Hot water low oil pressure

[RobP]

Doing a lock flight Hekla does not like sitting on tick
over for any length of time, and the temp. creeps up from
the normal 70-80C to 90C+, oil pressure drops from 1.5bar
to under 1, the oil warning light starts flashing, and
tick-over revs drop to a point where the engine is
'hunting' and sometimes stalls.

Pop the clutch button out and leave the engine on fast
tickover (1,000 rpm) and she is fine.

Engine is a Lister CanalStar LPW4A

 

[nicknorman]

Always hard to tell "by remote control" but I would suggest the water pump is below par, maybe the impeller has lost some blades or (if they are aluminium) they have dissolved due to not having /changing the antifreeze. What is the temperature of the water exiting the skin tank? Don't burn yourself! If it is not that hot, whilst the feed to the skin tank is exceedingly hot, then a water pump issue is likely, although I suppose an air lock in the skin tank is also possible.

[PhilR]

It is probably also worth checking that the thermostat is opening fully.

 

If the cooling system is in good order, It would be more normal to get the opposite symptoms after a long period of idling in neutral. (i.e lower coolant temperature and higher oil pressure).