Diesel Over Heating

[jhward]

We have a BUKH DV10LSME marine diesel with saildrive in our Cavalier 28. It has been slipped for about 3 days while the rigging was repaired. On starting we had less water than normal coming from the exhaust and after about 10 mins the over heating alarm sounded. We have checked the impellar which looks fine and the inlet pipe and and exhaust appear to be free of obstructions. Does any one have any suggestions? Does this engine have a thermostat and how can you check if there are any obstructions in the pipes or water jacket. Any suggestions on how we can fix this problem would be appreciated.

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[pete]

Hi
I dont know your particular set up but on my boat some times if it has dried out with the sea cock open the water pump has drained and does not allways re prime itself, I open the pipework just above the pump to let the air out and when the impellor is wet the pump re starts. I have just got a new impellor for mine(not fitted it yet) and it seems to be about half a millimeter wider than the old one perhapse due to wear ?
Pete

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[fluffc]

Check the impeller cover for wear. If it is worn down (by the impeller's rotating action), then it may not be able to prime itself. It is often possible to use the other side of the (flat) impeller housing against the impeller if this is the case.

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[jleaworthy]

The impeller may look fine but is it turning? Try turning the engine over whilst the cover plate is removed. Sometimes the bonding between the neoprene of the impeller and the bush in the centre fails.

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[Con_Brio]

The suggestion regarding worn impeller housing squares with my experience. I have a Bukh 20 in my Sadler 29. A few years ago it started overheating. I had to take the inlet hose off the impeller housing and run water into the bilge every time to get a proper flow going before reconnecting. Having checked the impeller and the inlet water filter - both OK - I appealed to Bukh's. The very helpful and knowledgable Mr Pearson there correctly surmised that my boat had spent much of its life on the East Coast with a lot of sand and gritty mud in suspension in the water, which had ground away not the cover but the back of the impeller housing. Replacing the water pump (impeller housing, spindle and washers) proved easier than I feared and cured the problem. NB You have to get the washers correctly positioned back to back on either side of the circlip, or you'll get water coming out of the little holes in the back of the impeller housing.

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[extravert]

The DV10LSME does have a thermostat, it's in a housing above the cylinder head. I had a thermostat fail on mine which lead to the overheat alarm to come on. The simple quick fix for this is to remove the thermostat completely.

The thermostat failing should not reduce the flow of water though. However, has it really reduced? They don't pump a lot through anyway and the cooling water often has steam coming out with it as well, they are well known for this.

I have an old DV10LSME sitting in my garage being broken for spares. If you need any send me a PM.

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