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  1. #1
    Super Swamper
    Join Date
    Sep 2011
    Lake Forest, CA
    Thanked 551 Times in 378 Posts

    Code P0236, Vacuum pump, pulley, sensor, vacuum line

    On my way to Moab I lost turbo boost as we were beginning to climb on I-70. I quickly got a pending code P0236 and then that became a stored code P0236. I tried clearing the code with my scangauge and I tried disconnecting the batteries. Both "fixes" worked for a few minutes and then the code would come back.

    I made it to Moab (going uphill without Turbo in a 9000+ pound truck that's supposed to have Turbo is... uhm... it builds character) and started researching the code and possible causes. I quickly found info online that told me that it most likely would be the turbo wastegate actuator solenoid. I was about to have a new solenoid shipped in when Dave suggested we take a look at the vacuum pump itself and I'm glad we did: The pump was completely seized up, the pulley was jammed against the pump and the shaft was at an angle it's not supposed to be at. The pump & pulley couldn't turn AT ALL so my serpentine belt was sliding over the pulley and had gotten very shiny on the smooth side.

    I got a new vacuum pump and a new pulley and a special tool to press on the pulley (thanks to Mike at Tustin Hummer for shipping out parts so fast) and installed it all along with a new belt and a new tensioner pulley that I had with me (with the help of Matt & Dave)

    At this point it was now safe to run the engine again without the risk of a sudden failure of the belt but I still had no turbo boost.

    The next day I started looking at the vacuum system. I started by making sure there was a good strong vacuum coming off the pump and in to the solenoid. I also pulled the solenoid and checked to see if it was clogged by dirt and gunk but it wasn't. I traced the vacuum all the way and found that there was plenty of vacuum to operate the water valve for the HVAC. That was all well and good but I couldn't understand how come the vacuum line seemed to end at the water valve. There was supposed to be a vacuum line going to the waste gate.... but there wasn't....

    Wait, what? No vacuum line going to the wastegate from the solenoid? and Mike from Tustin Hummer was insisting that there is supposed to be one..... Well there's your problem! A bit more poking around in the valley of the engine and I found that the vacuum line from the solenoid to the wastegate had broken clean off. Quick fix: Add some new vacuum line to connect the two ends and BINGO: Turbo boost!

    I can't imagine that the line breaking off the solenoid had ANY relation to the vacuum pump seizing up, that's got to be coincidental.

    Ultimately, things are back in working order for the trip home and that's a very good thing.

    I have learned a lot about how my truck works on this trip and wrenched more on it than I ever have.

    Now I'm off to to re-check the bolts for the vacuum pump and the tensioner pulley as well as the vacuum line and then we are hitting the road back to CA tomorrow.
    2016 RAM 2500 Power Wagon
    1995 Jeep ZJ V8


  2. #2
    a.k.a. "The Jackal"

    Join Date
    Sep 2011
    Santa Clarita, Ca
    Thanked 2,204 Times in 1,208 Posts
    glad to hear you got it all worked out and that you learned some new things makes it even better!
    Squeaky3: 06 H3 ALPHA D70 front/Eaton HO72 rear 5.13 gears, custom crossmember for long arms, lockers, 4:1 T-case, v8 swap, hybrid cage, Warn 12k Custom bumpers....do it all vehicle

    "H3 front axles are like drunk cheerleaders....just use em until they get mouthy...then toss em and get another." -anonymous

  3. #3
    Super Moderator
    Join Date
    Sep 2011
    Central Texas
    Thanked 1,377 Times in 1,129 Posts
    Always good to know your truck is right before you begin that 750 miles return trip with 4 7000' summits, a 6000' summit and numerous 4000+' summits.
    1998 H1 Open Top
    1994 H1 HMC4
    1992 H1 HMC4 LE
    1990 1025 Armament Carrier


    BlackSheep Hummer Squadron, H1 PsychoSquad

  4. The Following User Says Thank You to 3Hummers For This Useful Post:

    LagunaH1 (10-10-2013)

  5. #4
    El Diablo
    Join Date
    Sep 2011
    Thanked 3,693 Times in 1,865 Posts
    Nice work and glad you got the turbo back

  6. The Following User Says Thank You to alrock For This Useful Post:

    LagunaH1 (10-10-2013)

  7. #5
    [o O IIIIIIII O o]
    Join Date
    Sep 2011
    Black Hawk, SD
    Thanked 305 Times in 251 Posts
    Our truck had a similar problem, but it was solved with a mechanical wastegate
    OLAN- "Hogget" - Black Sheep Hummer Squad

    1999 Hummer H1 (Black) l Sold
    2003 Hummer H1 (Black) l 2003 LB7 Duramax l Allison transmission l Alpha Interior l


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