Marshall Booth wrote:
The same thing as thermostat seat erosion occurs when the thermostat
doesn't open fully. The thermostat is supposed to open 8+ mm (at 94 deg
C in a 123) but often as they age (or overheat - even only once), they
only open 6-7 mm and that has the same effect as the seat eroding (the
bypass doesn't close fully).
Marshall
I'd like to elaborat. There is NO active cooling other than coolant flow
and changing flow through the radiator until the engine temp reaches
about 100 degrees. The fans should NOT engage (except as responding to
refrigerant temp or pressure in the AC system ) in normal city driving
(with the AC off) and coolant temp should NOT exceed 86-95 deg C. It
should not be much below 85 deg either or you will be wasting fuel.
The thermostat is NOT designed to facilitate cooling! It's purpose is to
PREVENT cooling until temperature reach 85-87 degrees and then to slowly
allow more and more cooling to occur as engine temperature rises until
coolant temps reach 94-102 deg C (depending on the particular engine).
ONLY after the air temp blowing across the viscous fan exceeds about 85
deg C., (corresponds to coolant temp of about 100 deg. C., but different
on different engines and under different driving conditions) or coolant
temp exceeds 100-105 deg C. to trigger the aux fans (when they were
configured for engine cooling) do the fans engage and contribute to
cooling by increasing airflow across the radiator.
None of the '80s and '90s diesels had inadequate cooling systems!! If
there was a cooling problem, it resulted from SOMETHING not working as
it should and not inadequate cooling capacity design. Most cooling
system failures resulted because of improper/inadequate maintenance (use
of incorrect coolant, coolant not changed on schedule or use of
excessively hard water and failure to properly flush the system once
that was determined).
There were also the trap oxidizer issues with '85-'87 3 liter diesels
and the excessive heat load those devices created as they plugged up
from insufficient highway driving. Once the traps were removed, almost
all the overheating issues (except from cracked heads) vanished and the
OM603 engine run at very modest temps even at high speeds (UNLESS the
viscous clutch becomes lazy or aux fan operation somehow fails).
Marshall
--
Marshall Booth (who doesn't respond to unsigned questions)
"der Dieseling Doktor" [EMAIL PROTECTED]
'87 300TD 182Kmi, '85 190D 2.0 161Kmi, '87 190D 2.5 turbo 237kmi, '84
190D 2.2 229Kmi (retired)
