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Discussion Starter #1 (Edited)
Ok i had and exhaust leak when i first installed ottp header. When i was done and the leak seems to be gone. Im going to drive it more when i have the chance to make sure. But i used The Fel Pro Composite Gasket and a GM donut gasket. Now the problem is that theres a casting edge on the head that doesnt allow the flange to fully seat on the head. I to clearance the flange on the header.





 

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Re: OTTP Header exhaust leak help

I just got done installing the ottp header on my 2.8 and theres a small exhaust leak. New metal gm manifold gasket and fel pro donust gasket. All bolts have been checked and tightened several times. It doesnt have it at idle only when on the throttle. Did this happen to you and after a few heat cycles it sealed ? Which gasket did you use ?
You should have used the thicker composite type Fel-Pro exhaust manifold gasket and the smaller diameter GM donut gasket.

You may also want to check the header flange tubes for cracks and improper tig welding spots.
 

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Discussion Starter #3
Re: OTTP Header exhaust leak help

I ordered the fel pro gasket not knowing it came with one and with a friends reference i used the metal one. Is there a different part number for the smaller donut gasket? I did give it a once over and i could not see any visible cracks. Ill look again when i go to change the gasket out.
 

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Re: OTTP Header exhaust leak help

Check the upper right portion of the block. I had to grind the upper right corner of the flange on my Ottp header because the block had some material there in the corner that Ottp evidently didn't see. It took me a couple times taking the thing on and off and switching gaskets before I noticed it.
 

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Re: OTTP Header exhaust leak help

Basically I had to grind something like a 45 on the upper right of the header.
 

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Discussion Starter #6
Re: OTTP Header exhaust leak help

When you say upper right, do you mean fire wall or power steering pump.
 

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Re: OTTP Header exhaust leak help

The thinner stamped stainless type oem exhaust flange gasket is more suited for the cast iron type manifolds and the stock donuts are smaller in diameter than the Fel-Pro brand. You may want to use a spray bottle with some soapy water around the header during a cold initial start up to pinpoint the exhaust leak.
 

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Discussion Starter #8
Re: OTTP Header exhaust leak help

Alright ill change it out and see what happens. I did notice that the donut didnt fit like the factory one when i pull it off the old manifold. I appreciate the help. Looks like ill be visiting the dealer this week.
 

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Re: OTTP Header exhaust leak help

I mean the upper corner closest to the front of the truck
 

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Re: OTTP Header exhaust leak help

I (and everybody else) originally thought I had a leak when I installed mine. It was the stock tubing right after the header making a ringing sound only under load. You could actually hear it on idle if you were under the truck near the tubing. It's probably the same "pinging" noise people complain about when they gut the pre-cat.
 

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Discussion Starter #11
Re: OTTP Header exhaust leak help

I dont think i could call this noise a ping but sounds like like a small exhaust leak. just air escaping. it sounds like its coming from the flange behind the power steering pump. But yes it gets more noticeable when you rev it and you can just barely hear it at idle. Hopefully this weekend i can get to it and change over the flange gasket and even change the donut to the gm one.
 

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Re: OTTP Header exhaust leak help

Get someone to stuff a rag in the tailpipe while you listen under the hood. If there's a leak you'll find it that way.
 

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Re: OTTP Header exhaust leak help

I know with mine which was for the 3.5 I had to trim the edge of the flange to sit flush on the block.
 

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Discussion Starter #14
Re: OTTP Header exhaust leak help

@Fitzer where did you have to trim ? I used a straight edge to see how flush it was and the edges seemed like they were no more then a piece of paper off from the center.
 

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Re: OTTP Header exhaust leak help

The front edge. The flange went on to a ridge of the block which stopped it from sitting flush. The turbo manifold I got from OTTP needed to be trimmed to. I think it's something about the newer 2.9 and 3.7 flange on the 2.8 and 3.5 engines.
 

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Discussion Starter #16
Re: OTTP Header exhaust leak help

Just to make sure when you say front you mean the front of the truck? how much did you trim off ?
 
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