COMET CENTRAL

64 comet straight 6. One of the bolt heads on the exhaust manifold is broken off and my son would like to remove the manifold to replace the bolts. Any chance this thing can be removed without pulling the engine?

You should not have to remove entire engine unless other engine block work is required. To repair broken bolt in the head, you may be able to work in the car on it but a lot easier if the head is removed.
Exh fastener problems are not unique to the small six. Other manifold bolts also may also break off when attempting to remove.


have fun

Old exhaust manifold bolts are the world's worst for breaking. If it snapped near the head of the bolt, soak it with penetrating oil for a few days, warm it up with a propane torch and try to get it out with a heavy set of vice-grips. If it snapped at the head, you'll need room to drill.

EDIT: If you pull the manifold, soak all the bolts as previously mentioned. Be very careful and feel for flex when you try to remove them with a socket or wrench. If it flexs, stop and soak some more or go for the torch. Gently warm around the head.

JT

here's a simple 'kluge' fix by a PO:
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have fun

try to use a 6 point socket,,,and no more extension on the ratchet then you have to use,,,and break loose by hand,,loosen just a tiny bit...flip ratchet and tighten a tad,,flip ratchet and loosen just a tad,,,,repeat method several times,,,don't be stingy with the pent oil...and you may not breake a bolt...heat always helps...good luck pop

I am hoping my change over to exhaust studs and bronze nuts eliminates broken bolt problems in the future my success rate at removing broken ones is not too good the current head had about half of them broken but I left for the machinist to remove when the head work was done and I think he had to drill a couple of those out,IIRC I was able to weld a nut on one that had broke right above the head surface and finally got it backed out, wasn’t fun, and yes the head was up on the bench at the time.
See Ya,
Mike