intake manifold: splitting / resealing Q's

A6 All/ S6 All
#1

Car’s finally in for a carbon clean @ 115k, and installing the phenolic spacers. My manifold flaps ‘rattle’ @ idle audibly, and I’m discussing with them splitting the manifold and gluing the flaps shut in the “short” position (figuring the low end tq loss would be mitigated by the additional runner length afforded by the phenolic spacers).

They said they prefer not to split the manifold as re-sealing it is a PITA and the one they’d done previous was a disaster.

Any insight here appreciated - tips, suggestions, best practices, secret handshakes, etc.!

Or… do I just leave it and live w/ the clatter? I couldn’t care less honestly - the car drives like a scaleded cat even w/ that ‘flaw’, my only fear tho is ingesting a large flap chunk and muffing up the motor. Or would the plastic bits merely incinerate? My worry is one could jam a valve open - eeeeeeeeeeek! Unfounded???

TIA, gents!.. hopefully soon as mani’s off and shop awaits direction accordingly…

#2

If you want the “short” flap position, just gut/remove the flaps. I don’t think you’d be happy though; there’s a pretty big TQ loss down low. Most of the gains from the “short” runner position are above 4500rpms(ish?)… You want that torque, trust me.

So, epoxy them in the closed position if anything…

re-sealing; I got nothing. There’s several pics on this site of the manifolds open and TBH I don’t recall seeing any sort of silicone or gasket. I’ll have to back through and check, but I think it’s just an interference seal between runners and possible an ORing around the outside.

#3

Thanks.

Right now I’m in the “whatever” flaps position… chaos… flaps everywhere since they’re likely largely disconnected or disintegrated.

So just maintain that via gutting… or… leave as is for fear of re-seal… Bueller?

#4

Only go long runner. If you go short runner for sure or you’ll not be happy. The long runner stays active in most driving until 5000rpm. Now, if you drive over 5000rpm 90% of the time then sure, use the short runner.

If you think the flaps are rattling, take off the intake manifold and look on the inside of the intake with the Y pipe off.

You should be able to look down the tunnel and with the flap motor unbolted, you can move the flap lever by hand. From there, you count the flaps and make sure that all 10 are moving. When you can 100% validate that there might be one or more that are not moving you can then split the intake to fix.

This is what you see JHM doing at 2:08 in this video
https://www.youtube.com/watch?v=WIFddsRcMp4

I would make sure you validate that flaps are broken before you split.

I would never advise you live with the clatter as that clatter is the intake manifold flaps rattling around, and if you wait long enough, those flaps will break off and end in your cylinder heads. So, when you look at the possible issues you might get with trying to reseal Vs leaving it alone you’re much better off spending some extra time resealing the intake then trying to pull intake parts out of your cylinder heads.

Did that make sense? If not, let me know

#5

Words of wisdom. Hope to see a r&d / production IM for these cars in the near future. Luckily when these IM work, they do work well especially in concert with the JHM boltons or so I’m told :smiley:

#6

Thanks for the detailed response. I do spend a fair bit of time >5k WOT… 120+ cruise speeds daily (Mexico)…

I’ll discuss all this w/ my shop and head there later to inspect the flap status.

I’ll report back. So far, on ginormous nastyass mouse nest in the valley where they chewed up my hood liner and firewall material - f’n bastards!

#7

WHAT and no pictures of that… ive seen some legit mouse car nests.

Honestly your intake is probably broken in more than one flap. If you never have had the intake off you never know if pieces are actually stuff in the runners now.

I would def try to pull the intake apart. like CV said your better off trying to seal the intake back up than dealing with what could go wrong if you let it go

#8

I haven’t sent my intake in yet, but I can post pics of it split in half.

The reason they say that they are hard to reseal is because of the runner channels, once I post up a pic you’ll see it, but I can’t see why a “black” silicone engine sealant wouldn’t do the job just fine?

I ended up just buying a new intake, while I know it’s an expensive fix, well worth the investment.

#9

Yes. Keep maint in check and you will be good.