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Pretty sure I have a failed bypass diaphragm

Discussion in '348/355' started by FCOnyx, Oct 27, 2013.

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  1. FCOnyx

    FCOnyx Formula Junior
    Owner

    May 28, 2012
    413
    Round Rock, TX
    Full Name:
    Jeff
    #1 FCOnyx, Oct 27, 2013
    Just wondering if others can verify according to my symptoms.

    Noticed this weekend that the car suddenly sounds *much* louder when idling or cruising at a steady speed, sort of a drone that is always present.

    I have a Capristo III, so it's always been loud and still "howls" under heavy throttle, but now it's also loud even when not under load, which made me think the bypass (also a Capristo, so it would have failed open) is not closing.

    I pulled the airboxes and verified that the valve can still be actuated manually by pressing up on the armature (should the default position be extended downward, away from the diaphragm?)
    I pulled the vacuum hose from the diaphragm and tried blowing and sucking (haha, that sounds rude!) on it gently. I can hear the diaphragm making a popping sound as the pressure changes, but the armature does not move. Makes me think the diaphragm has failed inside. Right now the car is still too hot to pull it apart and see what it looks like inside, just thought I'd see if this is consistent with a failed (torn?) diaphragm.
    And if so, what is the replacement part path we like the best?
     
  2. CANDREAM

    CANDREAM Canada

    Nov 13, 2009
    407
    Burlington, Ontario
    Full Name:
    Sadi
    #2 CANDREAM, Oct 29, 2013
    I have the same set up.

    few ways to check......

    let the car idle for a few seconds and pull the vacuum hose from the top of the valve. If the sound changes/see the arm moves/valve open.....then it is working. Sound should get louder.

    Also other simpler way....check your exhaust tips......Only outer 2 should be blowing exhaust if the valve is closed....ie vacuum working/sucking. if all 4 tips exhaust....then the valve is open (ie: not working properly).

    If the valve is not closing at idle......You might have a simple vacuum leak....follow the tubing from the valve and see if all is well connected.....or...solenoid (near rear passenger wheel) issue.....may need a new one......

    Aslso, to check the diaphragm....you should disconnect the vacuum tube frm the top, move the arm manually and put your finger/close the top inlet. If it holds open, then the diaphragm should be is OK.

    Process of elimination.....
     
  3. gothspeed

    gothspeed F1 World Champ

    May 26, 2006
    10,244
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    goth
    #3 gothspeed, Oct 29, 2013
    Check if the actuator canister itself has a leak, by using a hand vacuum pump. Or if you are brave, you can pull vacuum on it with your mouth and a clean piece of test hose. As was mentioned above, watch for actuator movement when vacuum is applied. The engine does not need to be on, in order to vacuum test the actuator on its own.

    I believe the cappy bypass also uses a solenoid to control vacuum the the actuator. So testing the actuator directly, should give you an idea of what if anything has failed.
     
  4. FCOnyx

    FCOnyx Formula Junior
    Owner

    May 28, 2012
    413
    Round Rock, TX
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    Jeff
    #4 FCOnyx, Oct 29, 2013
    Thanks Can and Goth,

    I thought about the exhaust tips and checked them right after my initial post. Definitely getting output from all 4 all of the time. Again, pointing to the valve never closing.

    Pretty sure it's the actuator. It won't move the armature when I apply a vacuum (via mouth on the tube) to it. Also won't hold a vacuum if I move the armature manually then put my finger over the hole at the top. Seems like the internal membrane is probably torn. I have a new actuator on the way from Capristo at the moment. Should be here Friday. I'll know for sure once I get it swapped out.
     
  5. gothspeed

    gothspeed F1 World Champ

    May 26, 2006
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    goth
    #5 gothspeed, Oct 30, 2013
    I agree, the actuator diaphragm has failed ... :eek:
     
  6. Big Lebowski

    Big Lebowski Formula Junior

    Jan 24, 2013
    337
    Peach state
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    Brownie
    #6 Big Lebowski, Oct 30, 2013
    I just installed a new capristo bypass valve I purchased from T Rutlands and noticed that it is much louder at idle than the rattling OEM valve I had. Since it is new I guess I have a vacuum leak?
     
  7. tr512

    tr512 Formula 3

    Apr 12, 2007
    1,600
    canada burnaby bc
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    Michael
    #7 tr512, Oct 30, 2013
    I have the whole by pass valve and the diaphragm is good and holds vacuum $300.00 if you need it.
     
  8. FCOnyx

    FCOnyx Formula Junior
    Owner

    May 28, 2012
    413
    Round Rock, TX
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    Jeff
    #8 FCOnyx, Oct 31, 2013
    Thanks tr, but I think I'm covered. My bypass is fine and a new actuator should be here tomorrow for me to install. I've tested enough things that I'm fairly confident the actuator will take care of the issue. (fingers crossed)
     
  9. gothspeed

    gothspeed F1 World Champ

    May 26, 2006
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    #9 gothspeed, Oct 31, 2013
    I believe the cappy bypass is configured to be open when there is no vacuum. Where the opposite is true for the OEM. However I am not certain if all cappy bypass valves are configured this way. Did your new bypass come with a new solenoid?

    I would not run the car very much, if the valve is open during idle or low RPM. Check to make sure the hoses and check-valves are routed correctly. Did the cappy valve come with any instructions?
     
  10. FCOnyx

    FCOnyx Formula Junior
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    May 28, 2012
    413
    Round Rock, TX
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    Jeff
    #10 FCOnyx, Nov 2, 2013
    Yup! That was it. Sounds great now. And now to go enjoy a fantastic weather day! Thanks for all the input, guys!
     
  11. gothspeed

    gothspeed F1 World Champ

    May 26, 2006
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    goth
    #11 gothspeed, Nov 2, 2013
    Great news man!!! :)
     
  12. FCOnyx

    FCOnyx Formula Junior
    Owner

    May 28, 2012
    413
    Round Rock, TX
    Full Name:
    Jeff
    #12 FCOnyx, Nov 2, 2013
    Thanks Goth. Been nice to enjoy driving it again and not feel like I'm blowing the neighbors out as I come/go from the house.

    FYI, I contacted Capristo in FL and they sent out the new actuator. It was $150 (including $25 to have it shipped 2-day).

    I know that there are porsche actuators from ECS Tuning that are only $100, but I didn't want to deal with the long armature modification and wanted the Capristo version which has a small heat shield to hopefully keep it from failing again soon. I was also concerned that the Capristo valve might want a certain increased strength to contend with its spring tension, etc. So I figured since I didn't have an OEM valve, getting an identical replacement to what Capristo used originally would be the best bet. Worked like charm.
     

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