Yanmar Service

When you have it serviced make sure that the impeller is changed, I bought a boat with a smaller Yanmar Engine and according to the service sheet which showed that the engine had been serviced only 50 hours before the sheet said that the Impeller was "serviceable" i.e It did not need changing.
The pump was in a really difficult place to get to and I could not get the impeller out to change it so I asked a Marine Engineer to change it, he virtually had to strip loads of parts off the engine to be able to take the pump off and when he did the impeller was in a very bad state. I reckon it had never been changed due to the difficulty of being able to reach the pump.
It took about 2 1/2 hours to remove the pump to change the impeller.
I imagine that if a Boatyard/Marine engineer is asked for a price to service an engine, when the mecanic who is doing the job realises the additional time it will take to take the pump off the temptation is there to not do it.
This was perhaps just my boat where the inboard diesel was squeezed into a small space,
If you are after a marine engineer in Scotland there are Yanmar Parts dealers up there , why not ring them and ask if they know anyone.
 
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