Too much smoke on startup

[TheMadchef]

Hi all,
Been a while since my last post.
Question:
When I start my engine (inboard sterdrive Volvo 18hp diesel) there appears to be too much smoke emminating from the exhaust. It starts easily but a plume of dark smoke exhausts upon ignition. With the throttle at half to full at starting the RPMs lag for about 4 seconds then catch up to the throttle setting and I ease it back to 1800 RPM for warm up. The oil and filters have been changed fairly recently. What could be the problem? I hate to ask questions like these but am a newbie to diesels and won't be taking my diesel engine course until the winter.
The engine runs well overall but does seem to have a fairly high vibration until it really warms up.
Any advice is greately appreciated!

[F4d3d]

I spent some time on a boat with a Volvo Penta MD2, and there was a fair bit of smoke at the start-up as well. I talked with a mechanic about it and he said it was pretty normal behaviour. But I guess this is subjective since I can't see exactly how much smoke you have compared to what I had...

[Hartley18]

Sounds like a fuel issue to me.. but then I'm only discovering these things myself and, at the moment, fuel seems to me to be responsible for nigh everything the matter with diesels.

Which engine do you have exactly? At 18hp, I'm guessing it isn't a single-cylinder one.

[ffiill]

Dont know this engine personally but when there is a lag on start up might suspect a sticking injector which clears as it gets warm-my four cylinder Mercedes does this sometimes on one and occasionally two injectors.Injector(s) may need testing and cleaning?
Google this as there are various sites telling you about diesel smoke diagnosis-its colour-and smell!

[St Anna]

As FFiill says - I would look at the injectors - they might be starting to glass up. The colour and smell will speak volumes. Is it leaking any diesel through the exhaust when under load.

Have you run it under load? Or have you just let it tick over? Most naturally aspirated diesels need to be under load so - in gear and cruising revs at least when in a marina - (mooring lines will be fine)

I had a MD7A in a previous boat - ( Old volvos are nicknamed "the green death" - cant think why) It would send smoke signals.

Does it run normally otherwise -are the vibration only at certain revs/ in gear etc etc.

Go for a motor - really use the engine for a good days run!! Clean it out.

Let us know

[Ilenart]

Throttle at half to full for startup and then running 1800RPM for warmup sounds like a lot of revs. I would'nt normally exceed 1,000RPM's for starting and warmup would normally be 600-800RPM. If you used less revs it might solve your excess smoke issue, plus result in a lot less wear on the engine.

Ilenart

[ffiill]

To start any diesel other than modern computer controled ones procedure is preheat if you have heaters;full throttle giving max.fuel and air;start and immediately throttle back to about 1000 rpm for warm up.

[BobS2]

My little yanmar 1GM10 was smokey & sooty on start up until I started leaving the fuel shut off cable in the shut-off position. Seems better now.

[mylynne]

This could almost be registered as an OMG. Everything everyone has said could be legitimate issues with your motor. Diesels are very finicky creatures. They must have clean fuel and clean oil. These two points can not be underscored enough. I change my oil every 75 hours and change the oil filters every 25. They are really cheap. Fuel filters I check the racor each start up and change the fuel filters every 75 hours. Overkill? Absolutely. But it's cheap overkill and not difficult to perform. You may indeed have an injector going bad. They are very simple to have flow checked at a shop. Your mixing elbow could also be clogged with soot as could the manifold. It could also need the valves re-set.

Best tip I can give on any start up is this. Upon start up, keep your RPMs to a minimal. High revs on a cold motor are only hurting the engine. If you are going to sit at the dock put the boat in gear. These little engines must be under a load. Some of the biggest mistakes made by sailboaters are not allowing the engine to reach full operating temeratures before shut down, not running the engine under a load, especially when charging batteries and dirty fuel, filters etc.

Finally, even if it smokes at start up, does it run fine with the smoke going away in a few minutes? If so, I'd have a flow test done on the injectors and check the mixing elbow and manifold for soot build up. If those damn pipes become clogged with rust and soot they have a pronounced effect on the motors operation.

[MedSailor]

Originally Posted by mylynne

This could almost be registered as an OMG. Everything everyone has said could be legitimate issues with your motor. Diesels are very finicky creatures. They must have clean fuel and clean oil. These two points can not be underscored enough. I change my oil every 75 hours and change the oil filters every 25. They are really cheap. Fuel filters I check the racor each start up and change the fuel filters every 75 hours. Overkill? Absolutely. But it's cheap overkill and not difficult to perform. You may indeed have an injector going bad. They are very simple to have flow checked at a shop. Your mixing elbow could also be clogged with soot as could the manifold. It could also need the valves re-set.

Best tip I can give on any start up is this. Upon start up, keep your RPMs to a minimal. High revs on a cold motor are only hurting the engine. If you are going to sit at the dock put the boat in gear. These little engines must be under a load. Some of the biggest mistakes made by sailboaters are not allowing the engine to reach full operating temeratures before shut down, not running the engine under a load, especially when charging batteries and dirty fuel, filters etc.

Finally, even if it smokes at start up, does it run fine with the smoke going away in a few minutes? If so, I'd have a flow test done on the injectors and check the mixing elbow and manifold for soot build up. If those damn pipes become clogged with rust and soot they have a pronounced effect on the motors operation.

You change the oil every 75 and the filters every 25? How do you change the oil filters without spilling (changing) the oil?

MedSailor