Engine service - before or after winter boatyard layup?

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Garold

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My 30hp Yanmar engine is due for a service (about 225 hours since last one which was done in Feb).

We are going to have the boat lifted in a few weeks and stored in a boatyard until next spring (in Greece).

I was considering having the service done before we get lifted because then I know that fresh oil is preserving everything. However, my wife reckons we should wait to have it done in the spring when we launch.

Opinions please because I can see the logic of both.

Garold
 
After the season ends and before layup. The information I got on here is that the oil contains more corrosive elements as it get used, so removing and replacing with fresh oil helps preserve the engine over winter. Maybe the corrosive elements are very mild but over more many years add up to unnecessary damage just by changing the oil.
 
If you leave it all winter with combustion acids in the oil there is a risk that you will corrode the bearings. Far better to change it at lift out when the oil will be hot and easy to extract. The fresh oil will not deteriorate while the boat is laid up. I change mine on the morning of lift out before going to the hoist, then run it for a few minutes while flushing fresh water through via the Vetus strainer. All done then for me then, no risk of freezing in Leros.
 
How many hours of engine run time is it before combustion acids start to build up in new oil? Immediate, 1 hour, 3hrs, 10hrs? Just trying to schedule the long list of jobs at lift out, packing up and putting the boat to bed.
 
hoped4 said:
How many hours of engine run time is it before combustion acids start to build up in new oil? Immediate, 1 hour, 3hrs, 10hrs? Just trying to schedule the long list of jobs at lift out, packing up and putting the boat to bed.
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The acids should not in fact "build up " the oil contains additives which neutralise the acids. The concentration of these additives, and hence the ability to neutralise the acids is "defined" by the oil's "total base number" ( TBN ). In theory , provided the oil has not seen more service hours, or been run with a higher sulfur fuel, than intended there should be no problem from corrosion if the oil change is delayed until the following year's fitting out.

However I would still go along with the recommendations to carry out the engine service and oil change before laying up, leaving only the pump impeller change until fitting out time.
 
VicS said:
The acids should not in fact "build up " the oil contains additives which neutralise the acids. The concentration of these additives, and hence the ability to neutralise the acids is "defined" by the oil's "total base number" ( TBN ). In theory , provided the oil has not seen more service hours, or been run with a higher sulfur fuel, than intended there should be no problem from corrosion if the oil change is delayed until the following year's fitting out.

However I would still go along with the recommendations to carry out the engine service and oil change before laying up, leaving only the pump impeller change until fitting out time.
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Do you change the impeller every year :confused:
 
sailorman said:
Do you change the impeller every year :confused:
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Not necessarily. ITYWF that many of the popular engine manufacturers advise checking the impeller annually, or after a specified number of hours, which ever is sooner, and replacing if necessary. I cannot though see the point of putting an old impeller back in having gone to the trouble of removing it although perhaps this is a view that results from the relatively more difficult job of accessing most outboard engine impellers
 
I change the oil and then go for a good motor about before being lifted out. For the impeller on my Bukh engine, I replace it every second year. I have tried getting a third year, but I found that the pump started refusing to prime sometimes. I do take the impeller out over winter, though.
 
I run the engine to get it hot and then change the oil and filter, plus fuel filters and run for a few minutes. I remove the impellor and flex each vane to make sure there are no cracks. If ok it goes back in in the spring. I also carry a couple of new impellors and one with a cut off vane as an emergency spare which I tested and seems to be fine.
 
I change oil after lift out. My sump drains easily, and I also can run the engine out of the sea, using fresh water to the seawater pump. That flushes the engine seawater cooling circuit, warms the oil and then shut down and change out oil filters and impellor.
 
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