Question about Edelbrock RPM Airgap - thermostat housing leak

Discussion in 'Small Block Mopar Engine' started by MileHighDart, Oct 2, 2018.

  1. MileHighDart

    MileHighDart FABO Gold Member FABO Gold Member

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    Well I keep going out in the garage and finding a puddle of antifreeze in my thermostat housing, and a big puddle in the valley of the airgap manifold. Manifold is new, thermostat and housing are new, put it together with permatex ultra gray.

    I think its seeping up around the threads of the bolts, but cant remember from when I put it together. Do the bolt holes go clear through into the water jacket? Anybody have one on the bench they could look at?

    IMG_2156.JPG
     
  2. B3422w5

    B3422w5 Well-Known Member

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    Typically the reason for a TStat housing leak is the mating surfaces arent flat. Real common with the chrome ones.
    I would make sure the mating surfaces are square. If you use sealer, permetex makes a specific sealer for thermostat housings.
     
  3. 4spdragtop

    4spdragtop FABO Gold Member FABO Gold Member

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    Goop the bolts too. You could even do it after draining some coolant. Try without removing housing 1st.
     
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    • dgibby

      dgibby Well-Known Member

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      Mine do not go through.
      Run a file over the housing when you get it off and make sure its flat and don't over tighten it.
       
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      • 69_340_GTS

        69_340_GTS Well-Known Member

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        The only way I've ever gotten them to not leak was by replacing the housing with a billet aluminum one that seals with an o-ring. All the steel ones, like yours, and the die cast "chrome" ones totally suck.
         
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        • mderoy340

          mderoy340 Well-Known Member

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          Mine do not go thru, but one of them was tapped at an angle.
           
        • tonysrt

          tonysrt FABO Gold Member FABO Gold Member

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          I had that problem with the cast housing, went to the speed shop and looked at Mr. Gasket housing and gasket surface looked machined flat, installed it and no more leaks. The billet are good but pricey compared to the Mr. Gasket, which I think was less than $20.00.
           
        • OL DODGE

          OL DODGE Well-Known Member

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          i just used a factory style thick aluminum one on my Air Gap and it isn't leaking (yet) and am kind of surprised ......................
           
        • AJ/FormS

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

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          Over the years it may be that several mechanics have filed the housing, and the stat recess is no longer deep enough. Resist the urge to double up on the gasket; restore the depth to receive the stat.
          I usually install studs in my aluminum intakes. On the top I install those special washers that Mopar used to retain the slanty exhaust manifolds.
          I have noticed that my aluminum stat housings warp over the years, so I file them with a bit of a crown between the mounting holes. And that means I get to deepen the stat recess, again
           
        • harrisonm

          harrisonm Well-Known Member

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          I fought the same problem for a few years. I finally bought the Billet Specialties billet T Stat housing (about $65) with an O ring. It has never leaked.
           
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          • Ottmundr

            Ottmundr 68 Fastback

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            This is what I'm running.

            Mine is clear coated aluminum, but you can get them in different colors. Red, blue, aluminum, black. I think I paid around $80, but it was worth it.

            CVR Thermostat Housings

            cvr_waterneck.jpg
             
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            • Bobzilla

              Bobzilla Well-Known Member

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              Any chance the hose itself is leaking down onto the housing?
              Looks like a Magnum Air Gap manifold and housing. I don't see too many of those leaking but the Chinese made hose clamps often let a little coolant slip by right under the worm gear screw.
              Also, looks like you have crankshaft sensor bolts holding the housing. Maybe see if those are too long and bottoming out.
               
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              • pntastar69

                pntastar69 Well-Known Member

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                Just installed a new air gap using the stock cast housing. Orange Permatex on both sides of the supplied fel-pro gasket, no leaks.
                 
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                • diymirage

                  diymirage HP@idle > hondaHP@redline FABO Gold Member

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                  I had an issue on my plow truck
                  On the stock intake there was a recess cast in for the thermostat to sit in
                  Whenever we installed the edelbrock intake, that recess was missing, making it impossible for the housing to seal since it would teetertotter on the thermostat

                  Just something to look for
                   
                • MileHighDart

                  MileHighDart FABO Gold Member FABO Gold Member

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                  Bobzilla, It's been doing this for a few months, I have checked it several times and I cant see or feel any antifreeze leaking down from the hose connection. The bolts are definitely not too long, checked that before I put it together the first time.

                  AJ/FormS, both the manifold and the thermostat housing are brand new, so nobody has filed the housing, and this manifold does have a recess for the thermostat.

                  Thinking I might check into one with the o-ring, but haven't checked yet to see if they make one that's tall like the original magnum one.

                  IMG_20170527_121049550.jpg
                   
                • AJ/FormS

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

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                  I run at 7psi, so no problems.
                   
                • MileHighDart

                  MileHighDart FABO Gold Member FABO Gold Member

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                  Update: So after getting the housing back off, and getting all the old silicone and gasket off.
                  I tried just sitting the housing on the manifold, and it rocks back and forth from side to side. This housing
                  has a little raised ring on the surface, which apparently wasn't very flat.
                  Laid it on a sheet of 400grit wet sand paper and after sanding and a few test fits, it now sits perfectly flat
                  on the manifold.
                  So grabbed a new gasket and some permetex ultra gray, I put it back together , finger tight, and waiting an hour like it says
                  before torquing it down.
                  I'm going to let it dry 24 hours before refilling with antifreeze, and we'll see what happens.

                  IMG_2161.JPG
                   
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                  • cookietruck

                    cookietruck Well-Known Member

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                    oh ha, it wasn't the bolts that were leaking, it was the two little channels by the bolt holes. hope you put plenty of rtv right there...
                     
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                    • 69_340_GTS

                      69_340_GTS Well-Known Member

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                      What a stupid way to make that housing. Guaranteed to leak. Put something different on there. Anything but that.
                       
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                      • MileHighDart

                        MileHighDart FABO Gold Member FABO Gold Member

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                        Does seem weird that they would leave gaps in that raised ring. Anyway it’s back on there now, I’ll go ahead and try it for a while and keep an eye on it. First sign of a leak after this and I’ll order one with the o-ring. Or maybe I’ll just go ahead and order it so I have it on hand.
                         
                      • 1994redram

                        1994redram FABO Gold Member FABO Gold Member

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                        I’ve never had an issue with the OE magnum housing leaking. I bought a new housing from the parts store when I installed my edelbrock intake, it hasn’t leaked either. New ones are pretty cheap and should be readily available at your parts store.
                         
                      • nm9stheham

                        nm9stheham Well-Known Member

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                        Yeah... I can't figure out a good reason to do that.
                         
                      • MOPEkidD-3

                        MOPEkidD-3 Torsional Member

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                        The stamped steel housings are junk. I've had great luck with simply using cast ALUMINUM parts-store replacements; make sure they're flat, put some gray RTV on both sides of the paper gasket, lightly snug it down, then come back in a couple hours and tighten the bolts fully. Worked like a charm on multiple Edelbrock SBM intakes I've used; get it once and never worry about it again.
                         
                      • diymirage

                        diymirage HP@idle > hondaHP@redline FABO Gold Member

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                        i think you will find that more then a few of us will take a thermostat housing out of the box, inspect it, and then decide to file it
                        and after seeing the picture of the housing i think most of us would have stuck it right back in the box and said "nope"
                        BUT the rest of us would have filed the snot out of it to make sure it was flat before installing it the first time

                        and lets be honest, thats how you're going to treat the next one, isnt it?
                         
                      • MileHighDart

                        MileHighDart FABO Gold Member FABO Gold Member

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                        Your probably right, or like I say, i'll just buy the one that uses an 0-ring