Service Manual

Coolant Thermostat ISB, ISBe and QSB (Common Rail [...]
Page 8-14 Section 8 - Cooling System - Group 08
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Remove
NOTE: This stepblock does not apply to QSB5.9 marine
engines with keel cooling.
Remove the water outlet connection capscrews.
Remove the water outlet connection.
Remove the thermostat.
On QSB5.9 marine engines with keel cooling, remove the
water inlet connection capscrews and the water inlet
connection from the thermostat housing used with keel
cooling.
Clean and Inspect for Reuse
CAUTION
Do not let any debris fall into the thermostat cavity
when cleaning the gasket surfaces. Damage to the
cooling system and engine can occur.
Clean the mating surfaces with a gasket scraper and a
clean cloth.
Inspect the thermostat for cracks, tears, damage, missing
soft seat.
Remove and discard the gasket.