Yanmar 10hp single cyl. Water siren sounds after a reeasonably short burst of power.

[Shearwater]

A warm engine running well, revs increased to say 2900/3100 rpm, shutting down to say 1500 rpm again, water overheat siren sounds. After some minutes at lower output,siren shuts off. This, I assume, is not right even though it might appear logical. The engine block is hot, the revs of the water pump are low, so overheating occurs. But this wouldn't happen on a new engine would it? The impeller was replaced (abt) 20 hrs ago, the water inlet filter was cleaned at the same time. So where do I look? Thermostat? Salt encrustation in the tubes? Your experiences would be appreciated.

 

[VicS]

Water injection into exhaust partly blocked

Hoses OK ?

This is directly cooled ?

 

[Appledore]

Hi,

I had a similar occurrence 2 years ago. See here for all the information and pointers:

http://www.ybw.com/forums/showthread.php?368040-Yanmar-1-GM-10-Again

After flushing the engine and replacing the sensor, I've had no further alarm problems - so far. Fingers crossed!

Geoff

 

[agurney]

A warm engine running well, revs increased to say 2900/3100 rpm, shutting down to say 1500 rpm again, water overheat siren sounds. After some minutes at lower output,siren shuts off. This, I assume, is not right even though it might appear logical. The engine block is hot, the revs of the water pump are low, so overheating occurs. But this wouldn't happen on a new engine would it? The impeller was replaced (abt) 20 hrs ago, the water inlet filter was cleaned at the same time. So where do I look? Thermostat? Salt encrustation in the tubes? Your experiences would be appreciated.

Sounds like a dodgy impeller I've experienced a couple of times in the past; if you remove it it will probably look good, but you'll be able to rotate the rubber/nitrile on the metal bush. It may be a 'new' impeller but it might be old or poor quality stock. If you've driven old cars you would recognise the symptoms of a slipping clutch.

 

[bluerm166]

If the water is exhausted freely then why not suspect the thermostat opening at too high a temperature/insufficently ? Take it out and test it as per the workshop manual.

 

[Shearwater]

Sorry, Vic. I shud hv said it is direct cooled. Tks for yr interest. Col.

 

[Shearwater]

Tks for the input. I'll look and if I findant]=ything useful, will revert. Apols that this has been deaklt with inb the past (like most things!) It is just a q. of using the search fac properly.

Col.