Smokey engine when not loaded

[Richard Martin]

I have a Barrus Shire 1200 engine which is rather smokey at low revs (1000-1100).

 

I have had the engine checked when it was serviced and the engine is fine, the thermostat is the correct temperature one (some were fitted with too low a temperature).

 

The engineer suggested that the most likely problem was that the engine was not being loaded.

 

We find that when we increase the revs to around 1300 the smoking disappears and you just get the odd puff of smoke but most of the time it's clear exhaust.

 

My problem is that at 1300 revs we are often causing a wash and we do not want to do this being responsible boat owners.

 

Not being technical I was wondering if we reduced the prop size it would mean that our normal crusing speed would then be achieved at around 1300 revs.

 

Does this make sense or should I just put up with it.

 

All sensible suggestions welcome

 

Richard Martin

[Guest]

I have a Barrus Shire 1200 engine which is rather smokey at low revs (1000-1100).

 

I have had the engine checked when it was serviced and the engine is fine, the thermostat is the correct temperature one (some were fitted with too low a temperature).

 

The engineer suggested that the most likely problem was that the engine was not being loaded.

 

We find that when we increase the revs to around 1300 the smoking disappears and you just get the odd puff of smoke but most of the time it's clear exhaust.

 

My problem is that at 1300 revs we are often causing a wash and we do not want to do this being responsible boat owners.

 

Not being technical I was wondering if we reduced the prop size it would mean that our normal crusing speed would then be achieved at around 1300 revs.

 

Does this make sense or should I just put up with it.

 

All sensible suggestions welcome

 

Richard Martin

Is it black smoke? If so that would suggest an overloaded engine. I would have expected this at all revs though if it was over-propped.

[nigel carton]

How old is the engine? When serviced was the timing checked? has the fuel system been looked at, ie fuel filters, injectors, diesel treatment? I think changing the prop is the last resort.

Like Cateweasel said, is it black or white smoke?

 

Nigel

[Cafnod]

Colour of smoke please?

How long have you had the smoke?

Is it the original engine in the boat?

what length weght is the boat?

What sort of service was carried out?

 

Have the following being changed:

Fuel, Oil and Air filters.

 

Have the following been checked:

Fuel water trap

Injection pump timing

Quality and type of fuel, for example if the engine has been run on gas oil extensively with no engine oil added to help lubricate the fuel injection equipment it could have worn excessively.

Fuel injectors

Fuel injector pump metering valve.

I would rule out ALL of the above before going any further, certainly before changing prop size.

[Speedwell]

The common cure for light load smoking is to advance the injection point, if it's possible with that engine. As you can probably do this for free, it's worth a try before you try the expensive stuff.

Arthur

[Richard Martin]

How old is the engine? When serviced was the timing checked? has the fuel system been looked at, ie fuel filters, injectors, diesel treatment? I think changing the prop is the last resort.

Like Cateweasel said, is it black or white smoke?

 

Nigel

 

 

The engine was new with the boat in 2002, we bought it in 2004.

 

The smoke colour is whitish blue, not black.

 

The fuel and oil filters were changed last month with the service.

 

Fuel has always been bought from Chandleries on the canal system.

 

We have added Fuelset which seems to make it better..ish but does not cure it so could be coincedence.

 

Richard

 

The common cure for light load smoking is to advance the injection point, if it's possible with that engine. As you can probably do this for free, it's worth a try before you try the expensive stuff.

Arthur

 

 

How is this done, can it be done by a novice or should I leave it to the experts.

 

Richard

[Speedwell]

How is this done, can it be done by a novice or should I leave it to the experts.

I don't know enough about your engine to know if it is even possible.

On BMCs the injector pump is mounted by bolts through 3 slotted holes. All you have to do is slacken the bolts and turn the whole pump in the opposite direction to its direction of rotation. The bolts can be difficult to get at and the pump is springy to move due to all the pipes connected to it but there is nothing technical about it. Mark where you start from and try a little at a time.

There must be somebody on this site who knows the engine well enough to let you know if your engine has this adjustment.

arthur

[matt]

I get white/blue at low revs when the air filter is clogged.

 

To fix it I clean the filter (mine gets oil on it every 40 miles or so - it's not overfilled according to the dipstick),

then let the engine warm up properly and give it a good blast out in neutral, couple of puffs of black smoke and it's fine for another 40 miles.

 

Matt.

[dor]

I get white/blue at low revs when the air filter is clogged.

 

Now here's a funny thing: I went to change my air filter the other day. My engine has one of those upturned tin cans containing a paper element type filter. I fished out the new one, but although it was supposed to be a match for the old one, it was a bit larger in diameter. As I was fitting it, it occured to me that it would actually seal quite well inside the upturned pan, and so prevent air getting sucked in. I decided to leave it off completely, and thought that it might be a bit noisy but I'll live with it for a bit.

 

Strangely the engine seems quieter. I therefore surmise that without the air filter element in, it is breathing easier and therefore isn't working so hard.

 

Now the decision is, do I need an air filter at all?

 

The tin can over the intake will stop anything getting dropped down the hole. Unlike a car, it isn't going to go through a dusty environment or get stuff kicked up from the road. Being under the floor of a cruiser stern, the engine is sucking in air that might be a bit warm and even slightly oily, but I don't think that is going to hurt it.

 

The engine definately sounds happier, and despite its 8,000 hours, only produces a bit of black smoke under full load (so normal).

 

Are papaer element air filters really that necessary or would a bit of oily scrunched-up chicken wire (like my old '60s Bantam bike) be adequate?

Edited June 9, 2006 by dor

[Richard Martin]

I get white/blue at low revs when the air filter is clogged.

 

To fix it I clean the filter (mine gets oil on it every 40 miles or so - it's not overfilled according to the dipstick),

then let the engine warm up properly and give it a good blast out in neutral, couple of puffs of black smoke and it's fine for another 40 miles.

 

Matt.

 

 

Thanks, I will try replacing the air filter

[Sir Nibble]

would a bit of oily scrunched-up chicken wire (like my old '60s Bantam bike) be adequate?

I really really wouldn't. Oil based air filters can be dodgy, get it wrong and your engine will run away! like, 30 knots followed by the sound of con-rod exiting through crankcase!

[dor]

Ah yes, good point Snibble.

 

Perhaps just the wire then?

[Denis R]

If you've got a clean air environment you might get away with it, but if there's a chance of sucking in airborne particles you've effectively got a fine grinding paste. It'll take a time to work, but eventually the ring fit will deteriorate, especially when it's trying to seal on a 22:1 compression ratio.

I'd keep the paper filter.

[Guest]

Our last engine was a one cylinder Yanmar whcih had no air filter. I do not believe our new Vetus 415 has an air filter as such.

[Keeping Up]

I never cease to be amazed at the number of dog-hairs that I clean off our (foam in oil-bath) air filter every time I change the oil, particularly as our cruiser-stern rear deck board seals quite well to the steelwork by sitting on rubber draught-excluder strips all round. Since last summer I now remember to brush them away from the alternator coolong slots too. I can't imagine that much hair would be good for the engine. Every time I do this or brush the carpets I wonder how I haven't got a bald labrador.

[Baron & Mrs Boater]

How much "smoke" would you say is normal ?

 

My recently completely rebuilt BMC gives the occasional puff of bluish smoke or haze, especially if increasing revs, and I am paranoid about it ! (the last work cost me thousands!).

 

I have been told not to run it in neutral for about 6 months, to prevent bore glazing (I have been through all the old threads) so am I just being over sensitive ? After all some of the boats you see pump out lots of smoke and surely I should expect some exhaust emissions, but I am not at all used to diesel engines.

[Keeping Up]

How much "smoke" would you say is normal ?

It does depend on the engine. There's an old saying about Lister engines for example, that blue smoke was just the normal indication that you hadn't run out of oil yet, and if it stopped smoking you should switch off immediately and top it up!

 

Since my Perkins MC42 was new, it has always smoked badly (blue oil smoke) if you suddenly increase the revs as, for example, when you do an emergency stop. This is probably a result of being glazed due to alleged maltreatment by running in Neutral at low revs before the boat was even launched - Perkins assured me it was still within spec (just) by burning 3 or 4 litres between oil changes which are at 200 hours, and that it would get better as time went by. Well, 15 years and 6000 running hours later it is definitely a little better than it was; I hope I can finish this running-in period soon!

 

Allan

[Tommo]

I once had a Nannie 4 cylinder and that has no air filter either, just a silencer on the air intake.

 

Tommo

[DHutch]

Id still stick with a filter. Sometimes you can get away without. Our petrol outboard for instance just has a crude baffle. Same with some RC helicopters.

- But like allen says, he gets dog hairs on his, and its certtainly got to be better not to get them in the engine!

 

 

Daniel

[ayit]

Whats fuel set?

[Baron & Mrs Boater]

Did a google.....

 

http://www.mailspeedmarine.com/ProductDeta...ategoryID/39/v/

[DHutch]

Did a google.....

Good man!

 

 

- As per my sig!

[David Schweizer]

How much "smoke" would you say is normal ?

 

My recently completely rebuilt BMC gives the occasional puff of bluish smoke or haze, especially if increasing revs, and I am paranoid about it ! (the last work cost me thousands!).

 

I have been told not to run it in neutral for about 6 months, to prevent bore glazing (I have been through all the old threads) so am I just being over sensitive ? After all some of the boats you see pump out lots of smoke and surely I should expect some exhaust emissions, but I am not at all used to diesel engines.

I have just had the BMC 1.5 on my boat re-built, it has done 60 hours so far. We get a bit of light bluish grey smoke when opening up after a period of ticking over in neutral (moving out of a lock is the usual circumstance) and I can sometimes detect a light haze behind the boat when we are moving slowly, this disapears however if we are able to open the engine up for a good while. I have been told that slow running and idling in neutral is the worst thing we can do whilst the engine is running in, and the best thing I could do would be to take it for a good fast blast down the Thames. I have been assured that the smoking will diminish as the rings start to polish off the miniscule machining imperfections in the bores which are currently allowing minute amounts of oil to pass through to the combustion chambers. Whether this is true or not will be revealed in good time.

 

Like you, I was a bit concerned about the engine smoking, having shelled out a little over £3000 for an engine and gearbox re-build, but I did have the benifit of seeing the old engine in bits and it was in a very sorry state. I was also leaving huge clouds of blue smoke behind me all the time, and fuel consumption had increased by almost 50% so I had little choice. I am getting less paranoid as time passes on.

[Baron & Mrs Boater]

Thanks David, I am reassured. I was told to run the engine hard if I could, it is difficult without being near a river - so I had to find a broken down boat to tow !

[Richard Martin]

Just an update on my engine.

 

We have found the source of the smioke - the fan belt !!

 

It had a 50mm slot missing on the inner face, only the perimeter was remaining.

 

It seems that this was causing the alternator and water pump to slip so the engine was not being loaded.

 

Once we fitted a new fan belt the smoke was gone except at tick over when there was a small amount of smoke, but I can live with that.

 

If I did not see it with my own eyes I would not have belivieved it.