SERVICE MANUAL NUMBER 23
CLOSED COOLED (FRESH WATER) MODELS
8.
Clean coolant recovery passage in heat exchanger filler neck with a wire and blow out
with compressed air.
a
b
72715
a - Inspect For Damage
b - Clean Coolant Recovery Passages
9.
Reinstall pressure cap, being sure to tighten until it contacts stops on filler neck.
Seawater Pickup Pump Maintenance
Whenever insufficient water flow is suspected, seawater pickup pump should be disas-
sembled and inspected by an authorized MerCruiser Dealer.
Heat Exchanger Repair
IMPORTANT: Braze with BCUP 2 rod or silver solder. Care must be taken not to melt
other joints during repair.
1.
2.
Internal leaks can be repaired by brazing shut the ends of the leaking tube. This is only
a temporary fix because usually another tube will start leaking after a short period of time
and this also causes a reduction in cooling capacity. Do not close more than three tubes.
Nipples and drains that have been broken off the heat exchanger can be reattached by
brazing.
Testing Closed Cooling System
Testing Coolant for Alkalinity
WARNING
Allow engine to cool before removing pressure cap as sudden loss of pressure
could cause hot coolant to boil and discharge violently. After engine has cooled,
turn cap 1/4 turn to allow any pressure to escape slowly, then push down and turn
cap all the way off.
Coolant in fresh water section should be changed per Maintenance Schedule recommenda-
tions and should be checked for alkalinity at least once between change intervals. To check
coolant for alkalinity, proceed as follows:
1.
2.
Obtain pink litmus paper from a local supplier (drug store, pet shop, etc.).
Remove pressure cap from heat exchanger and insert one end of litmus paper into cool-
ant.
3.
4.
If pink litmus paper turns blue, coolant is alkaline and need not be replaced.
If pink litmus paper remains pink, coolant is not alkaline and MUST BE REPLACED,
as explained under “Changing Coolant.”
90-861326--1
MARCH 1999
Page 6B-5
| Categories | Mercury MerCruiser Manuals |
|---|---|
| Tags | Mercury MerCruiser 454 CID, Mercury MerCruiser 502 CID |
| Model Year | 1998, 1999, 2000, 2001 |
| Download File |
|
| Document File Type | |
| Copyright | Attribution Non-commercial |
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