Intake manifold not sitting flush during reinstall, warped?

[ribsandwhiskey]

I have a 2003 Tahoe with the 5.3 flex fuel motor and has 198k miles on it. I replaced the knock sensors under the intake manifold and everything has gone relatively smooth until I began to put everything back together. I'm trying to put the intake manifold back in and it will not sit down flush on both sides. I can get one side down but it leaves about a 1/4" gap on the other side. I played with for over an hour trying to get it in but something doesn't seem right. I guess my question is, is there a trick to this or is it possible that the manifold is warped that bad.

 

I'm not a mechanic but I know my way around my truck pretty good but this is about to whip be being that its going on three day now that I've been working on this.

 

Also I replace intake gaskets and cleaned all surfaces. Any info or help would be greatly appreciated.

[txab]

Are you tightening the bolts in the correct sequence? You don't just tighten one side then the other.

 

You could very well have a warped manifold. It will need to be replaced if it is

 

 

 

 

 

44 inch lbs. first pass

 

89 inch lbs. final pass

 

 

 

 

[ribsandwhiskey]

Hey thanks for the reply. Yeah I know there is a tightening sequence but I can even get one side down close enough for the threads to catch to even begin tightening them. I get the passenger side flush and the driver side has a gap. I can then get the driver side down and the passenger side has a gap.

 

Should the gaskets on both sides be sitting flush before I begin the tightening sequence. I've talked to three mechanics including one at the local Chevy dealership and all three said they have never seen nor heard of one being warped to the point that it wouldn't bolt down, which is making me think its something I'm not doing.

[ribsandwhiskey]

I over looked your comment about it being warped. That's the only thing I can come up with. Do you know what would cause it to warp so badly if that is the case.

[txab]

I've replaced one for being warped. Are you sure there are no obstructions keeping the manifold from laying down properly?

[ribsandwhiskey]

I got the manifold back in and everything plugged back in and connected. I got the fuel line pressurized and now when I crank it it turns over for a split second and violently shuts off. Any ideas?

[ribsandwhiskey]

Now it Acts like its going to crank and just shuts off. Not so violent any more

[Prokopchuk_9]

1/4" is alot. Most I've seen for warpage on some manifolds and heads is like .030". Something else goin on there.

[nickvrebel]

most likely it's the gaskets. What gaskets did you use? I've seen where some Fel-Pro (typically top notch brand) didn't fit, OEM fit just fine. The little locator feet on the bottom of the gasket were just slightly off. I'm guessing it's not on there right and it's not sealing....

 

another thing is to make sure you have the fuel lines connected well, the initial attempt to start may have just been the fuel in the rail, check the fuel pressure at the shrader valve on the rail.