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420A Oil leaking from Camshaft sensor, still leaking after replacement

Posted by MeteorBurn, Jan 11, 2019

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  1. MeteorBurn

    MeteorBurn Proven Member

    39
    6
    Joined Jan 9, 2016
    Columbia, Maryland
    Hey guys,

    I recently got all the major engine gaskets replaced and now the engine is 98% leak free, but I still have one last nagging issue. The stupid camshaft position sensor was leaking a tiny bit of oil, so I replaced the o ring with a new felpro one. Nope, still leaked. Ok, this time I made sure I cleaned the mating surface on the head spotless, I bought a brand new NTK sensor that came with a seal, torqued the bolts to spec, nope, STILL LEAKING. Okay, third times the charm. I cleaned the head again, cleaned the sensor carefully, and put a thin coat of ultra black rtv on both sides of the o ring. I installed the sensor, torqued to spec, let it dry overnight, and when I went to start it up, it's still freaking leaking!

    The valve cover was recently changed, oem gasket and rtv in all the correct places and I know it's not coming from above the sensor. Using an inspection mirror I can see a small bead of oil emerging from right under the right hand bottom corner of the sensor. Has anyone else had this problem? Besides the valve cover, is there anywhere else this oil could be coming from? Cam bearing cap or something? I just have no idea why it keeps leaking. I don't want to make it tighter because the plastic cracked on the OEM sensor very easily.

    The sensor is not cracked or anything, I cleaned everything meticulously, there are no gouges on the mating surface, I let the RTV dry at least 13 hours, I torqued it to 26 in. lbs (from FSM) and it still keeps weeping. The last idea I have is to get an OEM seal and "the right stuff" black RTV (supposedly better sealing than regular RTV) and be a little more generous, but I'm at a loss.

    Any help would be greatly appreciated.
     

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  2. Vegas smith

    Vegas smith Proven Member

    2,310
    1,033
    Joined Dec 2, 2002
    Houston, Texas
    I can't view the FSM right now, but doesn't it say to put some sealant under the cam caps (underneath bolt)? Maybe that's your problem.
     

    Street Build 2K  10

    1993 Eagle Talon TSi AWD
    awd · manual · 1G DSM
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  3. silvreclips

    silvreclips Proven Member

    841
    54
    Joined Jul 19, 2005
    Greenville, South Carolina
    I second the oil leak coming from the cam bearing cap. I had this exact same issue and did exactly as you did. It ended up being the bearing cap leaking oil. Go ahead and put a new valve cover gasket on again. In my experience if you ever take them back off they start to leak again. Even if almost new.
     
  4. EVLGSX

    EVLGSX Proven Member

    208
    59
    Joined Dec 7, 2017
    Wallingford, Connecticut
    Fel-pro or OEM Valve cover gaskets can be reused so long as they are intact and the rubber is still supple. I would not waste my time with any other. A drop of black rtv needs to be placed in a few key locations, along with grey RTV at the cam sensor. I use a thin layer between the surfaces of the cam angle sensor components, and light coat the triangle gasket ive reused countless times. The outer caps needs a drop of black in the corners. If you spend a moment considering this, while looking at it, it should become very clear. I have never had a single leak from any part of the cylinder head when following what the factory service manual explains.
     

    Street Build 838  15

    1997 Mitsubishi Eclipse GSX
    awd · manual · 2G DSM
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  5. MeteorBurn

    MeteorBurn Proven Member

    39
    6
    Joined Jan 9, 2016
    Columbia, Maryland
    Thanks for the replies guys. That makes total sense considering there's no way it could leak after 3 attempts, its just a simple o ring. Is there much complication involved in removing the camshaft end cap? It can just be unbolted, cleaned, and rtv'd? Do I have to remove the magnet on the end of the camshaft? I just really want to do this right and be done with it, I'm absolutely sick of oil leaks.
     
  6. EVLGSX

    EVLGSX Proven Member

    208
    59
    Joined Dec 7, 2017
    Wallingford, Connecticut
    take the whole assembly apart. start with the 3 bolt cover , under the cover you will see the part of the assbly the magnetic pickup reads-Held in by 1 12mm bolt, take a photo before you pull it , it can go in 2 ways, be sure to put it back the way it came out. now you can unbolt the housing from the head. Clean it all up good and you know the rest.....

    heres this too:

    http://www.dsmtuners.com/threads/2g-cam-sensor-install-angle.382756/
     

    Street Build 838  15

    1997 Mitsubishi Eclipse GSX
    awd · manual · 2G DSM
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  7. PlanZero

    PlanZero Proven Member

    1,373
    257
    Joined Aug 13, 2013
    Easton, Pennsylvania
    OP has a 420a.
    I know how you feel.
     

    Street Build 3K  8

    1996 Eagle Talon TSi
    fwd · automatic · 2G DSM

    Street Build 2K  0

    1997 Eagle Talon TSi AWD
    automatic · 2G DSM
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  8. MeteorBurn

    MeteorBurn Proven Member

    39
    6
    Joined Jan 9, 2016
    Columbia, Maryland
    Yeah, no one ever has a freaking 420a, it's always 4g63, 4g63, 4g63!
    giphy.gif
     
  9. MeteorBurn

    MeteorBurn Proven Member

    39
    6
    Joined Jan 9, 2016
    Columbia, Maryland
    So after reading the FSM again, it seems all I really have to do is take off the 3 bolts holding the camshaft cap, put some anaerobic rtv under the edge of it, torque back to spec, and I should be good?
     
  10. silvreclips

    silvreclips Proven Member

    841
    54
    Joined Jul 19, 2005
    Greenville, South Carolina
    That should be all.
     

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