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97 3100 common vac leak points?

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  • 97 3100 common vac leak points?

    anybody know of some of the common points to start looking for vac leaks on the 97 3100? lets not include the LIM... thanks

  • #2
    Uhm... None that I know of other than the LIM... That's where my vacuum leak was back in the day. The plenum doesn't really leak since it has 12 bolts.. I'd check the emission lines like the PCV and the line that comes off the PCV line that goes to the charcoal canister purge solenoid, which is located underneath the coilpack on my motor. Other than that, there isn't much else I can think of unless you have a bad gasket from re-using one or something. But I've re-used my EGR, plenum, and TB gaskets tons with success...
    sigpic New 2010 project (click image)
    1994 3100 BERETTA. 200,000+ miles
    16.0 1/4 mile when stock. Now ???
    Original L82 Longblock
    with LA1, LX9, LX5 parts
    Manifold-back 2.5" SS Mandrel Exhaust. Hardware is SS too.

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    • #3
      ok thanks... actually i do know of one... in case anyone else reads this... I've seen it a few times where the little rubber gromet om top of the TB seems to soften up and either develop loosness or it begins to get sucked into the hole... so.. thanks for the ideas..

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      • #4
        Yeah mine was a little loose but when running it sucked down and caused no problems. I put some cut silicone hose as a spacer on top of it between the throttle cable linkage support bracket to hold it down tight though.
        sigpic New 2010 project (click image)
        1994 3100 BERETTA. 200,000+ miles
        16.0 1/4 mile when stock. Now ???
        Original L82 Longblock
        with LA1, LX9, LX5 parts
        Manifold-back 2.5" SS Mandrel Exhaust. Hardware is SS too.

        Comment


        • #5
          good idea... i've resorted to bending the bracket over top of it in the past, a little more of a butcher tactic....haha.... but anyways, I was hoping that it would be that gromet, so I held it in place and waited to see what would happen to the idle, unfortunately it had no effect. I'm pretty certain the PCM would be able to detect that change and provide a proper idle, but because I don't assume I'm right, I suppose it might be possible for the symptom to continue beyond a half minute or so??? seems unlikely though.
          the thing is here, my LIM does still leak... and I bought the car knowing that. Luckily it leaks a small amount of coolant outside of the engine, rather than into it... or so I've been told. I don't know how many different LIM syptoms there are, so I am wondering if you know of a scenario where a vac leak can exsist without coolant being drawn into the engine??

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          • #6
            If the coolant jacket area on the gasket is broke on the outer edge, coolant will flow outside the motor instead of into the cam valley. If the gasket around the intake ports is messed up, it can suck in air that is in the crank case which will pull air from the rear valve cover...

            Try some propane or carb cleaner spray in the rear valve cover hole and see if the idle shoots up...

            If not use that to check the plenum gaskets, TB gasket, etc. It's also possible to have a stuck IAC valve too but that might set a code.. I dunno..
            sigpic New 2010 project (click image)
            1994 3100 BERETTA. 200,000+ miles
            16.0 1/4 mile when stock. Now ???
            Original L82 Longblock
            with LA1, LX9, LX5 parts
            Manifold-back 2.5" SS Mandrel Exhaust. Hardware is SS too.

            Comment


            • #7
              i think your right on the IAC... it probably would throw a code, im gonna see if I can pull the car in the shop tommorow after work and get some propane to it... my portable canister is a pain in the ass though since tilting it causes it to stop flow... however, a sudden idea... the torches! ok.. thanks for the advice

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