On Fri, 13 Apr 2018 00:30:57 -0700 (PDT), harry
wrote:

The later bypass hoses were corrugated.

Aftermarket ones were, but not iirc from the factory

Much later (on the A+ introduced on the Metro and Mini) they eliminated the
short bypass hose altogether by using a sandwich plate with a hose spigot
between the head casting and under the themostat elbow connecting to a T on a
radiator hose.

The cylinder head under the thermostat housing was initially blanked with a
screw in plug and later modified so it no longer had any provison for the
screwed in bypass spigot, the water pump also being redesigned to have no bypass
provision
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