OM-C3 11/21
41
Service and Maintenance - 500 Hour
SP 20. Remove, Inspect and Clean Engine Heat
Exchanger Core
IMPORTANT: Initially remove and inspect the engine
heat exchanger core at 250 hour or three month service
interval on a new engine. Then, remove and clean at every
500 hour or 12 month interval thereafter.
1. Close sea cocks and drain the sea water system.
2. Open drain cock on cylinder block and drain
approximately two gallons of engine coolant into a clean
container. Close drain cock.
3. Loosen hose clamp (A, below) and remove hose from
rear end cap (B, below).
4. Remove two end cap mounting cap screws and remove
end cap (C, below) with heat exchanger core (D, below)
from rear of engine.
Heat exchanger - hose clamp (A), end cap (B)
Heat exchanger disassembled - end cap (C), exchanger core
(D)
NOTE: The heat exchanger core may be removed from
housing when either end cap is removed. It is strongly
recommended that both end caps be removed for cleaning
when cleaning the heat exchanger core.
5. Remove remaining end cap from water manifold/heat
exchanger housing. Remove end cap from heat exchanger
core.
6. Thoroughly clean all buildup from both end caps and
inspect zinc plug in each. Replace plugs as needed. (See
INSPECT AND REPLACE ZINC PLUGS in 250 Hour
Section.)
7. Use a 4.76 mm (3/16 in.) diameter brass rod to clean
out any buildup in each heat exchanger tube. Run the rod
the entire length of each tube to push debris out (below).
8. Flush the heat exchanger tubes with clean water,
making sure all tubes are cleared of debris. Clean (with
brass rod) and flush heat exchanger again if necessary to
remove any remaining debris from tubes.
If you suspect that your heat exchanger core is defective,
have your authorized servicing dealer or engine
distributor pressure test for leaks. Replace heat exchanger
core as required.
9. Remove and thoroughly clean water manifold/heat
exchanger housing if needed.
