RE: [ihc] Weekend Chores?

[Tom Harais <THarais@xxxxxxxxx>]

Pete:

#3) that's the heat riser valve.  it's supposed to be closed when cold,
helping to force exhaust gases through a passage in the intake manifold,
underneath the plenum to heat the incoming air/fuel charge and back out
through the exhaust manifold on the other side.  There is a bimetallic
spring on the outside that is supposed to open a damper on the inside, when
the engine warms up.

If it's not moving, you can hit it with some penetrating oil and try and
flop it back and forth with your fingers.  This worked for me.

BUT, in most cases, the internal damper has long since disintegrated due to
corrosive effects of the exhaust stream it sits in as well as heat so there
is no real function anyway.

Tom H., '76 Traveler