Missing gasket

[tuononero]

Hi guys.
It's been a while since last time i posted on this board.
Life kept me away from this car but now i'm back on it.

I've had an o2 problem since my stepdaughter overheated and cracked the heads.
So basically since i partially rebuilt the engine.

New heads, new gasket...

Since the error says something like insufficient treshold, my investigation lead me to believe there's an exhaust leak.
The sound of the car confirms that thought. So i started removing the whole system hoping to find holes, cracks, corrosion signs or anything obvious.

Even though every component looks in good shape i have found something that looks pretty weird to my eyes.

The cross over pipe that connects the two headers only has a gasket on one end (the one that goes to the header on the back of the engine).
The part that goes on the front header has no gasket at all.

I went on http://www.gmpartsdirect.com/auto-p...ne/exhaust-system-cat/exhaust-components-scat trying to find a part number or a good illustration of what i need and the picture looks kinda confused...
Btw the only gasket that it shows me is the 1647558.

When i go on ebay looking for that number it shows me a gasket that looks identical to the one i have for the part that goes on the back of the pipe.

Also the part of the header that couples with the pipe looks shaped perfectly to fit on top of the pipe (even without gasket), and it looks not possible to me that the seal mentioned above (donut shaped) could ever match the two surfaces.

What really confuses me tho is that when i go on rockauto looking for a cross over pipe it shows me this one that has two gaskets apparently IDENTICAL:

http://www.rockauto.com/en/catalog/...32256,exhaust+&+emission,crossover+pipe,16090



Now could anybody please tell me what the deal is with this cross over pipe?

Thanks

 

[Scottydoggs]

if its really loud the flex in the down pipe might be shot. its right at the flange where it moves.

 

[tuononero]

No it's not loud and the flex looks to be in very good conditions.

 

[Scottydoggs]

prety sure the cross over just presses together, id try some hi heat rtv and clamp it back on evenly.

we are dealing with stock manifolds right?

 

[tuononero]

Yes it's all stock.
So are you telling me there is no gasket from the factory?

 

[Scottydoggs]

dont think so, ive only ripped it off my car to install headers, but i dont recall a dounut or gasket there, its two flange clamps that bolt together. maybe loosen the manifold bolts some, then clamp the cross over pipe on both ends, then tighten the manifold bolts down for good.

i hope you re used the stock metal manifold gaskets, the after market ones suck.

 

[GTPpower]

There is no gasket on the front, just the back as you have found.

 

[tuononero]

I see, another 10 points to the engineers for the amazing job.

Ok thank you so much