Blowing IAC gaskets. Bummer.


  • Blowing IAC gaskets. Bummer.

    So, I was running on about 5psi of boost on my vg33et. I upped it to 7.5 today, and after only about 4 pulls, it blew 2 boost leaks. one in the boost gauge reference line, and one of the IAC gaskets. Was it just a fluke, or is this a common problem? If so, how do people solve it? inb4 delete the IAC, I want to keep it.
    09 Lancer ES 5 speed
    86 Z31 VG33E(NA2)T.

    "I want it to sound like the pits of hell are going to engulf your face!"

  • #2
    New question. Upon checking courtesy nissan, I found that they have 2 different part numbers for turbo and non-turbo IAC gaskets. I asked my local dealership for the turbo gaskets, but they may have gotten me NA. What are the differences, if any? The ones I had were just paper gaskets.
    09 Lancer ES 5 speed
    86 Z31 VG33E(NA2)T.

    "I want it to sound like the pits of hell are going to engulf your face!"

  • #3
    Id check with a small straight edge to see if both surfaces are flat. Had an issue like this on my friends DSM. But I think my issue was just isolated to our ride lol.
    My Build Thread

  • #4
    leaks happen. its normal.

  • #5
    This is why I use RTV…and block off plates.
    - VG30DET (HE341) 86 300ZX - 1982 280ZX Turbo - Headered NA 1986 300ZX 2+2 - 2000 Xterra -

  • #6
    I use paper gaskets just fine. I actually cut my own, and smear a bit of fresh oil on them by hand to make them compress a bit more. Seems to work for me.

  • #7
    I had put some Permatex gasket sealant on them before installation. I'm going to order 2 more and replace them, and see if it happens again. It just seemed odd to me that they would give out at such a low pressure.
    09 Lancer ES 5 speed
    86 Z31 VG33E(NA2)T.

    "I want it to sound like the pits of hell are going to engulf your face!"

  • #8
    Isn't the IAC one of those "unnecessary" parts anyway?
    Prius… because Pretentious wouldn't fit across the back of the car…

    Cheap, Fast, Reliable - pick any two

    My 1986 Turbo Build

  • #9
    I just had my plenum welded shut. Nothing is really "Unnecessary". It controls the fast idle I believe. So it does serve a purpose. But, if you're like me, it's useless for my application.


  • #10
    On the subject of IACs, I like having mine because the car's a DD and it's just a bit more civilized with it (I have ran it unplugged so that's my point of comparison.) But I'm wondering. If I wanted to run custom intake piping (since I have piping and connectors in the basement, and the AC compressor's gone so I could make a nice straight-shot intake in half an hour), could I just slap a filter on the IAC intake that's coming from the S-pipe right now instead of plumbing the custom piping?

    It'll be unmetered air, but VG30Es run rich anyway and it's not like I am going to get detonation on my NA motor in any situation where the IAC would be open. The worst I am going to get by trying this is a fast cold idle, right? I guess the real risk is that a failing IAC valve = constant lean condition, but I'm gonna notice that from the idle going ZOOM and the motor's NA right now anway so blowing it up just from that would be a real challenge… or is this overly optimistic…?

  • #11
    -Strike-;326703 wrote: I just had my plenum welded shut. Nothing is really "Unnecessary". It controls the fast idle I believe. So it does serve a purpose. But, if you're like me, it's useless for my application.
    I was thinking of the one on the other side. This one is more necessary than some of the others, but can be eliminated.
    Prius… because Pretentious wouldn't fit across the back of the car…

    Cheap, Fast, Reliable - pick any two

    My 1986 Turbo Build

  • #12
    Ahh, the Air Regulator. You're right, that's the cold start fast idle. Had it mixed up with the FICD/AAC on the other side that controls idle stability during higher engine loads. Mine is gone too, hah.

    Basically I start the car, and bam she's already at low idle. If it's really cool, you could have some stumbling issues until it warms up a bit.


  • #13
    -Strike-;326716 wrote: Ahh, the Air Regulator. You're right, that's the cold start fast idle. Had it mixed up with the FICD/AAC on the other side that controls idle stability during higher engine loads. Mine is gone too, hah.

    Basically I start the car, and bam she's already at low idle. If it's really cool, you could have some stumbling issues until it warms up a bit.

    Dang that's clean. I need to pick up another plenum to do that with. Mine looks like crap with all the block plates and stuff. Did you just weld things up and then grind them down?
    Prius… because Pretentious wouldn't fit across the back of the car…

    Cheap, Fast, Reliable - pick any two

    My 1986 Turbo Build

  • #14
    It was a spare plenum I had kicking around too, so I wasn't worried if I screwed it up, but it turned out nice. And Yeah, all the nibs and such for attaching wiring harnesses, and even the EGR mount, I cut and ground until it was reasonably smooth, and had the holes welded shut that I wasn't going to use, then ground the welds smooth. Have to watch back in the EGR area, as the material is a little thin around the bend. We'll find out how well it holds boost in a few weeks hah. If all goes well, I'll be getting it gutted.