What may cause cylinder cooling water temperature to become abnormally high?
Cylinder (Jacket) cooling water temperature rises in the following cases:
1. Insufficient heat removal.
The Jacket cooler may become dirty or secondary cooling medium (SW) flow reduced. Check the system line up for closed valves. Check SW re-circulation (if installed). Clean the FW cooler.
2. Restricted cylinder cooling water flow.
May be caused by circulating pump fault or air/vapor lock in the system. Check the pump performance. Release air/vapor accumulated. The air lock accumulation usually happens after the engine overhaul if cooling system not vented properly.
3. Malfunctioning of the temperature control valve fitted on the water cooling system.
Open and inspect (temperature control) thermostatic valve.
4. Engine (or individual cylinder) overloaded.
Temperature rises because designed heat removal capacity of cooling system is exceeded. Reduce the load. Balance load between cylinders.
5. Crack in the cylinder liner or cylinder head.
Accompanied with increased pressure of cooling water, exhaust gas emission from the expansion tank. Stop the engine ASAP and investigate the cause. Replace liner/cylinder head.
