SERVICE MANUAL NUMBER 26
CLOSED COOLED MODELS
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 every two years 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.”
Pressure Testing System
WARNING
Allow engine to cool before removing pressure cap. 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.
If coolant section of closed cooling system is suspected of leaking or not holding sufficient
pressure, and no visible signs of leakage can be found, perform the following test:
1.
2.
Remove pressure cap from heat exchanger or reservoir.
Clean, inspect and pressure test pressure cap, as outlined under “Testing Pressure
Cap,” to eliminate the possibility that cap is not maintaining proper pressure in system
and is causing coolant to boil over.
3.
4.
Clean inside of filler neck to remove any deposits or debris. Examine lower inside seal-
ing surface for nicks or other damage. Surface must be perfectly smooth to achieve a
good seal between it and rubber seal on cap. Also check locking cams on sides of filler
neck to be sure that they are not bent or damaged. If locking cams are bent or damaged,
pressure cap will not hold the proper pressure.
Adjust coolant level in fresh water section to 1 in. (25 mm) below filler neck.
Index
90-861329--1
MARCH 1999
Page 6B-5
| Categories | Mercury MerCruiser Manuals |
|---|---|
| Tags | Mercury MerCruiser 181 CID |
| Model Year | 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 |
| Download File |
|
| Document File Type | |
| Copyright | Attribution Non-commercial |
(6 votes, average: 5 out of 5)
Marine readers have rated Mercury MerCruiser GM 4 Cylinder 181 cid 3.0L Marine Engines Service Manual Number 26 5.0 out of 5.0 based on 6 product reviews. Thanks for sharing this material. Helps a lot after suffering with bad mechanics. spend too much money and nothing very good
great manual, makes impossible jobs possible. without a manual you can not do the job, a must have.
Great resource. Excellent information provided.
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