Pressure Cap Maintenance
7. Clean sealing surfaces on heat exchanger filler
neck with a cloth. Inspect surfaces for any dam-
age or deposits that may prevent cap from seal-
ing properly.
Pressure cap is designed to maintain pressure in
freshwatersectionofclosedcoolingsystemoncethe
engine has attained normal operating temperature.
This raises the boiling point of the coolant, thereby in-
creasing the efficiency of the cooling system. To help
ensure proper operation, cap should be cleaned, in-
spected and pressure tested periodically as follows:
8.
Clean coolant recovery passage in heat ex-
changer filler neck with a wire and blow out with
compressed air.
!
WARNING
a
Allow engine to cool before removing pressure
cap (in next step), as sudden loss of pressure
could cause hot coolant to boil and discharge vi-
olently. 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.
b
1.
2.
Remove pressure cap from heat exchanger.
Wash cap with clean water to remove any depos-
its or debris from sealing surfaces.
72715
3.
Inspect rubber seal on cap for cuts, cracks or oth-
er signs of deterioration. If seal is damaged, cap
MUST BE replaced.
a - Inspect for Damage
b - Clean Coolant Recovery Passages
9.
Reinstall pressure cap, being sure to tighten until
it contacts stops on filler neck.
4.
5.
Inspect coolant recovery gasket for deterioration
and replace if bad.
Check condition of locking tabs on cap. Replace
cap if tabs are bent or cracked.
Seawater Pickup Pump
Maintenance
a
c
Whenever insufficient water flow is suspected, sea-
water pickup pump should be disassembled and in-
spected (by an authorized MerCruiser Dealer).
b
Heat Exchanger Repair
IMPORTANT: Braze with BCUP 2 rod or silver sol-
der. Care must be taken not to melt other joints
during repair.
72714
1.
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.
a - Rubber Seal (cap MUST BE Replaced If Damaged)
b - Gasket (Look For Cracks Under Gasket)
c - Locking Tabs (1 Hidden)
6.
Refer to “Testing Pressure Cap” and test pres-
sure cap as outlined.
2. Nipples and drains that have been broken off the
heat exchanger can be reattached by brazing.
Index
90-823324--2 796
CLOSED COOLING SYSTEMS - 6B-3
| Categories | Mercury MerCruiser Manuals |
|---|---|
| Tags | Mercury MerCruiser 454 CID, Mercury MerCruiser 502 CID |
| Model Year | 1993, 1994, 1995, 1996, 1997 |
| Download File |
|
| Document File Type | |
| Copyright | Attribution Non-commercial |
(4 votes, average: 4.5 out of 5)
Marine readers have rated 1993 1997 Mercury-MerCruiser GM V8 454 CID 7.4L and 502 CID 8.2L Marine Engines Service Manual Number 16 4.5 out of 5.0 based on 4 product reviews. Hugely helpful service manual! Perfect. Thank you!
Manuals are all Important for Technician
This book is invaluable if you do your own repairs. Great book.
Could not find a copy until a search brought me here.
Excellent print.
Thank you