1978 Johnson 175, 200, 235 HP Outboard Service Manual, Page 19Get this manual
TROUBLE CHECK CHART (CONT) TROUBLE POSSIBLE CAUSE EOVERHEATING POWER HEADSee Section Thermostats dam aged Thermo cover or gaskets damaged Pressure control valve damaged Exhaust cover gaskets leaking Head gaskets leaking (warped head) (water in cylinders) Water intakes obstructed Pump housing air bleed restricted Water passages obstructed Pump plate not sealing (bottom) Pump impeller damaged Pump housing worn Pump housing distorted (motor run out of water) Pump housing cover seal worn (driveshaft grooved) Water tube grommet damaged FLOWER UNITSee Section Propeller hub slipping Bent or worn propellerconverging ring missing Bent gear housing or exhaust housing Incorrect propeller ASPARK PLUGSSee Section Cover or inner terminal damaged (terminal point out of H.Tlead) Faulty leads or crossed leads Loose spark plugs (low torque) Defective spark plugs (cracked insulator) Incorrect spark plugs BIGNITIONSee Section Incorrect timing Loose wiring Coils damaged Arcing around ignition coils Loose connections to sensor coils, charge coils, ignition coils, or on power pack ground lead Leads grounding out on sensor coils, charge coils, ignition coils, or key switch Sensor coils Charge coils Power packs ArCing in key switch AMOTOR ADJUSTMENTS Incorrect Propeller Mounts looseloss of rubber bond Incorre ct trim angle Remote controls incorrectly adjusted BCAVITATION OR VENTILATION Protruding hull attachments Keel too long Bent propeller (vibration) Transom too high Overheating CBOAT Improper load distribution Marine growth on bottom Added weight (water absorption) Hook in bottom Catamaran (single engine)venturi effect 3LOSS OF POWER (Providing