Exhaust Manifold Question

[bobc]

Can the exhaust flanges on the stock cast iron exhaust manifold be shaved to remove imperfections in the surface?

Best,

Bob

[peterc]

angle grinder?

[Nissanman]

If you are referring to the surface that mates to the head, yes.

Any competent Automotive machine shop should be able to surface grind the flanges to dead flat for you.

[Bruce Palmer]

Be conscious of the fact that some flanges share studs with the intake and if you remove too much from either will leave the other flange thicker. This can lead to uneven clamping force by the big thick washer on the thin portion of the flange.

[Diseazd]

Bruce is dead on.....you could end up with a leaky exhaust gasket.

[MikeW]

Just how bad are the imperfections? It seems like exhaust gasket sealant would fill them in.

[bobc]

Ok, I'll ask. Exhaust Gasket Sealant? Who makes it and where do I get it. I have Copper Gasket Sealant, but I didn't put it on the gasket. I wouldn't think it would be thick enough to do any good.

The flanges were pretty pitted when I pulled it off. I think it can be shaved and not take off enough to create a problem with the places where the nut holds both the exhaust and intake manifold.

Just an FYI, I'm being a perfectionist. You can't hear the leak and most people wouldn't even see it. If I can't get the manifold shaved, I'll probably go to headers, although I'd like to keep the car bone stock.

Bob

[MikeW]

The copper stuff is what I was thinking of. If the flange is pitted that alone may not be enough to cause an exhaust leak assuming there's flat surface surrounding the pits. I'd be more worried about a long scratch or a crack.

[beandip]

What I have done on both OEM and headers to tru them, is to use a file. I have a couple of files that are about 24'' long and I pass the file over the flanges contacting more than one or two at a time. Then truing them all, mostly they just need to be flat across the whole plane, and only a couple thousands of an inch is removed any way. The gasket will seal any small imperfections . I prefer the gasket sold by Motorsport that they sell for use with there headers. It is thick and seals vary well and I have been able to use on even after removing the manifolds more than one time.

Gary

[bobc]

Thanks Gary, that's a good idea to use their header gasket. I think I'll have the flanges planed while I have the manifold off. Cheap insurance! On the other hand, it's sure nice to have my Z running again!

Bob

Edited January 5, 2009 by bobc