Smoke from volvo diesel

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njamesphoto

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on my volvo 2030 diesel, anything more than 2300 rpm under load the cooling water from the exhaust turns dark grey, is this normal. I suppose it would be like black smoke if there was no water. 300 hours and regulary serviced. flat out revs are nearer 3000rpm (never ran near this) so i find myself limiting it to 2000 rpm max or could i give it more?
 
If the boats been left afloat for the winter, it might just be fouling on the hull and/or prop......... in which case time for a dry out and scrub off.

If the boats only recently been launched, then it's something else. /forums/images/graemlins/wink.gif
 
It sounds like incomplete combustion at higher revs. Possible causes are manifold. Discounting a choked air filter, it may be a partialy blocked exhaust, tight valve clearances or even a mismatched propellor.....Other possibilities are low compression, worn high pressure fuel pump or poor injector spray pattern.
These tend to cause Black smoke, while white smoke is mostly the result of unburnt fuel in the exhaust, maybe a broken head gasket or piston rings and VERY tight valve clearances.

Blue smoke is associated with burning Lub-oil, unlikely in a 300hrold engine, although once again a broken oil scraper ring might cause this. A too full sump too, perhaps.
 
i read with interest the mismatched prop, its a 4 year old boat that has a bruntons 3 bladed folding prop fitted by the previous owner we can only get 6 knots under power (37 foot jeanneau) and more under sail. Similar boats seem to be happy at 7 or 8 knots. If the pitch was to fine would this be a symptom?
 
Diesel engine power is determined by the amount of fuel injected. Assuming your throttle is set propperly, a mismatched prop will prevent the engine reaching its optimum speed for the amount of fuel provided. This may cause incomplete combustion.

A too coarse pitch will overload the engine, a too fine one over rev it.

If, for example you ARE running a too fine pitch prop, you won't get the speed from your boat at full engine revs. If your prop pitch is too coarse, the engine will never reach full rpm.

I don't know much about folding props, does it open fully?
 
It would. The only way to do this really is replace the blades, quite an expensive option, methinks. If it were my boat, I'd consult my friendly neighbourhood marine engineer before embarking on such a strategy. in case it's something else.

Do you know what the pitch of your current prop is? Brunsons ought to know the best pitch for the engine/boat combination and they should have a record of the prop provided to your vessel's previous owner, it's not that long ago after all.
 
I also have th 2003. My owners manual is down on the boat but I seem to remember that the max revs is 3400. If I am right , then a prop or dirty hull limiting the engine to 3000 is likely to cause excess unburnt fuel going into the exhaust - the throttle controls the fuel supply so a full throttle would be delivering fuel for 3400 rpm whilst the engione would be sucking in air at 300rpm. Hence rich mixture etc.

There are lots of other possible causes, but start with the simple inexpensive ones first. Air supply - is the engine so well sealed that it cant breath. Clogged air filter. Injectors not spraying properly.

Any diesel engine will produce some black smoke when the throttle is suddenly opened and wont go back to clear until revs rise to match throttle.
 
Take off the oil filler cap while the engine is producing this black/grey exhaust. If a lot of smoke comes out it is most likely coming up from the sump - bad news. If not a lot coming out then get your injectors serviced.
 
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