Anyone ever have this???

[jheiv]

I took off my plenum the other day, I replace the wet/bad FPR... my 5th cylinder intake port is black.  Its the only one on the plenum and its covered with this flat black powder.  I was wondering if it might be a valvetrain problem with my intake valve not closing completely.  Does this sound to be right?

Also, a local machine shop is ready to charge me 130 per head to get them cleaned, resurfaced, valve grinding and new head gaskets... is this a good deal?

Thanks, I really appreciate it.
Any ideas welcome here.

[mfewtrail]

The intake port for cylinder 5 is right where the Exhaust Gas Recirculation Valve(EGR) injects small amounts of exhaust back into the intake for emissions purposes.  So the black build-up is likely just carbon build up, you might want to take a look at where the EGR connects to the plenum and see if the hole is partially blocked by carbon buildup.  If it is, use a good cleaner to help break up the carbon and then wipe it out. 8)

[jheiv]

it's actually in the front bay of the engine-- 2,4,6 are in the back... well at least that is the way the lower intake has them stamped...

[mfewtrail]

it's actually in the front bay of the engine-- 2,4,6 are in the back... well at least that is the way the lower intake has them stamped...

1, 3, 5 are on the back bank(firewall), 2,4,6 are on the front bank.

So you're saying the black buildup is actually on the FRONT of the motor or were you just trying to say that you thought cylinder 5 was on the front bank? Shit, I've edited this too many times..lol

[jheiv]

ok i just checked again-- and im positive that my lower intake is stamped with 1 3 5 in the front... with 5 being nearest the breather and nearest the oil fill cap--- well regardless what number it is (5) haha, there is a real thick carbon buildup in the lower intake and continues into the plenum... it is only on that one port.  i am wondering if anyone is thinking its a bad intake valve thats not closing.

im thinking this for two reasons,

1) theres no compression on that cylinder... thats the only one w/o compression
2) how would anything go into the intake manifold during the intake stroke?  that just doenst seem possible-- the only way it makes sense to me is if the intake valve gets stuck-- it would account for the compression loss and for the suit in the port

... any ideas ...

[maddux31]

I've had my intakes off numerous times on the different TGP's I've had and never seen black carbon buildup in just one port.  Not to say that my car is the standard for judging such things but just my 2cents.  I believe mfewtrail is right about the #5 on the upper intake being the one for the egr.  Make sure the machine shop is reputable and make sure you DO NOT use aftermarket head gaskets unless they are the original thickness.  Fel-pro does not carry a gasket for our cars that is as thick as the GM that I know of.  Original Compressed thickness on ours is .0072 I believe.  Fel-pro is .005something.  Not much difference but i have had one fail miserably after about 600 miles.  Your heads should not need to be resurfaced unless you have overheated your car badly., milling the heads too much will affect your compression which is not a good thing with forced induction.  My car went to the red line on temp guage three times and my heads were still within .002 afterwards.  Aluminum is a lot stronger than a lot of us think.  The important things with aluminum heads are the (1.)flat and clean surfaces of head and block, (2.)proper torquing and sealing of the (NEW) head bolts when they are installed, (3.)correct thickness of gaskets.  If any of these criteria are not met the job has a great potential to fail.

[jheiv]

ok not to get distracted-- but i PROMISE you that cylinder 5 is marked with a 5 on the lower intake manifold-- it is a moot point though because im just asking how carbon soot can get back into my intake

thanks

[god910]

I was equally confused jheiv, and what you are not taking into concideration is that where it is stamped....   That is the runner, and it runs ACROSS the engine to the corresponding cylinder on the opposite side.  Threw me through a loop the first time as well.  Look more closely, you will see what I am talking about.

[maddux31]

openings (ports) on the intake manifolds go into the heads on an angle, so the ports on the front of the intakes actually go to the back head and vice versa.  That is where this confusion is coming from I believe.  Dale

[jheiv]

:oops:

i trust you... haha and that may lend less credibility to the rest of my post-- but im still curious how i can get black soot in my intake manifolds... any ideas

[god910]

AND, to answer your question, that is not a bad price, but like was mentioned, don't resurface your head unless nec.  Most machine shops around here charge around $100-$125 for a valve job (2 heads), clean and mag, ~$60, resurface ~$50, and I don't know about the head gaskets, but I don't think that $260 is bad for a set of heads.  If someone else thinks that rediculous lemme know.  I'll shop around some more.

[mfewtrail]

So, in actuality you have absolutely "no" compression on cylinder #6.  I would be willing to bet that you're right on the stuck valve, either that or you have a burnt valve.  How many miles are on this motor? Has it been run hard? A few different things can be possible causes of a burnt valve, a stuck valve is probably going to occur from buildup on the valve stem from everything I've read.  I would imagine if the valve is stuck/burnt, it's going to allow suit into the intakes.  I'm no expert by any means so it could be some other problem as well.  I'm taking an engine rebuilding class at the moment and just happened to be covering cylinder heads/valves this week. :wink:

[jheiv]

97k... ill be taking the heads off by the end of the week and getting them cleaned and looked at-- im hoping it is my valve and not a piston ring-- i dont really feel like overhauling the whole block right now