Smoking BMC diesel

[SimonA]

My BMC 1.5 diesel engine seems to be smoking more than normal. I know they smoke at start up, but this is once the engine is hot.

The smoke looks to be white/grey. It's not a huge amount, but enough to be noticeable when up against a dock or in a lock. It's also leaving a black sooty mess on the hull near the exhaust.

The engine has done about 1500 hours and I'm not sure when or if the injectors have been serviced. It has had an oil change recently.

Any ideas of what to look at first?

 

[alb40]

My old boat had a bmc 1500.

I had some white grey 'smoke' before, put it turned out to be a collapsed pipe which impeded the water flow enough to make it run slightly hotter than usual, so it was just steam.

Black mess around the exhuast is normal, everyone i know with these engines got it.

Check normal culprits for overheating, and fouling of hull / propeller etc etc

hope that helps, Alex

 

[Opsguy1979]

I had a Freeman a few years back and exactly the same as Alex it just turned out to be steam. Changed some old looking water pipes and new impellor and bobs you uncle all ok.

Karl

 

[robertevans]

i WAS A CITY AND GUILDS TIME SERVED HGV MACHANIC
black smoke unburnt fule
blue smoke oil
white smoke exes fule(cold starting) or water getting into engine or exhoust sytems as outher posts say steem.
hope this helps

 

[andy_wilson]

Black smoke is excess carbon particles due to unburned fuel due to poor breathing or overloading engine. Typical culprits are blocked air filter or air intakes or new engine room insulation, or collapsed / delaminated exhaust pipe. Also, fouling on hull or prop. In extreme, gearbox or shaft bearing problem.

Blue smoke is usually oil so you're OK on that.

White / grey smoke can be steam OR, if it smells rank, it could be unburned diesel due to a poor injector dribbling it in rather than spraying.

As you are inland, I wonder if the engine is ever given it's head. The cylinders will carbon up if they don't get a good blast now and again, and this can coke up the injectors too. It can be a bit antisocial, but worth lashing alongside securely and running her hard astern for 10 - 15 minutes to blow it out. Then see how it is afterwards.

If you are handy, and the design allows it, pull the injectors and re connect the wrong way round and turn her over on the starter. A good injector will fire pulses of fine mist. They need a service if they dribble or squirt a jet (which you should beware of, so keep your distance whilst observing).

 

[SimonA]

[ QUOTE ]
OR, if it smells rank, it could be unburned diesel due to a poor injector dribbling it in rather than spraying.


[/ QUOTE ]

You might have hit on something there. It does smell. But as I have never owned a diesel engined boat before I thought that was normal. My exhaust exits mid way along the port side of the hull next to the centre cockpit and the smoke sometimes blows into the cockpit. It does smell a bit like fish & chips.

I don't know anything at all about diesel engines, so it sounds like a job for a mechanic. At least it 's not as bad as a boat I passed last week on the river, it was churning out black smoke to such an extent that you could not see for a couple of minutes after they passed.

 

[andy_wilson]

Main difference apart from smell is that steam disperses rapidly, smoke hangs around.

 

[oldharry]

[ QUOTE ]
white smoke exes fule(cold starting) or water getting into engine or exhoust sytems

[/ QUOTE ]

Errm, I dont think HGVs have sea water cooled exhausts Robert! The vast majority of boats have the seawater coolant running into the exhaust just after the manifold. This does 3 things: 1: it keeps the exhaust system cool, otherwise it can set fire to the boat. 2. It helps to silence the exhaust - boats rarely have silencers like on HGVs. And 3: It fools owners into thinking their engines are producing white smoke if the water flow is insufficient and turns to steam with the exhaust heat! 95% of 'white smoke' complaints on boat engines are actually steam from over-heated exhausts. /forums/images/graemlins/confused.gif

 

[robertevans]

old harry thanks for the info.
thay say you sould not go to bed without leaning somthing, thanks to you i can sleep tonight for the first time in 2 years 3 months and 1 day.
thank again
rob

 

[oldharry]

Sleep tight! Folks do say I often have this effect on them.... /forums/images/graemlins/blush.gif