overheat problem

[captaindan]

Hi
I have a issue with my port side engine that was running hot (KAD42S) Now I had volvo penta have a look at the engines and they said the bottom of boat needed cleaning as it was blocking intake for water. We did this and then took it out and the engine was running hotter than the starboard engine. At around 90 degrees and once at a ccuisine pace would drop a degree or two. Now we drove for some 360 nautical miles along the coast but kept to 18 to 20 knots to keep the engine from overheating. I took the boat out yesterday and the engine overheated in minutes too 250 degrees. We switched the engine off let it cool down started engine and sounded fine . We then noticed the ignition lights had stayed on won't go off and the Rev counter was not working. Drove for a few minutes engine overheats very fast . Swirly chef engine off and drove back to port engine sounds fine. Baffled to say the least does any one have any suggestions or advice

Kindest regards

Danny

 

[macnorton]

Are you sure the engine is getting hot and it is not a mis reading gauge?

 

[Divemaster1]

Fast overheating can be caused by cooling circulation pump failure (pump that circulates the coolant, not the raw water pump).

Have you lost coolant ?

Other than that I'd start with the simple things:

1) Seawater strainer lid (can pull air)
2) Coolant hoses
3) Raw water pump (Impellor)
4) If damaged impellor, you may have to hunt for rubber bits in the heat exchanger
5) Then you have the heat exchanger etc ...

 

[Viscount]

Slipping belts? On mine the belts drive the alternator which provides the signal to the rev counter (and the battery light indicating low voltage) and also drive the fresh water pump.