Chip -
More important than what kind of cement you use, you need to stop-drill the
crack. You mention that it grew quickly. Cement MAY goo it over, but it
WILL NOT add any structural rigidity. Although you probably are hesitant to
add any openings to your manifold, you should drill a small (from your
description, 1/16" or maybe even less is probably fine if you get the very
end of the crack. Be sure to drill at the very end - if you drill somewhere
with more crack beyond your drill hole, it'll just keep growing with every
pulse of vibration through the engine. The smooth, round hole stops the
progress of the crack. This works on sheet metal, plastic, etc. as well as
castings. The old Plexiglas windows and aluminum cowlings and baffles on my
airplane are full of stop-drilled cracks that stopped right where I
discovered and drilled them.
- Karl Vacek
'66 TR4A - IRS
'64 Amphicar
'16 Ford T Touring
'46 Piper J-3 Cub
Chip Krout wrote...
> The small hairline crack in the exhaust manifold of the Spit grew very
> quickly last week to a now very visible and noisy crack. One of the
triggers
> was probably fatigue brought on by a missing bolt that secures the exh
> manifold to the lower intake manifold. (I fixed that)
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