Thread: Exhaust leak on manifold

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I don't know if this is the right section but I have a pretty big exhaust leak from my manifold. I know for a fact its only the one manifold and its every inlet to the manifold

I know the old gaskets didn't come off all the way because the were corroded and baked on to the point that even using a heavy file on the faces to get the most of the old gaskets off then a mill file to smooth it out.

Even then they still didn't come off all the way. It still leaks but is a lot better than previously. Is there any tricks to temporarily seal up inlets so that I can actually run the engine until I completely redo my exhaust this winter next summer?

Find someone with a belt sander long enough to get all 3 ports at same time. take off very little but keep it all flat

run double gaskets ..

I didn't realize i put up the before pictures the old gaskets smoothed silver but didn't go completely flat. I used to have a big belt sander at my parents place but they sold it. I will attempt to double up some gaskets and see if it can get that to work. I am running on a super tight budget lately.

I have had some success in "honing/milling/flattening" metal surfaces using the procedure in this video below. I know that it's not an exhaust manifold but I think you can see the principle that I am talking about. It's basically just gluing the proper grit abrasive to a flat board and using it across "all" surfaces. The hardest part will be keeping the manifold in place while you do this. Good Luck
https://www.youtube.com/watch?v=HyKN52HD6RU

i can try to make that work thanks for that!

or turn the radio up louder ... HA !

Originally Posted by MelloYello

I have had some success in "honing/milling/flattening" metal surfaces using the procedure in this video below. I know that it's not an exhaust manifold but I think you can see the principle that I am talking about. It's basically just gluing the proper grit abrasive to a flat board and using it across "all" surfaces. The hardest part will be keeping the manifold in place while you do this. Good Luck
https://www.youtube.com/watch?v=HyKN52HD6RU

Works great, been doin' that for years. Get your precision straightedge from Goodson....
GOODSON : 24" Precision Straight Edge : PSE-24

Also, particle board is flat, plywood is not.

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Originally Posted by HOSS429

or turn the radio up louder ... HA !

No radio or electronics in my truck other than the heater and instruments. I don't want to crack porcelain or damage the engine to badly just to last long enough to build a new performance engine

I did not watch the u tube except the first few seconds to see where he was going with it----------AND, I need to comment here as anyone could see that probably 99% of those over there were so called haters----------


Todays aluminum over head CAMSHAFT heads cannot just be resurfaced to flatten them because then you will have a camshaft bore that is out of alignment-----they are put in ovens and heated with various supports,etc that will cause them to come back to a flat state-----


And a far as exhaust manifolds to cylinder head---------------this is one of those BASIC mechanic things that has to be done right---maybe good enough doesn't work----------

The heads are good it's just the manifold that's screwed up. I've got another manifold I can use it is very similar and a lot cleaner, but I don't know if it will cause it to breathe differently.

The casting numbers are 3932469 (the bad one) and 3932473 (the good one). the only big difference I can find is the bottom of the good manifold has a block which would push my down pipe about an inch or two down further.

I'll have supporting pictures later tonight.

Originally Posted by Lefcrak

The heads are good it's just the manifold that's screwed up. I've got another manifold I can use it is very similar and a lot cleaner, but I don't know if it will cause it to breathe differently. The casting numbers are 3932469 (the bad one) and 3932473 (the good one). the only big difference I can find is the bottom of the good manifold has a block which would push my down pipe about an inch or two down further. I'll have supporting pictures later tonight.

The video was not necessarily only about re-surfacing a cylinder head, it was a tutorial showing how to re-surface and level parts at home for cheap. When I replied, I did not mean that I have done heads like this, I haven't. But I have used this procedure for leveling other parts in my home garage and it works great. If you tightened your manifold up in a vise and used the procedure shown, you would end up with a perfectly good manifold that would hold gaskets very well. Make your board long enough to be able to stroke the entire length of the 4 ports. I further understand that you probably don't want to buy a precision straightedge, I just included that for the other members of this forum so that they would have a source for it. If you use particle board and cut a band of paper that is normally used on a powered belt sander, you can make this tool for cheap. Here, for instance, is a belt 4" wide by 21 3/4" in length for 3 bucks. Cut it, lay it down on the particle board and use Gorilla glue to secure it.
http://www.mscdirect.com/product/det...gle-PLA+-+Test

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You should install a trash can in your shop to throw the gaskets in clean both head and manifold surfaces good and bolt it back together metal to metal chevys don't use gaskets don't know why the put those in gasket set the just cause problems .......ted

techinspector1 I will definitely get one just so I have the correct tools for my future shop. Ted my shop consists of a driveway exposed to the elements.

the manifolds share a lot of properties but are slightly different from each other.

That 1"+ long piece of metal where the pipe clamps up is called a heat riser, should have a valve inside, unless someone had already removed the plate.

You can ditch it and use shorter studs if you don't need that length. It was used to force the exhaust up and across the lower intake manifold to help warm it.