VanguardTM Twin-Cylinder OHV Liquid-Cooled Engine Section 2 - Troubleshooting
11. Disconnect outlet hose from tester before removing from spark plug hole.
a. Coolant level must be no more than 1 in. (.25 mm) below bottom of filler neck.
12. Repeat test for other cylinder. The variation between the two cylinders should be less than 20%. If the difference is greater than 20%, check the cylinder with the lower reading. Possible Causes for Poor Compression: 1. Loose cylinder head bolts 2. Blown head gasket 3. Burned valves, valve seats and/or loose valve seats 4. Insufficient tappet clearance 5. Warped cylinder head 6. Warped valve stems 7. Worn bore and/or rings 8. Broken connecting rods
CHECKING COOLING SYSTEM
Fig. 25 2. Install cooling system pressure tester on radiator and pressurize system to 15 psi (1.03 Bar). NOTE: System must maintain pressure during
test. 3. Check the following for any signs of leaking. a. Hoses and connections (also check hoses for excessive bulging) b. Radiator c. Water pump d. Telltale hole in crankcase cover e. Intake manifold and by-pass hose f. Cylinder block and cylinder head
NOTE: If coolant is evident at the telltale hole in the crankcase cover, Fig. 26, this is an indication that the water pump seal in the crankcase cover is leaking, which may cause coolant to enter the crankcase and contaminate the oil. Severe engine damage could occur. Pressure Testing Cooling System 1. Remove radiator cap and make sure coolant is at correct level, Fig. 25.
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