but here's what I'm working with. 65 'cuda - my new project.
             
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            • K.O. SWINGER

              K.O. SWINGER Meeting in the alley since 1976

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              I've never have that problem just leave a little slack in the line
               
            • diymirage

              diymirage HP@idle > hondaHP@redline

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              Exactly why I only use electric gauges
               
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              • James Clews

                James Clews Well-Known Member

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                You have a steering rack on your 65 cuda? I would like to see a picture of that!
                 
              • flyfish

                flyfish C8H18+N2O = :-D

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                No. To pass tech at an NHRA track you can't use those plastic lines, you have to convert to some solid type (or go electronic). I have had a copper line on my street/race car for 27 years, no issues at all....and my car launches HARD.
                 
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                • fratzog lover

                  fratzog lover Well-Known Member

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                  10.19? Yes it does launch hard.
                   
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                  • JDMopar

                    JDMopar Well-Known Member

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                    If you use copper line for the oil pressure gauge, just make 2 turns around a big socket to give the line a place to flex. Kind of like brake lines are made at the master cylinder. It gives you some slack if you ever have to replumb it also! @stackattack Nice Barracuda!
                     
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                    • rigger3006

                      rigger3006 Well-Known Member

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                      i got my braided stainless line from summit, works great, i think it even came with a grommet for firewall
                       
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