DIY: Blocking Air Injection holes on 99-00 D16Y8 Intake Manifolds

[bumpstick]

So you bought a Y8 intake manifold and you wound up with air injection? Now you want to plug those holes but don’t know how? Follow the simple steps in this write-up and in about an hour, and for less than $20, you can plug your air injection holes, without JB Weld, Devcon, a trip to a welder, or a nasty vacuum leak.

After gathering parts, I wound up with two intake manifolds for my Y7/Y8 mini-me. One was a 96-98 Auto that I couldn’t use because it had no holes for a 2-wire IACV. The other was a 99-00 Manual but obviously, it had air injection holes. I decided rather than drilling the Auto manifold, I would plug the holes in the Manual manifold. I researched but found no helpful information. I decided not to use JB Weld, as this manifold will see boost and I can’t afford to have a JB Weld plug get sucked into my motor. I also decided not to have the manifold welded because I got a quote of $50, more than I spent on the manifold itself.

Okay, here they are, the dreaded air injection holes:
http://i3.photobucket.com/albums/y100/slammedb5/air%20injection%20bypass/DSC00302.jpg
And the nasty looking plug on the top of the flange:
http://i3.photobucket.com/albums/y100/slammedb5/air%20injection%20bypass/DSC00303.jpg
Notice how the holes open up into the injector ports. The hole has a depth of around 7mm, so in order to keep the injectors sealed, you’ll need a plug that is shorter than 7mm:
http://i3.photobucket.com/albums/y100/slammedb5/air%20injection%20bypass/DSC00305.jpg
Here you can see how thick the flange is:
http://i3.photobucket.com/albums/y100/slammedb5/air%20injection%20bypass/DSC00306.jpg
So I decided to pull the injection tube out of the top of the flange, and as luck would have, it snapped off:
http://i3.photobucket.com/albums/y100/slammedb5/air%20injection%20bypass/DSC00307.jpg

[bumpstick]

So I filed it down flat:
http://i3.photobucket.com/albums/y100/slammedb5/air%20injection%20bypass/DSC00318.jpg
Then drilled out the remaining length of tube with a Uni-Bit:
http://i3.photobucket.com/albums/y100/slammedb5/air%20injection%20bypass/DSC00319.jpg
And smoothed off the top of the hole:
http://i3.photobucket.com/albums/y100/slammedb5/air%20injection%20bypass/DSC00321.jpg
Now on to the parts. I got everything here from Lowe’s for under $17. 3/8th inch 16 NC Tap that came with a 5/16th inch drill bit, 10/32nd inch NF Tap that came with a #21 drill bit, 2 3/8th inch by 3/8th inch socket head screws, and 4 10/32nd inch by 1/4th inch socket head screws:
http://i3.photobucket.com/albums/y100/slammedb5/air%20injection%20bypass/DSC00308.jpg
http://i3.photobucket.com/albums/y100/slammedb5/air%20injection%20bypass/DSC00309.jpg
And some threadlocker from Harbor Freight for $1.99:
http://i3.photobucket.com/albums/y100/slammedb5/air%20injection%20bypass/DSC00313.jpg

[bumpstick]

Okay so know that I had all my parts, it was time to start the drilling and tapping. Use the #21 drill bit in an electric drill to enlarge the four holes on the head side of the flange:
http://i3.photobucket.com/albums/y100/slammedb5/air%20injection%20bypass/DSC00311.jpg
I switched my drill to its lowest speed and tapped the four holes that I had just drilled out:
http://i3.photobucket.com/albums/y100/slammedb5/air%20injection%20bypass/DSC00312.jpg
I made sure to clean the tapped holes out with a blast of Brake Cleaner, to get all the metal shavings out of the hole:
http://i3.photobucket.com/albums/y100/slammedb5/air%20injection%20bypass/DSC00317.jpg
Then I tapped the larger holes, on the head side of the flange and on the top of the flange:
http://i3.photobucket.com/albums/y100/slammedb5/air%20injection%20bypass/DSC00322.jpg
When I finished those holes, I cleaned them out with Brake Cleaner. Then I took out my socket head screws and put threadlocker on them:
http://i3.photobucket.com/albums/y100/slammedb5/air%20injection%20bypass/DSC00314.jpg

[bumpstick]

After a liberal coat of threadlocker, I installed the screws into my freshly tapped holes with a T Handled Allen Wrench:
http://i3.photobucket.com/albums/y100/slammedb5/air%20injection%20bypass/DSC00315.jpg
I screwed them in until they were flush, then torqued them down an extra half turn so that the top of the screw head sat below the level of the flange surface:
http://i3.photobucket.com/albums/y100/slammedb5/air%20injection%20bypass/DSC00316.jpg
I made sure the screws wouldn’t extend too far into the injector ports and possibly cause a leak due to a bad seal:
http://i3.photobucket.com/albums/y100/slammedb5/air%20injection%20bypass/DSC00320.jpg
I did the same for the two bigger holes as well. I made sure to put a screw in the head side hole first, to make sure I could sink it below the surface of the flange. I checked all of my screws with a straight edge to make sure they were good to go:
http://i3.photobucket.com/albums/y100/slammedb5/air%20injection%20bypass/DSC00323.jpg
http://i3.photobucket.com/albums/y100/slammedb5/air%20injection%20bypass/DSC00324.jpg
And that is it. It took about an hour, give or take. Let the threadlocker set up overnight, then enjoy your leak free Y8 manifold.

[deftones444]

awesome write up dude.

[ceyazzie]

nice... good DIY

[EJ2]

very nice diy.

[Dead Bird]

ohhellnoyouguysdidn't

[Colten79]

^^^lawlzz

[Meat_Lovers_Pizza]

woah!