new to diesel - what to look for in a test sail?

[Shearwater]

Changing from o/b powered sail to i/b diesel mobo and am testing a Volvo Penta 28 hp next week; what do I look for? Presumably blue smoke is acceptable and white smoke is not (Correct?) - it should start in ?how many turns or cranks? does clatter matter? should I listen for anything when changing into/out of gear, what degree of rattle or shake or vibration is acceptable? Pointers appreciated so thank you in advance ......

 

[30boat]

It seems you are expecting the worst.A well maintained and set up engine shouldn't smoke or rattle.If you get blue smoke that means not all the fuel is being burned.Black smoke means an overstressed condition,like a fouled or wrong propeller or a dirty bottom .Starting should be easy unless the weather is exceptionally cold.All diesels knock to some extent.Slow starting in normal weather may mean a number of things one of them being a clapped out engine but not necessarily.
The gearbox action should be easy but always stop at neutral between gears.
Hope this helps.

 

[TQA]

Make sure that the engine is stone cold when started. It is normal to use full throttle when starting a diesel. It should start within 2 to 5 seconds of continious cramking. If it requires a spray of diesel engine starter I would regard that as a bad but not total no go indicator.

Run it in gear at full throttle for at least 10 minuts and watch for everheating or excessive smoke. If either happens further investigation is required.

Ask for the service records and smell the engine oil. It should not smell burnt.

 

[MoodySabre]

The engine is presumably a VP 2003 - these do not have pre-heaters (glowplugs) so are a bit slow to start when it is this cold. If it has already been run when you get there then it should start straight away.

Watch it running on tick over as well as under load - this should show up poor engine mountings and alignment.

 

[matelot]

People write books to cover what you've just asked! /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif

Diesel engines in most basic ways are no different to petrol engines and the same criteria apply. For example, vibration is still mostly caused by alignment problems though a diesel is a bit rougher because of higher compression. And a worn diesel uses engine oil in just the same way a petrol one does. So use the same sort of criteria plus a few extras.

Diesels work by squashing the incoming air (which heats it up) and then squirting in the fuel. So the compression is a key factor and a wron engine with low compression will need a lot of cranking and maybe something like easy start to get it to run. Stick your hand on the blockl to see if the engine has been started before you arrive there - 0or better still arrive half an hour early. /forums/images/graemlins/laugh.gif

Having said that, in cold weather engines take longer to start anyway, and batteries yield less power as well. And some engines (you dont say which engine you are looking at) have little electric heaters to help starting and if these fail / work on only some cylinders, you can have difficulty starting up. They are cheap so dont worry in this case.

Dont worry too much about the smoke when the engine starts up and idles. The "choke" on a diesel usually injects extra fuel into the engine which in turn causes smoke. On my Volvo 2003, the engine used to smoke like an old destroyer until it was put under load at 2500 rpm and run - when it stopped almost completely. Yet it never used any engine oil and the injectors were in good condition. In any case, I've never found that you could tell much by peering at the smoke and trying to judge its colour except when I once ran a head gasket and the smoke then turned to large volumes of steam.

When going into gear check to make sure the clutch doesnt slip. Boat clutches are automatic in the sense you have no direct control of them so they do sometimes jerk a bit as they engage. Incidentally, the engine should idle from cold.

Judge also the outside condition of the engine. An owner who has a clean engine bay free of oil leaks and rust is much more likely to have looked after things internally as well compared to the owner of a rusty old lump.

Finally, you are more likely to frighten yourself about non problems than miss something important even with lots of knowledge. So take a pal along but chose someone who knows something rather than someone who talks a story.

 

[Anonymous]

If a diesel starts instantly in cold conditions with a battery that hasn't been on charge for a couple of weeks and doesn't make lots of smoke, you've probably got a good 'un. Standard trick for the vendor is to run up the engine before you arrive for the trial so it is a warm engine and fresh battery. Let the vendor know that you specifically want to see it start from cold (i.e. overnight) and let him know that you will walk away if you arrive and find it warm. Can't overstress the importance of that.

 

[chrishelen]

The VP 2003 is a good engine until things start to wear then its expensive, but most things have been covered in the posts above exept one, the gearbox splines, on engines with the numbers after 2300059195 the splines were modified, engines before that number had the weak splines ,the modification can be expensive.

 

[Skyva_2]

The DB Marine spline modification to the 2003 cost about £400 a few years ago, it may have risen since then.

Most engines will have had it fitted, but make sure.

 

[Shearwater]

Thanks folks for all your words and time given to write them. I'll take it all to heart and let you know the outcome. Thanks again, really appreciated.