Drivers side header donut gasket not sealing

[bambbrose]

This is for my daily truck, having trouble getting it to seal up and was looking for advice.

2004 GMC 1500
Stock 5.3L

Hit a stump while offroading on the cat/y-pipe, whatever you want to call it.

Now it is leaking from that stupid donut gasket seal.

I've pulled off the entire Cat/y-pipe and replaced the donuts on both sides, torqued to oem specs, and still leaked. I then CRANKED on the three nuts, until my craftsman deep socket broke! and it's still leaking from between the flanges on the drivers side.

Just to clarify, this is the gasket between the oem cast manifold, and the oem Cat/y-pipe.

On this particular vehicle, the drivers side is a small crush ring, and the passenger side is a large traditional donut gasket.

Any advice on how to seal this up for good? It is a daily, and I can't be tearing it down often. I need a permanent solution. I have confirmed that the leak is coming from between the flanges, and that neither flange is cracked.

Thanks

[usmcchevy]

I'm going to guess you did something like this to the flange. You can buy a used flange or there are new available, check ebay. Ether way the new flange will need to be welded on. Good luck.

[spudz]

what he said... we see it at work all the time on 4x4s with that stupid sealing ring. Either replace y-pipe or pull the y and get a new flange... It has to be perfect because its not clockable.