Hi all,
I have a set of the merged tube CAT headers. I had been warned by a list
member that these headers sometimes have leaks and I was cautioned that I
should pressure test the headers before having them ceramic coated. This
warning was only from one of many users of these headers that I had talked
to so I discounted this warning. Last week, visible inspection revealed a
pin hole leak where the header flange is welded to the collector. I
repaired this with my MIG welder and decided not to tempt fate and heed the
lone warning and pressure test.
Sometimes maybe you shouldn't look for trouble.
These headers have slip joints where the primary tubes meet the merged
collector. These joints are welded on the CAT headers where possible. If
you have ever seen these headers you will have noted that the welds at these
joints do not go all the way around the tubes, in fact it looks like it
would be impossible to do so. Someone with a lot of skill might be able to
weld these joints from the inside. That wouldn't be me.
Anyway, yes these headers leak a lot at the unwelded portion of the slip
joints I have tried to describe. This was verified by the pressure testing.
Is this bad?
I think this type of header would always leak at this area by the nature of
the design. Welding of the complete outer circumference of primary tubes at
the slip joints does not appear possible. Welding the joints from the
inside seems unlikely. Of course I don't know nearly as much about headers
and welding as I would like to so quite possibly I'm wrong about this.
Can you folks with experience with these headers in particular and the
merged tube design in general offer any insight?
Frank
B9471116
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