White smoke then black smoke (BMC 1.8)

[Dave_P]

As is common on these engines, I've always had a bit of smoke on start-up which soon clears. Then I would get a small amount of white/grey smoke if I really needed to rev hard, nothing to speak of though.

 

Now when I rev hard I'm getting a constant plume of white smoke which then goes black if I rev even harder. This is in both forward and reverse and is noticeably different to before.

 

If it was just the white then I'd assume piston wear, but why such a sudden change and why does it goes black when I rev flat out?

 

Any thoughts?

[peterboat]

white smoke is normally quenched combustion, black smoke is either diesel or oil being burnt

[Tony Brooks]

Its cold today so depending upon how the "smoke" behaves it might be steam.

 

Black means unburned fuel so how does it idle? maybe an injector is dribbling or just producing jets instead of droplets.

 

You might have something around the prop or an oversized prop causing the engine to overload and make black smoke.

 

I do not understand how piston wear can produce white smoke all the time, maybe on starting because of loss of compression but not once its running and warm.

[Athy]

Has a new Pope been elected?

[bizzard]

Its cold today so depending upon how the "smoke" behaves it might be steam.

 

Black means unburned fuel so how does it idle? maybe an injector is dribbling or just producing jets instead of droplets.

 

You might have something around the prop or an oversized prop causing the engine to overload and make black smoke.

 

I do not understand how piston wear can produce white smoke all the time, maybe on starting because of loss of compression but not once its running and warm.

Steam!!, steam's invisible and extremely hot, but of course Tony I know what you mean, more likely water vapor.

Edited February 12, 2016 by bizzard

[Mac of Cygnet]

Has a new Pope been elected?

Well they thought he had, but he backed out. Not surprising really.

[Bee]

If it was mine I think I would see a diesel specialist and have a chat about pumps and injectors, white smoke can be too retarded, black smoke can be overfuelling. If it has only just started happening its unlikely to be pistons/valves/mechanicals unless something has gone bang. oil and water ok?

[RLWP]

As is common on these engines, I've always had a bit of smoke on start-up which soon clears. Then I would get a small amount of white/grey smoke if I really needed to rev hard, nothing to speak of though.

 

Now when I rev hard I'm getting a constant plume of white smoke which then goes black if I rev even harder. This is in both forward and reverse and is noticeably different to before.

 

If it was just the white then I'd assume piston wear, but why such a sudden change and why does it goes black when I rev flat out?

 

Any thoughts?

How is the water level?

 

Richard

[Dave_P]

It's not steam or water vapour. It's not prop related as it happens just the same in neutral.

 

Haven't checked the water level. Will have a look later when the engine has cooled.

[RLWP]

It's not steam or water vapour. It's not prop related as it happens just the same in neutral.

 

Haven't checked the water level. Will have a look later when the engine has cooled.

 

Check your air filter while you are in there

 

Richard

[Dave_P]

 

Check your air filter while you are in there

 

Richard

Ok boss. Oil level too?

[RLWP]

Ok boss. Oil level too?

 

If you want...

 

A clogged air filter will not pass enough air at higher engine speeds - black smoke

 

Richard

[Dave_P]

 

If you want...

 

A clogged air filter will not pass enough air at higher engine speeds - black smoke

 

Richard

I pulled out the air filter. My fingers are now black. I'll get a new one and see what happens. Not until next week though, I've got a dirty valentines weekend away to enjoy first.

 

Thanks for the advice so far.

[RLWP]

Welcome to the black-hand gang.

 

Now, ours was really, really black after the silencer got a hole in it

 

Richard

Edited February 12, 2016 by RLWP

[Dave_P]

Welcome to the black-hand gang.

 

Now, ours was really, really black after the silencer got a hole in it

 

Richard

I used to work with a guy who, when confronted with a dark place, would proclaim it's blackness by comparing it to a 'part' of a nun/witch. The two were interchangeable.

 

That's how black my fingers got.

[RLWP]

That is very black

 

But not as black as a priest's socks

 

Richard

[Higgs]

As is common on these engines, I've always had a bit of smoke on start-up which soon clears. Then I would get a small amount of white/grey smoke if I really needed to rev hard, nothing to speak of though.

 

Now when I rev hard I'm getting a constant plume of white smoke which then goes black if I rev even harder. This is in both forward and reverse and is noticeably different to before.

 

If it was just the white then I'd assume piston wear, but why such a sudden change and why does it goes black when I rev flat out?

 

Any thoughts?

 

 

I once had to thrash my 1.5, in reverse, to avoid a collision. The exhaust gas was very dark. At all other times but extreme throttle, only happened once, the smoke is pretty much invisible. I put the dark exhaust down to the engine not burning the fuel fast enough. I don't know if that in itself is a symptom of a serious problem, but the engine ticks over well and otherwise causes no concern.

[MtB]

I used to work with a guy who, when confronted with a dark place, would proclaim it's blackness by comparing it to a 'part' of a nun/witch. The two were interchangeable.

 

 

Known amongst particle physicists as, I believe, a 'black hole'...

 

It's not steam or water vapour. It's not prop related as it happens just the same in neutral.

 

 

Does the black smoke also happen in neutral?

[alan_fincher]

I pulled out the air filter. My fingers are now black. I'll get a new one and see what happens.

You have a BMC with an air filter that actually does anything?

 

I might have liked to have had one of those!

[MtB]

Don't people take them off because they keep getting blocked??!

[RLWP]

Don't people take them off because they keep getting blocked??!

 

No, Sir

 

Richard

[MtB]

Why are they always missing then!

[RLWP]

This 'always' you speak of

 

Richard

[MtB]

None of the BMCs I've ever got up close and personal with have had an air filter.

 

Or rather, neither of them....

[Dave_P]

 

 

Known amongst particle physicists as, I believe, a 'black hole'...

 

 

 

 

Does the black smoke also happen in neutral?

Yes