[Alberg30] Fw: Cooling System

[George Dinwiddie]

Brian,

Overheating problems on raw-water-cooled Atomic 4's are very common,
and due to any (or several) of a multitude of problems.  I had an
intermitten problem several years ago that took me forever to track
down.  It finally turned out to be loose flakes of rust in the exhaust
manifold that would sometimes block the water flow and sometimes not.

Since there are so many different causes of overheating, I think
it's best to try to divide the problem space into several areas.

I think that sedimentation in the block will generally cause a
gradual rise in max temperature, not a sudden change, unless the
sedimentation has gotten to the point it's blocking the water
flow.

Is the water flow reduced when the temperature rises?  If not,
I'd suspect the bypass arrangement.  If the thermostat can't
shut off the bypass flow, the engine will overheat.  You can
test this by restricting the bypass hose (the one entering the 
thermostat housing from the waterpump side) with a pair of 
vice grips.  If this cools the engine down, the thermostat
or thermostat housing is faulty, or possibly the water input
to the block is plugged.

If the waterflow is reduced, you have to figure out why.
Either the pump is not pumping efficiently or the flow is
blocked somewhere along the way.  You can disconnect the hose
that runs from the block to the manifold to see how much
water is coming out there.  It's hard to judge, however,
as the pump can't tolerate much backpressure, and a weakened
pump (impeller that's lost its spring or too thick a gasket)
_can_ pump plenty of water against no pressure.  With a cold
engine, you can disconnect and check the flow at various
points.  Be careful not to let the water back up the exhaust
into the cylinders.  Intermittent blockages are always
difficult.

Let us know what you find.

 - George

-- 
 ----------------------------------------------------------------------
  George Dinwiddie                             gdinwiddie at alberg30.org
  The gods do not deduct from man's allotted span those hours spent in
  sailing.                                    http://www.Alberg30.org/
 ----------------------------------------------------------------------


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