[DML] Re: Rusty Exhaust Manifold Studs

["David Teitelbaum" <jtrealty@xxxxxxxxxxx>]

I forgot to mention that in most exhaust applications I also see the
stud is "special" in that the end that goes into the head (the
casting) is usually a course or "standard" thread and the part
sticking out that holds the exhaust manifold on is a fine thread as
are the nuts. This seems to be the best combination as fine threads
don't have as much strength in a casting but you can get more torque
on a fine thread and if they loosen you don't lose as much clamping
force as on a course thread. In general you don't remove the studs
unless you are machining the heads or you break a stud. The best
exhaust manifold gaskets I see are the metal embossed type, they seem
to hold up the best but eventually they rust, rot.
David Teitelbaum
vin 10757


--- In dmcnews@xxxxxxxxxxxxxxx, "Stephen Card" <stephen@xxxx> wrote:
> The po of my car ran then let the car with an exhaust leak on the 
> drivers side. I am doing battle with the manifold now.  The last two 
> studs over the engine mount did in fact break and were the cause of 
> the leak. When I removed the manifold they were well rusted around, 
> as well as between the two halves. Of course they broke just a 
> little recessed of the face of the block.
> Upon inspecting the face of the manifold the last port where the 
> studs broke were not in line with the other two faces but recessed 
> about 1/16". I suspect the extra tension on the manifold caused the 
> studs to break. The face was also badly pitted. Needless to say I 
> had the face of the manifold ground to bring the faces all in line 
> and eliminate most of the pitting and hopefully the tension.
> Stephen
> Vin 3601
> 
> "Typically it is not the fastener that fails, the gasket blows 
> out........ the longer you drive with an exhaust leak the more 
> trouble you will have with the fasteners and you may have to have 
> the exhaust manifold "planed" or ground flat so it will make good 
> contact with the cylinder head."




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