Intake Manifold Leak Help
02-11-2018, 05:26 PM
#1
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Intake Manifold Leak Help Engine is an '05 LQ4 with factory intake. The factory 317 heads were milled about .030" and using a LS9 head gasket (~.051). I'm now having trouble getting my intake manifold to seal. The vacuum leak is very small, not enough to throw a code, but enough to watch the O2 sensors read rich when propane is introduced around the intake gasket area. Also have high positive fuel trims at idle and large positive trims on decel.
The bolts all line up perfectly and had no issues while installing it. Torqued in sequence and in 2 steps.
I've tried a new gasket, now using the aluminum framed Fel Pros (MS98016T).
Should I try removing the sleeve from around the bolt?
The bolts are torquing up fine, but I'm thinking maybe they are bottomed out on the sleeve or the rubber grommet is worn out and isn't clamping the manifold with as much pressure as it should. I also considered the manifold hitting the valley cover bolts, but with the truck intakes I can't see it being an issue.
Before I get flamed, yes Ice searched and read every thread there is about intake manifold sealing. The problem is folks aren't great about following up when they solve their problem. I couldn't find any fixes that fit my situation. Wanted to ask before I tear everything apart again.
I was told by many sources milling the intake face of the heads wasn't necessary until you go over .040". Should i have had the faces milled? Yes. Did I? Nope. Pulling heads is a last resort at this point.
Would greatly appreciate any help or insight.
The bolts all line up perfectly and had no issues while installing it. Torqued in sequence and in 2 steps.
I've tried a new gasket, now using the aluminum framed Fel Pros (MS98016T).
Should I try removing the sleeve from around the bolt?
The bolts are torquing up fine, but I'm thinking maybe they are bottomed out on the sleeve or the rubber grommet is worn out and isn't clamping the manifold with as much pressure as it should. I also considered the manifold hitting the valley cover bolts, but with the truck intakes I can't see it being an issue.
Before I get flamed, yes Ice searched and read every thread there is about intake manifold sealing. The problem is folks aren't great about following up when they solve their problem. I couldn't find any fixes that fit my situation. Wanted to ask before I tear everything apart again.
I was told by many sources milling the intake face of the heads wasn't necessary until you go over .040". Should i have had the faces milled? Yes. Did I? Nope. Pulling heads is a last resort at this point.
Would greatly appreciate any help or insight.
02-11-2018, 10:05 PM
#2
I would try another intake manifold before I bothered with pulling the heads. You can get the LM7 type intakes cheap here in Houston. I have seen people selling them for as little as $25 and the average is around $50.
Different intake, with new gaskets, and then see if the leak is gone. I don't know how much truth there is to it but I've heard the manifolds can warp. NO gasket is going to fix a warped intake. Please note I have no personal experience with a warped intake, but I have read posts where people are talking about it.
Different intake, with new gaskets, and then see if the leak is gone. I don't know how much truth there is to it but I've heard the manifolds can warp. NO gasket is going to fix a warped intake. Please note I have no personal experience with a warped intake, but I have read posts where people are talking about it.
02-21-2018, 07:23 PM
#3
Did you figure it out?
These gentlemen seem to indicate its ok to remove the dowels.
https://ls1tech.com/forums/generatio...-problems.html
These gentlemen seem to indicate its ok to remove the dowels.
https://ls1tech.com/forums/generatio...-problems.html
Last edited by 95wannabe; 02-22-2018 at 05:09 AM.
02-21-2018, 07:49 PM
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I did figure it out, warped intake. I took it off and put a straight edge on it and the cylinder where the propane would spike my fuel trims was recessed and twisted. No idea how it happened. I put it back on and cranked the torque down to 120 in lbs and it seems to be holding now. Time will tell if it holds up. I did have the intake ported by Colorado speed. maybe weakened it.