Oil Foams Out Of Pump Fill/Vent Screw; Sterndrive Unit Cannot Be Lowered From Up Position Or Lowers With Jerky Movements; Sterndrive Unit Will Not Stay In Full Up Position For Extended Periods - Mercury BRAVO Service Manual

TROUBLESHOOTING

Oil Foams Out Of Pump Fill/Vent Screw

Contaminated oil.
Oil level low.
Sterndrive Unit Cannot Be Lowered From UP Position Or Lowers With Jerky
Movements
Air in trim system.
Low oil level.
Insufficient IN/DOWN pressure or
shuttle valve stuck.
Trim cylinder(s) binding.
Gimbal housing-to-trim pump hydraulic
hose pinched.
Hoses reversed on one trim cylinder
only.
Drive unit binding in gimbal ring.
Down pressure relief valve (6) has dirt
particles under check ball.

Sterndrive Unit Will Not Stay In Full UP Position For Extended Periods

External leakage.
Pump OUT/UP circuit leaking
internally.
Trim cylinder(s) leaking internally and
pump DOWN circuit leaking internally
(both must be faulty to cause this
problem).
Page 1C-18
Cause
Cause
Cause
SERVICE MANUAL NUMBER 28
Special Instructions
Flush system with clean oil refill pump
and bleed trim system.
Check for cause of low oil level and
correct. Add oil to pump and bleed
system.
Special Instructions
Check for cause of entry. Fill and
bleed trim system.
Add oil.
Test. If shuttle 1 is stuck, replace
pump adaptor. (Refer to SECTION 5A) If
pressure is low, replace adaptor or
attempt to repair by replacing the
following items:
D IN/DOWN pressure relief valve
Check for cause of binding. Repair or
replace as necessary.
Replace hose 8.
Reconnect hoses correctly.
Check for cause of binding and
replace.
Replace with a new valve kit.
Special Instructions
Check for cause and correct. Add oil to
pump and bleed trim system.
Test. (Refer to SECTION 5A) Replace
adaptor 2 or attempt to repair by
replacing the following:
D Thermal relief valve
D Poppet valve seals
Rebuild cylinders 5 Repair or
replace adaptor 2 as required.
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4
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90-863160 MAY 2000