Excessive Smoke at high power

[cuthound]

12 hours ago, Mike the Boilerman said:

 

Some history is always helpful. Has it always done this? If not, how did it start? Suddenly? or slowly and progressively?

 

 

 

See post #21.

 

"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"

[MtB]

1 hour ago, cuthound said:

 

See post #21.

 

"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"

 

Ah missed that. In that case I'd say there is nothing wrong with engine and it is just over-propped.

 

Power rises with the cube of the shaft speed IIRC, so a blade can work fine in most of the rev range and only overload the engine right at the top of the range.

 

[cuthound]

2 minutes ago, Mike the Boilerman said:

 

Ah missed that. In that case I'd say there is nothing wrong with engine and it is just over-propped.

 

Power rises with the cube of the shaft speed IIRC, so a blade can work fine in most of the rev range and only overload the engine right at the top of the range.

 

 

But according to the OP the smoke is blue, not black, which is indicative of burning lube oil, rather than over fuelling.

 

Something ain't right, that's for sure.

 

[Tony Brooks]

2 hours ago, Mike the Boilerman said:

 

Ah missed that. In that case I'd say there is nothing wrong with engine and it is just over-propped.

 

Power rises with the cube of the shaft speed IIRC, so a blade can work fine in most of the rev range and only overload the engine right at the top of the range.

 

You may well be correct in the above but I think it is also resistance to the hull moving through the water. More likely is that the torque (twisting force) starts falling while the power continues to increase. When the torque is no longer enough to turn the prop the engine overloads as explained above.

 

I find exhaust smoke colours rarely  completely match the theoretical colours so would not rule ot an oversized prop.

[RLWP]

5 hours ago, cuthound said:

 

See post #21.

 

"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"

The other obvious explanation is the 'Italian tune-up'. Take an engine that usually chugs about doing not-a-lot and give it a good thrashing. You get lots of smoke, soot, clag, crap and the like until the engine cleans itself. Can take quite a while to burn stuff out of the exhaust

 

Richard

[Rickent]

10 minutes ago, RLWP said:

The other obvious explanation is the 'Italian tune-up'. Take an engine that usually chugs about doing not-a-lot and give it a good thrashing. You get lots of smoke, soot, clag, crap and the like until the engine cleans itself. Can take quite a while to burn stuff out of the exhaust

 

Richard

Take more than an "italian tune up" to sort my smokey old beast out. 

[Mad Harold]

6 minutes ago, RLWP said:

The other obvious explanation is the 'Italian tune-up'. Take an engine that usually chugs about doing not-a-lot and give it a good thrashing. You get lots of smoke, soot, clag, crap and the like until the engine cleans itself. Can take quite a while to burn stuff out of the exhaust

 

Richard

That sounds like an easier option.

When first glancing at your post,I thought you were going to tell me about "The Mexican Valve Grind"

I'me sure you know what that is, but for those that don't.

Remove valve springs,secure valve,insert valve stem in electric drill and spin in the drill maintaining upward pressure.

 

 

 

[cuthound]

26 minutes ago, RLWP said:

The other obvious explanation is the 'Italian tune-up'. Take an engine that usually chugs about doing not-a-lot and give it a good thrashing. You get lots of smoke, soot, clag, crap and the like until the engine cleans itself. Can take quite a while to burn stuff out of the exhaust

 

Richard

 

I know, BT policy was to test each standby generator on load for one hour each month, but many of their cost & risk conscious ops managers used to test their standby generators off load for 5 minutes a month ?.

 

I ran a project to prove that each of the 6500 BT standby generators was "millenium ready" by effectively re-commissioning them (12 hour test to a dummy load, with110% rated load start and remainder at 100% rated load). Lots of smoke a d quite a few exhaust fires Resulted in ops managers having to prove they were testing gens for an hour a month on load.?

Edited June 7, 2019 by cuthound
Clarification

[RLWP]

1 minute ago, cuthound said:

 

I know, BT policy was to test each standby generator on load for one hour each month, but many of their cost & risk conscious ops managers used to test their standby generators off load for 5 minutes a month ?.

 

I ran a project to prove that each BT standby generator was "millenium ready" by effectively re-commissioning it (12 hour test to a dummy load, with110% rated load start and remainder at 100% rated load). Lots of smoke a d quite a few exhaust fires Resulted in ops managers having to prove they were testing gens for an hour a month on load.?

You have all the fun!

[cuthound]

8 minutes ago, RLWP said:

You have all the fun!

 

It was fun, we broke the crank on one old generator and had one old Blackstone  overspeed (they had fuel lines inside the crankcase) because no one checked the oil  for level or fuel dilution. Fortunately one of the test team managed to stop it by discharging a CO2 fire extinguisher into the air inlet before it ran away.

 

Found loads of sites wirh cooling issues where a building security uplift programme run by the estates people had put grilles over the generator room air inlet louvres, reducing the amount of air meeded for cooling and aspiration.

Edited June 7, 2019 by cuthound
Spillung

[john.k]

Anyway,you haven seen smoke till youve seen one of the old Clyde GM locos of the NSW  Railways sit for half a day idling at the old Coopers Plains yard,then take off for home with a long train of empties......it would take all day for visiblity to return .

[RLWP]

14 hours ago, Mad Harold said:

That sounds like an easier option.

 

 

 

I wasn't suggesting that is what you go and do, I was saying that is what you did. You worked the engine hard for a change and disturbed years of stuff in the exhaust

 

Richard

[bizzard]

Also I think Mad H said that his boat was a 30' boat in which case a 1500 BMC is loads of power and until he opened up on the Bridgewater and put a decent load on the engine and got the exhaust sytem nice and hot ''and the blue smoke began as it burn't accumulated oily goo from the exhaust system

''which it wouldn't really do idling along at canal speed in that boat. I reckon if he'd carried on at high speed for some time it would have cleared. My boat is only 34' long with a Lister ST2 about 19 hp which for most of the time I go along at canal speed at moreorless just a fast idle revs under light load. If there's no one about I sometimes open it up and it will do the ''Make smoke'' big time, black and blue with a display of fiery sparks from the exhaust to boot which will eventually clear. I sometimes tow boats which puts a decent load on it which does it good.

[LEO]

On a previous boat I had a 1.5 BMC, if I filled the oil to the correct level on the dipstick it would discharge oil via the crankcase breather and the rear crankshaft oil seal, then when it had reached the 'correct' level it would run happily for hours, overfill it and the oil would be discharged as before. I used to top it up to between the high and low mark on the dipstick and it was 'happy as Larry'.

 

You also state you use a 20/50 multigrade - I thought and old engine like a BMC would have preferred a straight Sae30......

 

M.

[RLWP]

5 minutes ago, bizzard said:

I reckon if he'd carried on at high speed for some time it would have cleared

Agreed

 

Richard

[bizzard]

Just now, RLWP said:

Agreed

 

Richard

What he could try without speeding along is to find a convenient post or tree perhaps on a bend in the canal and tie the back of the boat to it with a long rope so that the boat can run stationary on a lot of throttle for a long period in mid stream to see if the smoke clears and checking the engines oil level before and after the experiment to see if it burned much oil in the process.

[RLWP]

1 minute ago, bizzard said:

What he could try without speeding along is to find a convenient post or tree perhaps on a bend in the canal and tie the back of the boat to it with a long rope so that the boat can run stationary on a lot of throttle for a long period in mid stream to see if the smoke clears and checking the engines oil level before and after the experiment to see if it burned much oil in the process.

Easier to nose the boat into the bank, or do this in a lock

[bizzard]

1 minute ago, RLWP said:

Easier to nose the boat into the bank, or do this in a lock

Yes, better still.

[bizzard]

31 minutes ago, LEO said:

On a previous boat I had a 1.5 BMC, if I filled the oil to the correct level on the dipstick it would discharge oil via the crankcase breather and the rear crankshaft oil seal, then when it had reached the 'correct' level it would run happily for hours, overfill it and the oil would be discharged as before. I used to top it up to between the high and low mark on the dipstick and it was 'happy as Larry'.

 

You also state you use a 20/50 multigrade - I thought and old engine like a BMC would have preferred a straight Sae30......

 

M.

Yes before multigrade oils it would have been 30 grade in summer and 20 in winter. 20/50 superceded it which would be fine.

[cuthound]

25 minutes ago, RLWP said:

Easier to nose the boat into the bank, or do this in a lock

 

If he ties the boat up and runs it flat out in an empty lock he might choke himself before then smoke clears! ?

[RLWP]

21 minutes ago, cuthound said:

 

If he ties the boat up and runs it flat out in an empty lock he might choke himself before then smoke clears! ?

Best if this is done in a full lock...

[john.k]

We used to burn out oil fouled mufflers with the oxy /acetylene......start the fire in one end,depress the oxy lever ,shut offf the fuel gas.....and a ring of red hot and a 10 foot flame will shootout the end of the exhaust.....the redhot ring will travel along the exhaust as the goo burns out......be prepared for bulk smoke ,tho.......Dorman  6 DL powered gensets were notorious for fouling ,and then catching fire.

[Mad Harold]

35 minutes ago, RLWP said:

Best if this is done in a full lock...

That's what I am going to do (when it stops raining) Will report back on result,hopefully with an intact engine!

All the replies on this thread have been carefully noted,and I am most grateful to all the people who have given my problem some thought and replied.

Thank you all.

[Guest]

1 hour ago, RLWP said:

Best if this is done in a full lock...

But not in a tunnel

Many moons ago I had an Escort van which burned more oil than petrol. After fitting a new(er) engine,there was an alarming amount of blue smoke from the existing exhaust especially if you got your clog down a bit. It was some time before it stopped this, which made me think that the replacement engine was at fault. Does sound like the BMC in question could be burning off surplus gunge in the exhaust. 

Sounds like a river trip would do it good?

Edited June 8, 2019 by Guest

[TheBiscuits]

23 hours ago, catweasel said:

Sounds like a river trip would do it good?

That's a good idea, but if @Mad Harold's nearest river is the Calder and it's been raining hard, he probably wants to make sure his engine is OK before going out on it!