Smoking Volvo 2003T above 2500 rpm

[whiteoaks7]

I'm sorry about this post - I know this has been discussed before but I can't find the answers. My VP2003T has started producing copious quantities of thick black smoke and smell of burnt carbon, above 2300 rpm. Below this it seems ok (or small enough not to be noticed).

Due to a plastic bag over the inlet the engine (fresh water cooled) set off the overheat alarm and had to be run for five minutes on tickover to get to a safe place to clear the problem. Since then it had been run for two hours per day on a mooring to charge batteries at about 1500 rpm. Today we sailed Dart to Plymouth using the engine for about two hours and found this thick black smoke screen developed any time we exceeded 2300 - no difference whether engine was hot or not.

Engine is 1992, due for full service but oil changed recently.

I've tried to give facts here without leading you - the plastic bag incident may or may not have been a contributor. Can I please have your ideas and again apologies for not finding the earlier posts.

 

[Frontier]

I recenlty had lack of power at the top end and lots of smoke whne trying to plane, turned out it was blocked air filters,

COL a fellow forumite spotted it right away. Not saying its your problem, but worth a look.

 

[Landale]

Exactly - Air filter /forums/images/graemlins/cool.gif

 

[Saddletramp]

having my injectors checked the other day I was told that black smoke is diesel burned without air. This could be caused by timing or as seems more likely in your case air filters.

For info I was also told that white smoke would more likely be timing as well (injecting too late) rather than faulty injectors.

 

[rebelae]

If I'm not mistaken, at this stage of the season, it could just be a dirty bottom (the boat, that is!).

Theory is that the drag from the weed limits you to whatever speed it is you're doing at 2.3k revs. As you continue to open the throttle beyond that level, the boat doesn't accelerate any more, so the prop can't turn any faster (you're not likely to get cavitation), and the engine also doesn't turn any faster. However, you're still putting more fuel into the system, which isn't getting burnt, and it comes out the end in black smoke.

I did something similar (opened the throttle right up) up the western Solent a couple of years back in an "attempt to burn the turbo clean." Took me about an hour to realise that there wasn't likely to be that much rubbish in there, by which time I'd left a big black trail from Lymington to Beaulieu...

That being said, and seeing what you said about charging the batteries, I have been told that idling a 2003T isn't a great idea as it does coke the turbo up, as they don't kick in (and so get properly hot) until 1800 revs, and that lets the exhaust deposits settle on the blades (which get heavier, so harder to spin, so it takes more speed to get going, and so on in a vicious circle). Previous owner had to fork out 4 figures to get it cleaned (amazing how that sort of thing concentrates your mind).

Certainly check the air filter too - too much fuel for the air to burn (from excess throttle) or not enough air to burn the fuel (from blocked air filter) gives the same effect - but the motor boats have a different set of problems from us raggies.