possible vacuum leak from intake??

**jmatt07** · 08-20-2009, 04:51 PM

i bought a bbk intake and put in on my 98 ss when i was doing h/c/i swap. i reused the old gaskets bc they looked ok and i didnt get the ls6 coolant lines. it seemed like the intake fit on pretty good but i know the directions said it should sit flush on the heads before tightening down the bolts well it didnt sit perfectly flush but i figured once we tightened it down it would be ok. well i have been having this studdering problem with the car for a while now but it didnt do it for the first month after i did swap....it did have a high idle that i tightened intake more and it fixed but im wondering now if it has a vacuum leak from the manifold making it studder? u guys think this is possible?

**sunsetorangess** · 08-21-2009, 11:47 AM

Yepp it is very possible, never re-use old gaskets unless you absolutly have to. Did you have it tunned after the head/cam swap? Im guessing the idle is irratic? Did you check the intake to ensure it wasnt warped?
J

**jmatt07** · 08-21-2009, 07:12 PM

right now i just have mail order tune done...tryin to make sure everything is right for the dynotune. when i first did swap idle was high and irratic but i tightened bolts down and it helped some but now the car studders and stumlbles and someone else on here had that problem and found out it was a vacuum leak so im thinkin thats what my problem is as well.

**Cutlass** · 08-22-2009, 03:51 AM

yeah those coolant lines could be in the way of the intake sitting all the way down. I had to grind down the fins on the bottom of my LS6 intake for it to fit over the stock LS1 coolant lines. But it still didn't fit perfectly flat.

**leez28** · 08-22-2009, 04:54 AM

you have to replace coolant line for sure ,easy to get from the dealer, i have a wieand intake and had to replace mines ,it cost 15.00

**Firebirdjones** · 08-22-2009, 07:56 AM

You said you tightened it down some more. Those things are only supposed to be torqued to something like 70 inch lbs. Not very much at all.

I never reuse gaskets on something like that. No reason not to use the LS6 coolant lines and block offs. It's cheap. And it saves headaches,,,, like this.

**ntimid8r7** · 08-22-2009, 08:22 AM

$25 could have saved you from the headache of taking it off again. It's a big pain in the ass to begin with! Hope you get it figured out.

**jmatt07** · 08-22-2009, 02:03 PM

anybody have a write up for intake swap?

**Cutlass** · 08-22-2009, 02:43 PM

http://www.ls1howto.com/index.php?article=5

**jmatt07** · 08-22-2009, 05:25 PM

Thank you for the link sir.

my ss is a 98 and ive heard that the knock sensors on them are a problem. you guys dont think that they could possibly be causing any trouble do you? its not throwing any other codes other than for the 2 o2 sensors. I just thought id ask since i will be in there and could replace them.....i dont really have the money for them but if its something that could be causing the studdering then i might have to find the money. thanks

**Firebirdjones** · 08-23-2009, 09:15 AM

The only complaint I ever hear about the 98 knock sensors is alot of false knock.

**0rion** · 08-23-2009, 09:28 PM

go to thunder racing and get the ls6 pipe and plugs. Those bolts are only tightened to like 7 ft/lbs. If you strip those bolts out trying to crank that intake down you're going to have worse problems than you have now.

**Firebirdjones** · 08-24-2009, 06:09 AM

Orion is right on the money. Those bolts are very tiny (skinny) it wouldn't take much to pull the threads out of the heads, and the intakes are only plastic anyway,,,hence the reason for the very low torque setting.

Orion mentioned Thunder Racing, which is where I got my LS6 coolant pipe and plugs as well. Awesome people to deal with. They even called me back on the phone to tell me I didn't need some of the stuff I had ordered and asked why I ordered it. After we realized they were right and I didn't need it they gave me a refund. All this happened before they even shipped the parts. Not many business' do that for ya. I'd use them again for sure. Classy business in my opinion.

**NoscamaroSS** · 08-24-2009, 09:19 AM

The bbk intake will fit perfectly fine with the 98's coolant lines. You are supposed to remove the clips that holds the wires for the knock sensor though. Did you replace the back passenger side valley cover bolt? If not, then theres your problem.

**jmatt07** · 08-24-2009, 10:42 AM

well crap...i already ordered the coolant pipes and plugs. since i have the bbk intake and its not plastic do i need to tighten the bolts down more?? ya i changed that bolt on the passenger side and the clips. i think i might hvae found the vacuum leak tho.....i took the intake off and the bolts that hold that plate on the bottom of the intake...2 of them were completely out and laying on the valley pan and like 4 more of them were very loose. i could have swore i tightened them all up b4 i put the intake on.....anyway i hope that was my problem.

**Firebirdjones** · 08-24-2009, 10:52 AM

I'd stick with the manufacture torque setting regardless of intake material.
That is set in place more for the bolt itself.

**jmatt07** · 08-24-2009, 12:11 PM

alrighty then. I actually have another question. i took the bbk intake off and i looked inside the ports and noticed that when they made the intake there is like chunks of aluminum sticking up off the surface inside some of the ports....i was wondering if it would be alright to take a grinder and knock those chunks of metal off bc im sure they cause a restriction and also since im in there would it hurt to open up the ports of the intake itself a bit? to port the intake myself?

**NoscamaroSS** · 08-24-2009, 12:34 PM

The bolts on the plate was going to be my next suggestion, I would suggest you to use locktite on them they fall out all the time. It wont hurt a thing to clean up the casting makrs in the runners, just make sure you clean it out good so no shavings are left in the intake.