I've always seen foam on the bottom of the intake manifolds.

I just bought a brand new LS6 intake, new in box from GM, but it didn't have the foam.

Is this necessary? What does it do (dampen vibration or such)? Can I use standard 3M foam tape? If not, is there a p/n for it?

Thanks in advance.

 

I believe the foam is for the knock senors. When I bought my intake gasket kit it came with the foam strips. Hope this helps.

 

The foam does a few things, helps limit dust, but more importantly it cuts down on noise. They should come with your new gasket kit.

 

I bought GM part number 88894339, which is supposed to come with the intake, intake manifold seal, manifold gasket, throttle body seal, map sensor and map sensor seal.

I take it the foam would be the intake manifold seal? I have a p/n of 12560251. Does that sound right to anyone? Would I need qty 1 or 2 of the seal, if indeed that is really the part.

Alternatively, could I just take the foam of the LS1 intake?

 

thats funny bc i did an ls6 swap for a buddy and ground off all the ribs and foam and now he is getting knock sensor codes being thrown.

 

Because of vibration.

 

Usually it is because of one of 2 things. Either leaving the foam off the front has allowed water to get in the valley cover with the knock sensors and has contaminated them, or the knock sensor harness got pinched between the intake and the heads (common occurence). Normally the fix when you put on a new intake is to check the integrity of the knock sensors, get rid of any water in the hole, then when you put them back in the valley cover, and before you put the intake down on, then lay a U shaped barrier of silicone that starts on the left side of the cover and curves around the front and ends on the right side, basically making the "U" open to the back. this will help to seal between the valley plate and the intake, and make a barrier to keep the water channeling to the rear and out of the engine. normally when this is done, the front foam seal is put on and the rear is left off.

just my .02 tho.

 

Thanks for the info.

FWIW, the p/n I listed earlier is the correct one. I'm picking up 2 this afternoon from the dealership. About $10.

John, I like your idea with the RTV around the sensors. I'm assuming the rear is left open for drainage.

 

correct. some people put RTV all around the rubber grommet that goes in the hole, but i do not like that idea very much. it needs to vent.

 

Very good info here. It's my car that 01ssreda4 was talking about. Since the swap I have P0332 throwing for KS #2. Concerning the pinching of the harness, how exactly does that work? I mean, wiring doesn't really act like a "hose pipe" as far as pinching is concerned, does it?

 

I have seen the harness pinched between the intake and the head and it cut the wire, grounding the sensors and throwing all sorts of codes. it was not easy to see either, as that black wrap around them makes them hard to see

 

Ahh okie I see!

Another detail about my #2 KS code...it's intermittent. It'll come on for 2 or 3 days, then go off for about a day. Thoughts?

 

^^^^that intake swap all was well before. we sealed the knock sensor covers completely and ground all fins/foam off 100%. now the code keeps popping up. so the conclusion is we need to pull the covers and look for moisture around the sensors and possibly put some new foam in as well???

 

as long as the orig foam is not falling to pieces you should be ok. just double check it all IMHO. cant hurt

 

^^^the car was an ls1 to ls6 swap. i ground all foam off the donor ls6 intake. there is no more foam.

 

I wish I had put some foam between my fast and the valley during the swap. It makes a **** ton of noise now.

 

Can I ask what GM in charging for a new LS6 Intake?

 

what kind of noise??? im not understanding this for some reason.

 

http://www.sdparts.com/product/88894...LSEngines.aspx

looks like we have it for $470 plus shipping...

 

Every noise that touches the intake is louder. I doubt it's as bad with a ls6 as the fast but I can actually hear what sounds like the valves closing echo through the intake at idle. And all those "diesel truck" noises the lsx engine is notorious for are louder. I also have a "sucking" sound like a vacuum leak at high idle (no throttle, in gear around 1k rpm).

The foam may or may not help quiet any of these.