<VV> Engine Cooling

Dave Keillor dkeillor at tconcepts.com
Wed May 23 10:58:53 EDT 2012


It's clear that GM knew that the high performance engines (turbo and 140)
 had a tendency to overheat.  They discovered this, no doubt, during
pre-production testing.  The logical thing to have done would have been to
improve the cooling, but that would have cost time and money.  Instead,
they took the cheap and easy way out, and simply increase the actuation
temperature of the snap switch from 525F to 575F for those engines (and AC
cars).  Out of sight, out of mind.  If 575F is a safe operating limit for
the high performance and AC cars (it isn't!), why isn't it safe for the
other cars?  It costs money to use two different part numbers.

The use of a 575F snap switch is, in my opinion, the single biggest reason
for the high rate of dropped seats in the 140 engines.  You can run your
140 at 570F (which, in my opinion, is quite overheated) for long periods
and for multiple cycles and never know it.  The turbos at least had a CHT
gauge.  525F is unreasonably high, but 575F is ridiculously high.  Clearly,
GM knew that the high performance engines ran hotter, but felt that setting
the over-temperature indication just short of meltdown was a satisfactory
solution.

-- 
Dave Keillor


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