Mariner Mercury 105/140 JET, Service Manual

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2.5 Litre V-6 Water Flow Diagram 2000 Models
1. Cylinder Head Cover – Removed from head for illustration, normally part of head casting.
2. Thermostat (2) 143
°
F (61.7
°
C) – If stuck closed, engine will over heat at low speed. If stuck open, engine will
not warm up at idle speed.
3. Check Valve for powerhead flush.
4. Poppet Valve – Controls water flow at high RPM.
NOTE: If poppet valve is stuck open at low RPM, the engine will not reach proper operating temperature (run cold) and
will run rough at idle.
5. Primary Water Discharge into Driveshaft Housing.
6. Water passing through thermostats dump into the adaptor plate, then discharges down the exhaust.
7. Water Dump Holes for Exhaust Cooling (2 each) 1/8 in. (3.175 mm) – if holes are plugged, tuner pipe will melt
and bearing carrier prop shaft seals will be damaged.
8. Tell-Tale Outlet
9. Water Tube
10. Wall of Water – If water level height is insufficient, water pump may draw in air resulting in an overheated engine.
11. Excess water from wall of water around exhaust bucket exits around anodes.
12. Water Inlet
13. Water exiting exhaust discharge.
90-824052R3 JUNE 2002
POWERHEAD - 4B-5