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intake manifold knocking???

19K views 31 replies 18 participants last post by  87LC2 
#1 ·
so i took my 06 gto to the track on friday for the first time ever. the car ran great but the next morning i was giving my buddy a jump cuz his battery died and i noticed a knocking noise comming from my intake manifold. i shut down the car and looked thru my t/b and didnt see any thing inside so im asuming that its comming from one of the chambers up top. it gets more progressive with with more gas too. i know its comming from the manifold because i can feel something hitting the top of it while the car is ideling. any one have any idea what could be causing this?
 
#9 ·
Do you hear it with the hood closed. Is in a solid Knocking sound, or more of a ticking? It is common for the valve train on these cars to sound like a sewing machine. Mine makes an audible ticking sound, and it sounds like it is coming from the intake when the car is running with the hood open. Have you noticed it being down on power or anything strange? Also, the injectors are mounted in the intake, and can make a ticking noise.
 
#11 ·
Does sound like a rod bearing. Your intake manifold is hollow and it will act like a echo chamber for internal noises
 
#13 ·
i had the same sound ur talking about and it was indeed a spun rod bearing. i had 15k miles. as stated above pull the valve covers check for little stuff first then time to pull the motor and either rebuild or buy a new shortblock.
 
#18 ·
thats what i am thinking. because its a definitive feeling when you put your hand on the manifold. the only thing is that it gets progressivly faster with more throttle. im going to pull the valve covers off and i will get back with everyone and let you know what i come up with.
 
#15 ·
I've owned two goats and both make a little tick tick sound that I've never been able to run down. sounds like valve train noise. but damn, if yours has started knocking and you can hear and feel it in the manifold, that's not normal.
 
#16 ·
Maybe a bent or broken pushrod. Did you over rev or mis-shift the car at the track?
 
#19 ·
it is deffinatly making a knocking noise. it isnt a ticking. its much louder and it sounds like its comming from the top end. i crawled under the car cuz i figured that if it was a bearing i would be able to hear it better from under it but that wasnt the case.
 
#20 ·
got a stethoscope ? Or, put your ear to a long screwdriver.

I'd guess collapsed lifter, bent pushrod. Easy to check. I'd start at the loudest point.

These aluminum block & head, with a plastic manifold make noises travel. I had a noise I'd swear was a roller rocker but ended up being a lifter. Noise travelling all the way up.
 
#21 ·
I love how people just assume spun rod bearing in every situation. Bottom line is if his car is basically stock, he takes care of it (regular oil changes, checks oil level), the odds of a spun rod bearing after 36k are low. Its probably something up top like a lifter or pushrod as stated by a couple of members. I would take a video and post it as well.
 
#22 ·
There's also unknowns, too. Was he low on oil ? Did he add 1 quart ? I do, at the track. Did he bounce it off the limiter, miss a shift ?
 
#23 ·
I had this problem after installing a ported intake, i made the mistake for lack of a better word and reused the old gaskets which were only 38000 miles old, i dont know if one got pinched on the plastic lip when i torqued the intake down or what happen but one of the gaskets ripped in half and air was shooting through the gap making a solid knocking or ticking noise comming from the intake valley, i too figured it was time for a rebuild but i decided to pull the intake first because that was the last thing i had off and discovered the bad intake gasket. Replaced all the gaskets and there was the problem.
 
#25 ·
how loud was it? im just wondering bc i think i had a very similar problem to the op and my knock was very loud and increased with revs. i checked everything and pulled the heads and there was wonderful debris in the oil and everything it was a joy.
 
#24 ·
Also, after 14000 miles on pacesetter headers my header gasket on the passenger side went bad and i was knocking horribly not making a hiss as they usually do, i figured the motor was shot and parked it, a few days later i was getting ready to disasemble and restarted the engine to check things out, after moving all around the car and using a long screwdriver to my ear the only thing i found was it was comming from the passenger side rear cylinder, for some reason i decided to stick my hand back there and it instantly nearly burned my finger. I shut the engine off and let it cool for about 30 minutes, started it up and put my hand back there and found that the header gasked was blow out in the back and the air was shooting out the hole in the gasket making a knock, not a hiss, or a tick. This may sound stupid but i had a mechanic look at it briefly before i parked it and he too said time for a rebuild. Ive never heard a sound like that come from a bad header gasket, but if it cracks or blows out a certian way air can make funny noises when being shot out of the engine that fast. Just another thing to check before you start tearing into things only to find nothing.
 
#26 ·
I have a tick as well that is similiar in every way except that it goes away apon increasing revs above 2500k. Sounds like its coming from the passenger side (cyl 6 or 8)
I pulled the heads and had them pressure tested. I also checked the push rods, springs, valves, piston faces, rockers, and replaced the lifters with new Ls7's. Cleaned and inspected my cometic gaskets. Sprayed them with copper coat, and buttoned everything back up. At initial start up there is no ticking. But once the car reaches operation temp and i rev it... theres the tick. If i continue to rev it, eventually the tick becomes consistant without reving. . I've also diconnected each coil pack (unloading each cylinder) to see if the noise will go away of get quieter. Nothing changed.

THought!? Could this be an exhaust leak
 
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