I want to stop smoking

[Beadle]

But more immediate I want to stop Olive smoking

Olive is a 34ft Colvic Watson with a Perkins 6/534 engine - 6 cylinders 120 HP.

She has always since I've owned been on the smoky side but seems to be gradually getting worse.

I had the injectors taken out and serviced by a diesel specialist. One injector was replaced.

It made little or no difference.

The engine doesn't burn an excessive amount of oil and doesn't appear to lose water although it does run a bit hot if running high power for a long period.

When I say smoiking I means a sizable cloud of light coloured smoke drifting across the marina when I fire up. Reduces a bit when warned up but even at tickover here is more than any other boat.

Any ideas would be much appreciated.

 

[sarabande]

I had a Thorneycroft on my CW 34. It did the same on startup, but the smoke cleared when the engine warmed up - which took about 30 minutes each time. I guess the silencer system needed a lot of heat to evaporate the oil condensed inside it when used for a short run (which was usual).


Engine temp reached 70 - 75C, so it was a possibility of overcooling for me.

What temps are you running at when under load for a while ?

Are you using a quality diesel, or standard tractor red ? Perhaps try a cupful of 2 stroke oil into the tank; I cannot be positive because of lack of scientific observation, but subjectively the 2 str oil made mine much easier to start and less smoky to run.

 

[pampas]

reseat the valves or at least set the tappets, this usually reduces smoke.

 

[Bosun Higgs]

You can expect smoke when first fired up as the engine burns off excessive fuel needed to start from cold. You dont see that on modern car diesels thanks to catalysts / filters etc but you will on an old fashioned marine diesel with mechanical injection.

Once the engine is warm you need to decide whether its emitting lube oil smoke or diesel. They say that diesel smoke is black and lube oil is blue but I never find it easier to tell. Is you engine using lube oil?

If it is using lube oil then there are two likely problems - bore wear or valve oil seal wear. There are ways of telling which one but since the cure for either involves removing the cylinder head then thats the way I always go. Once done you can check bore wear easily.

If your engine is not burning lube oil but the smoke comes from diesel, then in theory its simple to deal with. Your engine injects fuel as instructed by the throttle lever, and it then accelerates until it is sucking in as much air as will burn that diesel correctly. So if you have something that is stopping the engine accelerating as much as it needs ( fouled hull, rubbish round the shaft, wrong prop etc) it will have more fuel than air and will smoke.

It will also smoke if one of the injectors is dribbling neat fuel into the combustion chamber. And if the air filter is badly clogged.

I've tried to put this all in a logical sequence. What you need to do is to tackle it bit by bit starting with the simple things. Make sure the hull is clean, the shaft turning freely, the asir filter clean, the injectors not dribbling. Then check oil useage etc

 

[Beadle]

Thanks everyone

I think I'll start with the tappets and take it from there.

Cheers

 

[Tintin]

You can expect smoke when first fired up as the engine burns off excessive fuel needed to start from cold. You dont see that on modern car diesels thanks to catalysts / filters etc but you will on an old fashioned marine diesel with mechanical injection.

Once the engine is warm you need to decide whether its emitting lube oil smoke or diesel. They say that diesel smoke is black and lube oil is blue but I never find it easier to tell. Is you engine using lube oil?

If it is using lube oil then there are two likely problems - bore wear or valve oil seal wear. There are ways of telling which one but since the cure for either involves removing the cylinder head then thats the way I always go. Once done you can check bore wear easily.

If your engine is not burning lube oil but the smoke comes from diesel, then in theory its simple to deal with. Your engine injects fuel as instructed by the throttle lever, and it then accelerates until it is sucking in as much air as will burn that diesel correctly. So if you have something that is stopping the engine accelerating as much as it needs ( fouled hull, rubbish round the shaft, wrong prop etc) it will have more fuel than air and will smoke.

It will also smoke if one of the injectors is dribbling neat fuel into the combustion chamber. And if the air filter is badly clogged.

I've tried to put this all in a logical sequence. What you need to do is to tackle it bit by bit starting with the simple things. Make sure the hull is clean, the shaft turning freely, the asir filter clean, the injectors not dribbling. Then check oil useage etc

Very clear and helpful. Thanks.

 

[rib]

im no engineer,but i know personally of a case where the fuel pump was /retimed/turned/adjusted in some way and this cured the smoking problem period.but not on a boat not that should mean anything

 

[PCUK]

Have you checked the injection timing?

 

[Beadle]

Err

No

I'll see about getting it checked when I next see my ex marine engineer mate.

It sounds a bit technical for me

Thanks

 

[Bosun Higgs]

Beadle - start with the basics. Dont fall into the trap of trying the exotic / unlikely causes first.

 

[dunmor]

Beadle - start with the basics. Dont fall into the trap of trying the exotic / unlikely causes first.

i will second that, air filter first, will make a big difference if engine is gasping for air. i can also agree with putting 2 stroke into the fuel tank, improves starting and seems to run smoother, i dont know why but it does.

 

[rib]

this 2 stroke business,does it lub the cylinders ?.strange one.one would have thought that the oil burn off would make more smoke ?.i dont for one min disbelive it/you.some things just work because thay do.