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Mad Harold

Excessive Smoke at high power

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BMC 1500 starts and runs fine,a bit of smoke from a cold start but none at normal canal speeds.

However, there is a bit of smoke when giving a good burst of reverse,or when on the river cruising at (a guess) 6 or 7mph,there is a slight blue haze.Not worried by this,but am concerned that when I give the engine full throttle it really smokes,enough to obliterate the canal behind.It needs to be seen to be believed.

The engine oil capacity is given as 4.7 ltr but my dipstick with the loop outwards goes to the bottom of the sump,and with the loop towards the engine it stops before the bottom.

At the last oil change I put in a 5ltr can of oil,and the dipstick at the bottom of the sump registered full,but with the loop turned towards the engine the oil was on the minimum mark.I topped up the oil to the max with the dipstick loop turned inwards. I thought nothing of this because I read on here that different size sumps were fitted to BMC engines but now with the smoke at high revs,I am wondering if I have overfilled the sump.

There is probably five and a bit ltr in, would overfilling cause excess smoke at high revs,? or is my engine just getting old and tired?

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1 minute ago, Mad Harold said:

BMC 1500 starts and runs fine,a bit of smoke from a cold start but none at normal canal speeds.

However, there is a bit of smoke when giving a good burst of reverse,or when on the river cruising at (a guess) 6 or 7mph,there is a slight blue haze.Not worried by this,but am concerned that when I give the engine full throttle it really smokes,enough to obliterate the canal behind.It needs to be seen to be believed.

The engine oil capacity is given as 4.7 ltr but my dipstick with the loop outwards goes to the bottom of the sump,and with the loop towards the engine it stops before the bottom.

At the last oil change I put in a 5ltr can of oil,and the dipstick at the bottom of the sump registered full,but with the loop turned towards the engine the oil was on the minimum mark.I topped up the oil to the max with the dipstick loop turned inwards. I thought nothing of this because I read on here that different size sumps were fitted to BMC engines but now with the smoke at high revs,I am wondering if I have overfilled the sump.

There is probably five and a bit ltr in, would overfilling cause excess smoke at high revs,? or is my engine just getting old and tired?

Does it keep smoking like this after several hours cruising?
Reason I ask is that owing to circumstances we lived in a marina for two years where the engine was used quite a bit for water heating/charging (I don't normally do this.) We set off at weekend and our Vetus was also laying a smoke screen; something it has never done before. It also felt like it was lacking in power, and like myself, not firing on all four. Two days and several running hours later normal service is resumed.
Just a thought.

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3 minutes ago, catweasel said:

Does it keep smoking like this after several hours cruising?
Reason I ask is that owing to circumstances we lived in a marina for two years where the engine was used quite a bit for water heating/charging (I don't normally do this.) We set off at weekend and our Vetus was also laying a smoke screen; something it has never done before. It also felt like it was lacking in power, and like myself, not firing on all four. Two days and several running hours later normal service is resumed.
Just a thought.

That would be due to accumulated oily condensed oilyness burning that's settled in the exhaust system because it wasn't  under enough load in the marina.  Mad Harolds engine sounds fine to me, maybe a little bit of the newness wearing off that's all. Using dipsticks on boats is always a bit hit and miss, angle of engine on its mounts, sideways list because of where your standing when dipping it ect.

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3 minutes ago, bizzard said:

That would be due to accumulated oily condensed oilyness burning that's settled in the exhaust system because it wasn't  under enough load in the marina.  Mad Harolds engine sounds fine to me, maybe a little bit of the newness wearing off that's all. Using dipsticks on boats is always a bit hit and miss, angle of engine on its mounts, sideways list because of where your standing when dipping it ect.

Reminds me of our ancient Yanmar which would often run away if the dipstick was not kept well below maximum.
That would seem a reasonable explanation for our Vetus as it is fine now.

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Thanks for the replies  folks,am going to drain the oil level to midway between min and max with the dipstick at the bottom of the sump and see if that cures it.

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7 minutes ago, Mad Harold said:

Thanks for the replies  folks,am going to drain the oil level to midway between min and max with the dipstick at the bottom of the sump and see if that cures it.

The dipstick shouldn't hit the bottom of the sump. If its an ordinary tin sump the 4.7 litres should be ok. A solid cast ally marine sump holds more I think.

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Over filling by a litre will not cause the engine to burn oil, blue smoke, unless it is well worn anyway.

I just chuck in 5ltrs of 20 50 and its fine.

Is the smoke blue, black or white?

If black either the engine is overloaded due to a prop full of washing or the prop is too big or its time to get the pump recalibrated and the injectors serviced. Could be too far advanced on the pump.

If white, you will be well down on power, with either misfiring due to low compression or retarded pump timing.

 

Its an old design indirect injection engine, not as clean as new ones and folk used to expect diesels to smoke back then.

Edited by hider
spelling

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36 minutes ago, catweasel said:

Reminds me of our ancient Yanmar which would often run away if the dipstick was not kept well below maximum.
That would seem a reasonable explanation for our Vetus as it is fine now.

When you say run away,do you mean the engine was running on it's own engine oil?

That was my worry,I have heard horrendous tales of "diesel runaway"

On initially giving my engine full throttle,the smoke has a dirty burning rubber type smell,which I think is the engine burning off the crap in the cylinders and exhaust manifold as the engine is generally working at a low power setting.But after a few seconds of full power the smell is definately oil burning.

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I wonder if its oil running down the valve guides and only getting sucked into the cylinder at  high revs? Especially if an oil change or top up  has just be done.

 

I have never known a BMC 1.5 run away. A Perkins with a similar pump, yes and a Lister when the customer ignored the rising oil level. maybe because we kept a close eye on the BMC oil levels.

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1 hour ago, Mad Harold said:

When you say run away,do you mean the engine was running on it's own engine oil?

That was my worry,I have heard horrendous tales of "diesel runaway"

On initially giving my engine full throttle,the smoke has a dirty burning rubber type smell,which I think is the engine burning off the crap in the cylinders and exhaust manifold as the engine is generally working at a low power setting.But after a few seconds of full power the smell is definately oil burning.

Yes it isn't the first time I had to stuff a T shirt down the air intake until I found the problem. Afterwrads I bought and kept a CO2 fire extinguisher to stop it, but of course it never did it again! I don't know much about BMC's other than reading stuff mainly on here,  but if Tony says that it is not a common problem,  I would be reassured by that. 

Edited by Guest

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Change the dipstick for the correct one as soon as possible. If it rests on the sump, vibration will cause it to wear through the sump pan creating a new drain hole. For reasons best known to BMC, dipsticks are made of harder metal than sump pans!

How do I know this?

Guess!

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4 minutes ago, sultan derocco said:

Change the dipstick for the correct one as soon as possible. If it rests on the sump, vibration will cause it to wear through the sump pan creating a new drain hole. For reasons best known to BMC, dipsticks are made of harder metal than sump pans!

How do I know this?

Guess!

Thanks for the advice.If I turn the dipstick loop towards the engine, it doesn't reach the bottom of the sump,and it fits quite firmly that way around.

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Bet the boat is overpropped, it wouldn't be unusual for BMC 1.5 installations

If so, the engine cannot produce enough power to turn the prop at the engines maximum speed. The governor tries to and pours fuel into the cylinders which the engine fails to burn properly. The result is lots of black smoke

Builders used to do this go get a lower engine speed at canal cruising speeds, which is nicer to live with

 

Richard

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9 minutes ago, RLWP said:

Bet the boat is overpropped, it wouldn't be unusual for BMC 1.5 installations

If so, the engine cannot produce enough power to turn the prop at the engines maximum speed. The governor tries to and pours fuel into the cylinders which the engine fails to burn properly. The result is lots of black smoke

Builders used to do this go get a lower engine speed at canal cruising speeds, which is nicer to live with

 

Richard

Thanks for you thoughts on this,but the smoke is blue, a hugh amount, you can't see the canal or towpath behind,it would be a credit to a warship dodging the enemy,and it stinks of,well,oil smoke.

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Check where the crankcase breather/s discharge. If either the tappet chest one or the rockerbox one is discharging into air inlet this is where the oil could be coming from.

Else its rings and bores. But I would think the compression would be down.

How well does it start fro cold? 

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I have known a BMC to run away, it had about 8 litres of oil in the sump plus whatever it had burnt and expelled from the engine! unusually, there was no diesel in the oil in this engine.

I have seen a few air cooled listers of various types with lots of diesel in the oil.

 

Tom

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32 minutes ago, hider said:

Check where the crankcase breather/s discharge. If either the tappet chest one or the rockerbox one is discharging into air inlet this is where the oil could be coming from.

Else its rings and bores. But I would think the compression would be down.

How well does it start fro cold? 

Crankcase breather pipe goes to the air filter from the tappet chest.No breather on the rocker box.Starts from cold wthin 4 or 5 revolutions with a small puff of blue smoke which clears quickly.

Tried checking compression with a spanner,but it was stiff to turn and after skinning my knuckles twice , I lost interest in doing this.I think I felt a couple of compressions,but because of the lack of leverage with a spanner and the stiffness of the engine I can't really take any useful lnformation from this.

The air filter is quite clean,so oil is not blowing in there.

 

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I cannot understand why turning the dipstick allows it to go in further, something wrong there. It just fits in a tube with a stop ring on the stick.

 

If oil is not getting in the air inlet, the oil has to be going via pistons/bores or valve stems or head gasket where the oil feed to the rockers comes through the head (unusual).

 

Yet it starts well, very confusing.

Valve stem seal wear usually  allows oil to pass on tick over, then when revved the oil burns but clears with a wide constant throttle. But if the compression is good and it starts well I would be very surprised if it is bore and piston/rings wear.

 

I would investigate the valve guides and seals first, in other words a head overhaul. at the same time the wear in the bores can be checked. 

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7 minutes ago, hider said:

I cannot understand why turning the dipstick allows it to go in further, something wrong there. It just fits in a tube with a stop ring on the stick.

 

If oil is not getting in the air inlet, the oil has to be going via pistons/bores or valve stems or head gasket where the oil feed to the rockers comes through the head (unusual).

 

Yet it starts well, very confusing.

Valve stem seal wear usually  allows oil to pass on tick over, then when revved the oil burns but clears with a wide constant throttle. But if the compression is good and it starts well I would be very surprised if it is bore and piston/rings wear.

 

I would investigate the valve guides and seals first, in other words a head overhaul. at the same time the wear in the bores can be checked. 

It is confusing! Under normal running you wouldn't think anything was wrong.Easy starting,and at canal speed no smoke.Even pushing it a bit on the river all seems normal.

However as I have said give it full throttle and the blue oil smoke it produces has to be seen to be believed.

Will reduce the excessive oil in the sump first to see if it has any effect. My theory being that the big ends are dipping in too high an oil level and flinging the oil into the undersides of the pistons,and although the rings should stop it getting into the combustion chamber, I have had an engine (in a motorbike) burn oil at high revs due to a failed scavenge pump allowing a build up of oil in the crankcase.+

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The crank will not be dipping into the oil with a small over fill, you would need gallons!

What oil are you using?

What size prop and gearbox ratio?

You say full throttle on rivers, that is rare with a canal boat, how big is it?

The 1500 D is not a powerful engine, with a worn one 27 HP would be good, fit for a 46 to 50 footer narrowboat on a canal at 4 MPH, not a 60 footer at 9 MPH on a river.

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34 minutes ago, hider said:

The crank will not be dipping into the oil with a small over fill, you would need gallons!

What oil are you using?

What size prop and gearbox ratio?

You say full throttle on rivers, that is rare with a canal boat, how big is it?

The 1500 D is not a powerful engine, with a worn one 27 HP would be good, fit for a 46 to 50 footer narrowboat on a canal at 4 MPH, not a 60 footer at 9 MPH on a river.

If it isn't an overfilled sump then valve seals or worn bore/pistons are the cause.

Boat is a 30ft steel narrowboat,prop is 16 inch pitch unknown.Gearbox is a Hurth I assume 2:1,although it might be 1.65:1.

I have never found it necessary to use full throttle,I only discovered the full throttle smoking by accident. Cruising along the Bridgewater canal,(20 miles and no locks) I got bored and just for the hell of it,opened it up.Was horrified by the amount of smoke and now that I am aware of it I can't really ignore it.If I hadn't done that I could well be cruising around in happy ignorance.

Oil used is Halfords 20/50

Edited by Mad Harold

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2 hours ago, Mad Harold said:

Thanks for you thoughts on this,but the smoke is blue, a hugh amount, you can't see the canal or towpath behind,it would be a credit to a warship dodging the enemy,and it stinks of,well,oil smoke.

Then you are burning oil, which is generally speaking bad news

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worn ring grooves in worn pistons in worn cylinders pump oil into the combustion space.....it is pushed out into the exhaust,where it partially burns when heat builds up...at low engine output,oil actually creeps along the exhaust surfaces and either forms a black tarry splatter all over ,or drips harmlessly into the water......if you have a wet exhaust ,you get the familiar rainbow effect. in the wake.......and greenies will hate you.....One tip......use an oil formulated for 2 stroke GMs,these oils burn a lot cleaner and without (much) smell......GMs burn lots of oil thats swept into the cylinders from the liner ports......another tip.......breathers into intakes are asking for a runaway........pipe the breather elsewhere.

Edited by john.k

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Just a thought, the crankcase breather is not blocked is it? If so it could blow more oil down the worn valve guides.

 

You could just have an oil soaked silencer...........................................

 

Edited by hider
duplicated

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