Mercury 150 EFI Service Manual page 405

COOLING
2.5 Litre V-6 Water Flow Diagram 2002 Models
8
10
6
7
11
9
4
3 2
1
5
17
16 58063
14
12
15
1. Water Inlet
2. Water Pump
3. Wall of Water – If water level height is insufficient, water pump may draw in air resulting in an overheated engine.
4. Water Tube
5. Main Water Feed to Powerhead from Water Tube
13
6. Water by-pass prevents air/steam pockets at top of powerhead
7. Cylinder Head Cover – Removed from head for illustration, normally part of head casting.
8. Thermostat (2) 143 F (61.7 C) – If stuck closed, engine will overheat at low speed. If stuck open, engine will not warm up at idle speed.
9. Poppet Valve – Controls water flow at high RPM. 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.
10. Primary water discharge into driveshaft housing.
11. 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.
7
12. Water Pressure Sensor
13. Check Valve for powerhead flush
14. Water passing through thermostats dump into adaptor plate, then discharges down the exhaust.
15. Tell-Tale Outlet
16. Excess water from wall of of water around exhaust bucket exits around anodes.
17. Water exiting exhaust discharge.
8
90-883728 JULY 2001 Page 4B-7