bukh thermostat

[Rhylsailer99]

my engine warning light and buzzer came on bukh dv20 .When i got back i removed the thermostat and checked it , as the water heated up it slowly moved out but is it supposed to go out with a pop.
there was plenty of water coming out of the back so i could only guess the thermostat was not opening to block the bypass pipes.
i will check the water ways this week as i did not have much time as i did not want to get stuck on my boat waiting for the next high tide.

thermostat is just over 12 months old and the engine was de scaled last year can they clog up in just 12 months ?

 

[neilf39]

It will go out slowly as it heats up so sounds like it's working. Have you checked the impeller to see if it has shed a fin or more. If it has you need to find all the bits as they could be blocking part of the flow. Even a small amount, not noticeable from the exhaust flow could cause a problem. Unlikely to have scaled up in a year but does depend how much scale was removed when you last did it.

 

[neil_s]

My DV20 needs descaling every 4-5 years so I don't think you're scaled up yet. Did you keep the old thermostat? Might be worth popping that back in. I have two, both many years old, that get swapped every now and then. They don't 'pop' open when you test them, either.

 

[Malish]

Withdraw the pipe feeding into the cylinder block and check it for blockages especially those parts of the pipe that cannot be easily viewed - rod them out with a bit of rigging wire or similar, I usually find a precipitate hidden away.

 

[VicS]

my engine warning light and buzzer came on bukh dv20 .When i got back i removed the thermostat and checked it , as the water heated up it slowly moved out but is it supposed to go out with a pop.
there was plenty of water coming out of the back so i could only guess the thermostat was not opening to block the bypass pipes.
i will check the water ways this week as i did not have much time as i did not want to get stuck on my boat waiting for the next high tide.

thermostat is just over 12 months old and the engine was de scaled last year can they clog up in just 12 months ?

A thermostat which is only 12 months old should be Ok

It should just start to open at 60C ( for a directly cooled engine) . This temperature is usually marked on the thermostat.
It should then open progressively over a range of 10-15 °. The temperature at which it should be fully open may also be marked on it.

The water flow though the bypass should be restricted as the thermostat opens to allow water to flow through the engine. I'd not expect to see any marked reduction in flow from the exhaust as that happens.