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Discussion Starter #1
Alright guys-

I just got the Cleveland powered up and it runs excellent, aside from some nasty exhaust leaks. It has headers on it right now, with Mr. Gasket gaskets. I've double-checked and all of the bolts have been properly tightened. Is it possible that the headers have been warped? If so, what can I do about it? A friend suggested putting another set of gaskets on it (a total of two sets) to help seal it up better. Any help or advice is much appreciated! Thanks.


Michael
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Yes its possiable for the header flanges to warp. One thing you can do is to use a new gasket and put a bead of red high temp silicone around each port on the header flange. Let it set up some before you bolt em on and it will fix the leak. Downside is the red stuff oozing out around the header is not to good to look at. mm
 

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Old Trick..we would soak the gaskets in water for a few hour or over nite so they would swell up, then when you torque the bolts down, it will make a good seal. the heat from the exhaust will dry them out. this is with using the paper type gasket.
 

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Bowl, (and others)...

An even older trick is to go with no header gasket at all. Think about it for a minute. Did your cast iron exhaust manifolds have a gasket? Did they leak? I got tired of blowing out header gaskets on my 4V clevelands. The gaskets don't have much sealing area on the 4V ports.

With a good quality set of headers, you can see if the sealing area of the headers is smooth and even. If not, get out your grinder and go nuts! Either grind all of the 'bead' off and seal with the flat flange, or just grind enough of the bead off to make sure you have a flat surface to work with. Also, you might want to cut each port apart from the one-piece flange (if your headers are so equipped) to avoid any warpage and to ensure a flat mating surface for each port.

I will resort to using a small schmear of hi-temp silicone if all else fails, but I'll never use another paper/asbestos 'gasket' again!
 

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Discussion Starter #5
A real noggin' scratcher

Well, I think I found the real exhaust leak this time, except it's a little bit of a puzzler; it's leaking out of bolt holes ( I guess ) on the heads! I put my hands up to 'em and hot exhaust gas is pumping outta them. There's one in the front and one in the back of each head ( four total). Now, I've never rebuilt a Cleveland before this, so I'm not sure what this all means. Any help is very much appreciated!


Michael
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Sounds like you have 73 or later heads with the EGR passages. The bolt holes on the front and back of the head are also used as a drilling point for the passage for the EGR provision. Just thread in a couple of bolts with a good sealer on them and go from there. I'll have to go out to the garage and check my AlphaCats stock 73 heads to be sure, but I think that's right.

Later 429/460s (and for that matter smogger smallblocks) also have this passage but on them it is used for the thermactor (air pump) passage with holes in each exhaust port for injecting clean air into the exhaust stream so the catalytic converter works right and burns of any unburned hydrocarbons. On those engines they have a small freeze plug type thing there to block off the passage on the ends of the heads at one end. The other end has that infernal air tube bolted to them at the back of the head.
 

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Yep definitely sounds like the egr holes in the back of the heads are open. Just one small curious thing what year heads are you using because my 73 351W heads didn't have those holes.
 

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Discussion Starter #8
The engine's out of a 1973 Mustang and has 2bbl heads on it. I assumed that these holes were part of emissions control, but the engine didn't come with a pump or any of the thermactor system. Maybe the guy that sold it to me took 'em off... Anywho, the holes don't have any threads in them so I've gotta figure out how to get some in there. Hopefully I won't have to take the headers off :angryfi: because that's a chore when it's sitting under the hood of my '68. Thanks fellas!



Michael
 
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