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Mechanical Surveys

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Hi All

As we are starting to look for our first coastal boat, I need some information about having mechanical surveys carried out.

When it comes to 1.5L BMC engines, I am fairly happy, but now looking at these big Volvo Penta lumps with outdrives, I get all nervous, as I don't know the first thing. When we find the right boat, I therefore intend to commission a mechanical survey to give some peace of mind.

First question - any recommendations of mechanical surveyors?

Second question - I have heard varying stories about the benefits of having an oil analysis carried out, ranging from "they are essential" from on broker, and indeed a couple of members on here; to "they are not worth the paper they are written on, don't waste your money" from another broker. What is the consensus here? What can they actually tell you from a drop of oil?

Help, as always, is most appreciated :grin:

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The only people to do a full drive train survey in my view are the factory trained dealers of what ever motor and drive you may select. The reasoning is that they will have seen far more of these lumps than a general mechanic however good that guy may be. They will have seen what faults recur and the oddities and nuances of the equipment and will have read all the factory bulletins and if local to the sale may even know the history of the boat.

Not really much good simply saying oil analysis is a good thing or not without an argument for or against, I would be interested to hear that broker’s argument against.

An oil analysis will tell you the general condition of the actual oil and filters, but that is almost academic as I’m sure you would change them on delivery or soon after as a matter of course. More importantly it will reveal the condition of the workings of the motor, bearings, rings, pistons etc by measuring various suspended metals. It will show the presence of small quantities of water, fuel, antifreeze constituents, acids and the like thereby picking up problems early on. There is in fact a good case for sending a little of the oil away for analysis every year or so when you change the oil and filters let alone just at survey time.

The same can be said of the hydraulic fluid in the gearbox if shaft drive and especially the lubricant in the stern drive.

It is interesting to note that oil analysis was not introduced by oil companies to sell more oil as a common misconception would have people believe. Fact is it was introduced by plant companies as a cost saving method in order to extend oil and filter change intervals by not doing so until contaminant levels reached a benchmark rather than simply hours run or time elapsed.

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I paid for an oil analysis when we bought our boat 10 years ago. It was somewhat inconclusive, due to such things as a recent oil change and very low usage in that season.

So, a waste of money? Maybe, but I felt better for having it done, as at least it didn't find any huge disaster. It's a small outlay in the great scheme of things and you never know......it may just highlight a problem and save you money in the long run.



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Something to the effect of "What do I care how much silicon is in the oil, it doesn't mean anything to me".


A very reasoned argument indeed, I can't fault it and it would certainly give me a heightened confidence in the professionalism of that particular broker. :roll::roll:

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A very reasoned argument indeed, I can't fault it and it would certainly give me a heightened confidence in the professionalism of that particular broker. :roll::roll:

Quite! Funny how it's the same broker I had a gripe with a couple of weeks ago ...... :naughty:

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I would be interested to hear that broker’s argument against.

Would think a good argument against an oil analysis is that it is likely to pick up the piston rings in the sump.

For £75 it has to be worth it even if it is non conclusive, it does at least stand a chance of showing up a duff lump.


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Well i had an oil content test before i bought Tottyme and cost around £80 for a 2.5 Bmc engine i was quite shocked at the amount of metals /antifreeze etc found in the sample,resulting in me still buying the boat at reduced cost but changing the engine.it told me the engine altho 27 years old and an ex hireboat was breaking down inside ie.cylinders/leaks/so much different metals found,yes,i thought it was worth it.

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