Oil Changes

A follow on from our saildrive problems

https://www.myhanse.com/saildrive-problems_topic15362.html

When the engineer came on our 2003 Hanse 341 to listen to the saildrive problem, he also said he did not like the sound of the engine.  Running the engine in his workshop and then examining it, he found the problem was that minimal oil had been getting to the top of the engine and that all the components of the rocker system showed wear of some form or other.  Thankfully, this engineer has wide experience of working on large diesel engines around the world and has the skills and philosophy of repairing items, rather than throwing away a system and replacing it with new.  He therefore had a number of items machined/skimmed up and rebuilt the engine.  The engine now starts and runs much better.

The Problem

I do not know what happened in the first 6 years of the yacht’s life, but I have always done an annual oil change.   However, having to drain the oil out of the engine through the dipstick hole results in there always being a residue of dirty oil left in the engine.  20 years of build-up of dirt had basically blocked the oil galleries feeding to the top of the engine.

Recommendation

Our engineer’s advice is that we should always follow a policy which he uses of flushing the engine each oil change.  So, the warm oil should be extracted, preferably straight after a sail, when all the oil is mixed up.  (It can be useful to weigh the quantity of oil extracted, to know how much to refill finally) Then sufficient new oil should be put into the engine to fill just past the minimum oil level mark and the engine run under load for 20 mins or so.  Then drain the oil, change the filter and refill with new oil to the normal oil level.

The cost of the extra oil is less than the cost of an engine overhaul.

 

History is littered with engine failure due to poor oil changing and stretched service intervals. In recent times engines have become more reliable and service intervals have been greatly increased. The majority of people think that this is due to improved design and manufacturing quality. This indeed is a part of the reason, but the single biggest improvement in reliability and increased service intervals has been achieved through significant improvements in oils. Engine components and bearings are still made from the same basic metals as they were in the 1970s, whereas oils in general have moved increasingly from mineral to synthetics. Synthetic oils have greatly improved film strength, lubricity and higher temperature stability. At the same time sump capacities have virtually doubled, resulting in the oil doing fewer circuits of the engine and giving it more time to cool. Similarly you’ll notice that at the service interval modern oils are a lot cleaner than the black treacle they use to become, a result of the increased thermal stability.