T&T: Ford Lehman 120 potential casualty

[Rich Gano]

John notes: Obviously, in Rich's situation the best thing to do would be to
shut down the engine as soon as possible.  But let's say you have a more
insidious situation like mine above.  Would it be best to shut down the
engine (and all related cooling ability) when the alarm activates or maybe
back off the power and if the alarm ceases allow the engine to cool via the
engine cooling system (which is obviously compromised but is doing
something)?  I have been told (by the attending diesel mechanic in my above
scenario) that abruptly shutting down the engine during an overheat may not
necessarily be the best thing to do?

Rich responds:  I have had the situation where an overheat alarm, in this
case the exhaust overheat (NOT the alarm to the sensor immersed in engine
coolant) went off, and I did not shut down the engine because the coolant
thermometer was not registering high temp AND because a visual inspection
indicated no bad things going on.  Slowing the engine for a few minutes
allowed the exhaust heat sensor to cool below the alarm threshold, and the
alarm went off.  So in short, yes, I agree that there are times when you
don't want to shut down completely but allow the engine to idle in an
overheat situation, but you'd better be right!

In the case of my exhaust overheat alarm, I had just added the alarm and the
accompanying electronics and was not sure I had the sensor mounted just
right; so I suspected that the real problem was not excessive heat, and a
glance at the engine heat gauge gave me the initial confidence to proceed by
idling.  Realignment of the sensor solved the issue.

Rich Gano
CALYPSO (GB-42 #295)
Southport, FL