Forum Discussion

kenbert's avatar
kenbert
Explorer
Jul 14, 2015

Intermittent Turbo

Took a trip to PA this weekend, 4 hour drive. After 2.5 hrs when climbing , the turbo boost started to kick out. With the pedal to the floor the boost would go to 12, down to 5 then up to 12 then down to 5. Kept doing this through entire climb, was normal on level grade.

Pulled into rest area for a while and finished trip with no problems.
Coming home after 4 hrs driving, started the same problem. This time even did it on level grade. Boost would not come on till shifted into 3rd gear, and did the same thing. Boost would not hold, kept falling off.

I am hoping someone here has had a similar problem and give some tips on what to look for. Thanks in advance.
Class A
  • wolfe10's avatar
    wolfe10
    Explorer
    Jul 14, 2015
    A 1995 B will be mechanical, not electronic, not variable vane turbo.

    If turbo was loose on exhaust manifold, it could be rocking between tight and loose enough to let exhaust escape without turning the turbo. Unlikely, but worth a quick look for black soot. If a boot loose on intake side of intake side, no symptom until you get a "dusted" engine. No restriction on air (or on dirt!). If boot loose on CAC side of turbo on the intake side, you would loose boost.
  • Passin_Thru's avatar
    Passin_Thru
    Explorer
    Jul 14, 2015
    Does it have variable vanes. If so they are probably stuck. You can go to Cummins or Dodge forums and search ways to free them up.
  • Executive45's avatar
    Executive45
    Explorer III
    Jul 14, 2015
    Brett, if the turbo was loose and sucking air wouldn't the check engine light come on..:h. Or, because it's intermittent there's not enough "issue" for it to be triggered..?:h/ thanks... Dennis
  • kenbert's avatar
    kenbert
    Explorer
    Jul 14, 2015
    You can see the engine in my signature, 5.9 Cummins. Checked all connections and hoses, all looks good. Why would it clear up after a rest. Did have some issues with Pac Brake sticking, relubed and good. when i did have the problem with Pac Brake it did not affect the turbo.
    Also not a gauge problem.
  • donn0128's avatar
    donn0128
    Explorer II
    Jul 14, 2015
    New turbo time is my guess. Possibly the turbo is sooted up, and if your handy you might be able to drop it out and clean it. What motor? What sort of emissions?
  • wolfe10's avatar
    wolfe10
    Explorer
    Jul 14, 2015
    First question is this a gauge issue, or did HP drop off when this happened (meaning boost REALLY DID drop off)?

    If you have an exhaust brake, confirm that it is moving freely and not sticking closed or partially closed.

    Last easy/inexpensive issue is to make sure that there is no exhaust leak between engine and turbo (loose bolts holding the turbo on could allow the turbo to get good exhaust flow/then poor.

    And, look at the plumbing on intake side from turbo through CAC and to the intake manifold.

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