V10 5.2 FSI Y plenum assembly - read before you mess with it

Having just replaced Y plenum with new one, and taking it off and putting back on multiple of times I thought i would write a fair warning to everyone, who will either take the manifold off, replace throttle body gaskets etc.

  1. Audi manual states that bolts, that hold Y plenum down to the intake manifold itself should be torqued to 9Nm. This is bullshit, as OEM bolts are aluminum (they have to be - if they are steel they will corrode the threads in the intake manifold getting them stripped), and they break at 7.3 Nm. In my expirience 6.5 Nm is totally fine.
  2. Throttle bodies should be torqued to 9 Nm according to Audi. In my opinion this is too much as well. My unit is new, and I dit torque it to 9Nm, however the next time I will do 8, as it is max I was comfortable doing. I think that getting older unit to 9Nm might crack the thing.
  3. Throttle bodies bolts - I have bought 8 OEM new bolts, and 2 of 8 are just a little bit bent, or the thread is cut in a wrong way - hard to tell. Also all of them have their heads offset just a little bit from the bolt core center. I would highly recommend trying every single bolt first with screwing them in with just your fingers - they should go to the end no issue. If you feel it gets locked just a little than don’t use that bolt.


  1. Torque for bolts holding Y plenum to the manifold should be 6,5 Nm
  2. Torque for the throttle bodies bolts should be 8Nm
  3. Check every throttle body bolt first. It should go all the way in the Y plenum effortlessly.

Hope this helps someone in the future.

Great advice. To be honest on many of these bolts and several others. I do a Tq to feel. So I don’t use a TQ wrench. I tighten till I feel it’s snug then start with 1/4 turns after that until I feel the right amount of force has been used. As you said with some bolts you tend to feel like it’s very easy to over tighten them and instinct is one important tool to utilize.

I agree!
I have recently worked on my intake/plenum assembly and one bolt broke in the manifold.
Very good advice!

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Torqued a Mercedes gearbox as factory spec once. The whole block cracked. Will not do that again.
Thanks or the tip!

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