Grey smoke

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shogi

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Hi ,Everyone!

My Beta 16 is 6 years old and has 700 Hrs on the clock. Recently after motoring for about 2 hrs, I noticed a grey smoke coming from the exhaust. Seams that the smoke is coming mostly when I’m at full revs, which is around 2000 RPM in my case.

The action taken so far without any results: propeller checked, air and oil filters changed, heat exchanger and water pump checked, exhaust elbow&pipes inspected. I took the injectors for servicing, but this didn’t help as well.

Next step, we’ll be checking the compression. Otherwise in neutral the engine is delivering 3600 RPM without any smoke at all.

Any ideas, please!
 
shogi said:
Hi ,Everyone!

My Beta 16 is 6 years old and has 700 Hrs on the clock. Recently after motoring for about 2 hrs, I noticed a grey smoke coming from the exhaust. Seams that the smoke is coming mostly when I’m at full revs, which is around 2000 RPM in my case.

The action taken so far without any results: propeller checked, air and oil filters changed, heat exchanger and water pump checked, exhaust elbow&pipes inspected. I took the injectors for servicing, but this didn’t help as well.

Next step, we’ll be checking the compression. Otherwise in neutral the engine is delivering 3600 RPM without any smoke at all.

Any ideas, please!
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Delivering full speed off load is no indication, it requires very little fuel or power to achieve that. Is there a power loss at full throttle on normal load? Possibly a leaky valve reducing compression - have you checked valve clearances? A leakdown test is better than a straight compression test fro tracking things like this.

Are you sure that it is grey smoke, and not steam? If the cooling system is working a little below par the exhaust will produce steam at high power as there is insufficient water to keep the exhaust fully cooled..
 
When did you last have the injectors and fuel pump servced? Grey smoke is indicative of a problem with fueling. Blue smoke is burning lub oil. Steam rises from the transom and disperses easily. Smoke tends to stay low over the water.

I had a wee problem earlier this year, myself and this was the advice I was given. In my case an Italian Tune up sorted the problem which was a sticking injector.
 
2000 is nowhere near full revs. You should be able to achieve at least 3400 - the maximum governed speed is 3600. If you are only getting 2000 under load your prop is either heavily fouled or is far too big for the engine/boat combination.
 
Tranona said:
2000 is nowhere near full revs. You should be able to achieve at least 3400 - the maximum governed speed is 3600. If you are only getting 2000 under load your prop is either heavily fouled or is far too big for the engine/boat combination.
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We once set off for the season without checking the prop and were puzzled by the engines inability to reach normal max revs and speed. When we got to where we were going, I checked the prop and found it was very heavily fouled. Once cleaned, everything was back to normal and cleaning the prop is part of the start season list. You may find that something like this lies at the heart of the problems.
 
Thank you to all for the replies!

The H/E was serviced recently after the problem appeared and I’m sure, that it is a smoke and not a steam, but I’ll place a mirror just in case. Definitely smoke is coming from the oil cap when opened.

The injector were serviced yesterday and maybe is a good idea to try the Italian tune for 15-20 min before taking further actions (compression test, leaky valve and valve clearance). Can I do this while the boat is tied to the pontoon or I have to be really motoring?

As some of you suggested 2000 RPM is a bit far from what should I do and next time the boat is out I’ll measure the prop. The thing is that I had her for 5 years with the same engine&Volvo 110 S and I never saw her smoking at high revs. I can see the propeller from the pontoon and doesn’t look bad for me.

Also, I was thinking whether can be a dirty fuel problem. I never use any additives for the diesel.
 
Have you ever seen full revs under load? If not then the chances are by restricting revs in the way you have been the bores are probably glazing, which could account for the smoke.

Seriously get the correct prop. Presumably the Beta replaced a Volvo which had less power but crucially lower revs, so a lower shaft speed. You can get an idea of prop size by putting your boat details into the Propcalc programme on www.castlemarine.co.uk
 
No, never! ' Bore glazing' sounds scary...is it?

I can't use the 'Pitch calculator' with my Windows 7 and will have to try from a different PC. Thank you for the site anyway!
 
shogi said:
No, never! ' Bore glazing' sounds scary...is it?

I can't use the 'Pitch calculator' with my Windows 7 and will have to try from a different PC. Thank you for the site anyway!
Click to expand...

The pitch calculator does work with Windows 7. Just ignore that the web site states Windows XP and Vista and download the file and install.
 
shogi said:
Thanks! Not sure how to determine the 'prop slip'.
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Don't bother with that - not important on a sailboat auxiliary. The important data a LWL, displacement, engine power and revs, gearbox reduction ratio and number of blades.

Yes, bore glazing is nasty. Overloading the engine and restricting revs as you are can cause the bores to "glaze" over - that is rather than having a slightly pitted surface to hold oil and keep a good seal on the rings, it is polished and oil leaks past - hence the smoke in the exhaust. Can also lead to reduced compression.

The worst thing for these small diesels is low speed running. They are designed to run at revs equivalent to 75% power, which on your engine is about 2500. The prop should be sized so that you get maximum speed at close to 3600 and your cruising speed at 2500 or thereabouts.
 
Thank you, Tranona! I'll go further into the prop sizing and it is really pitty that I don't know the size of my 2-blade prop. It could be 14X9, 14X8 or 14X7
Can the bore glazing do further demages?
 
Eventually (and long before the typical 8000 hours design life) performance will fall away and oil consumption increase. It may be possible to clean the bores up with what is known (unsurprisingly!) as a glaze buster tool, but this requires removal and stripping. Yacht auxiliaries only do low hours a year so it may be some time before it gets bad, but in terms of the expected life of an engine it would be premature.

If you have a Volvo prop the size is usually stamped on the boss, but of course you will have to get it out of the water to check. Once you have the correct size prop and can get the revs take it for a good run at near maximum revs.
 
SandgroperWA said:
Please tell me what an Italian tune is, cheers from down under
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Imagine yourself in an Alfa Romeo, Sophia Loren by your side, clear autostrada and a heavy right foot. You know you (and the Alfa) feel better after that!

Equivalent of blowing the cobwebs out, so 30 minutes at near maximum revs under load
 
An "Italian tune-up" is short run at max power and /or maximum revs intended to blow the cobwebs from the exhaust system. It has the added advantage of burning off any soft carbon in the combustion chamber.

At least that's the theory. So called because all italians drive like that all the time.
 
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