Engine Overheat; Engine Knocks; Engine Backfires Through Carburetor - Robin EH09D Service Manual

10-4 ENGINE OVERHEATS
(1) Crankcase oil level low. Add oil immediately.
(2) Spark timing incorrect.
(3) Low grade gasoline is used, or engine is overloaded.
(4) Cooling air circulation restricted.
(5) Cooling air path misdirected causing loss of cooling efficiency.
(6) Cylinder head cooling fins clogged up with dirt.
(7) Engine operated in an enclosed space without sufficient cooling air.
(8) Exhaust gas discharge restricted, or carbon deposits in the combustion chamber.
(9) Engine running on low-octane gasoline detonates due to heavy load at low speed.

10-5 ENGINE KNOCKS

(1) Poor quality gasoline.
(2) Engine operating under heavy load at low speed.
(3) Carbon or lead deposits in the cylinder head.
(4) Spark timing incorrect.
(5) Loose connecting rod bearing due to wear.
(6) Loose piston pin due to wear.
(7) See causes of engine overheat.

10-6 ENGINE BACKFIRES THROUGH CARBURETOR

(1) Water or dirt in gasoline, or low-grade gasoline.
(2) Intake valve stuck.
(3) Valves overheated, or hot carbon particles in the combustion chamber.
(4) Engine cold.
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