Black smoke?

[NorthwichTrader]

Ok, so engine is running and starting really well, BUT, under full power, I'm getting black smoke!

The liners/pistons/rings are new, and only run for around 3 hours without load, and 4 or so under load!

Somebody has suggested this is to be expected until everything had bedded in, namely, the piston rings have shaved the bores, etc.

The oil level is good!

Any thoughts?

[RLWP]

Black smoke is overfuelling. Oil smoke is blue - that's what you might expect until the rings have bedded in

 

What engine is this?

 

Richard

[Timleech]

Black smoke is overfuelling. Oil smoke is blue - that's what you might expect until the rings have bedded in

 

What engine is this?

 

Richard

 

 

Or bad combustion, most likely caused by dodgy injectors, though could be a timing issue if the engine has been worked on recently.

 

Tim

[RLWP]

Fair point Tim. Either way, it is unlikely to be piston rings or go away

 

Richard

 

MORE. Black smoke under full power. Did it do this before rebuild? It may be that the prop is way oversized to keep the engine revs lower

Edited October 1, 2014 by RLWP

[MtB]

My K1 doesn't have any smoke whatsoever under full throttle despite being very over-propped.

 

The exhaust is totally invisible under all conditions. Amazing really.

 

 

MtB

[Tam & Di]

Black smoke under full power. Did it do this before rebuild? It may be that the prop is way oversized to keep the engine revs lower

 

Engine is overloaded. Something round the blades? Shaft binding in some way?

[NorthwichTrader]

In tickover the boat cruises along at around walking pace, so I'm thinking it the prop size is OK????

It's a J3

I can hand-turn the shaft, so I don't think it's binding! I guess I should see what happens when I open it up in neutral?

It's a new rebuild and fitted in a new boat, so no previous history of performance!

I did roughly tune it in the engine shed, but haven't touched it since, on account I have some diesel leaks to get right first, plus it runs clear up to around half throttle? Could a poorly tuned engine run clear at low revs, that would be an interesting point?

Does the above give any further indicators as to the issue?

 

Ps nice one with your K1 MtB!

[nicknorman]

In tickover the boat cruises along at around walking pace, so I'm thinking it the prop size is OK????

It's a J3

I can hand-turn the shaft, so I don't think it's binding! I guess I should see what happens when I open it up in neutral?

It's a new rebuild and fitted in a new boat, so no previous history of performance!

I did roughly tune it in the engine shed, but haven't touched it since, on account I have some diesel leaks to get right first, plus it runs clear up to around half throttle? Could a poorly tuned engine run clear at low revs, that would be an interesting point?

Does the above give any further indicators as to the issue?

 

Ps nice one with your K1 MtB!

 

Black smoke is too much fuel or too little air. I guess it can also be due to bad injectors / timing * . Many older diesels (before the advent of pollution regs) allowed "over-fuelling" ie the injectors could dispense more fuel than the air supply allowed, so that if the load was greater than the max torque the governor would go to max fuel flow and then you get the black smoke.

 

With no load on (neutral) you will not get black smoke.

 

I would suggest checking the air supply in addition to the other things mentioned above - air filter etc (if it has one). And some diesels do have a butterfly valve on the inlet (no idea if your's does) so check that is opening fully.

 

However, re-reading your post and presuming the boat is propped the way I would like it - ie slightly overpropped so that the rpm can't quite reach the governed max - then I think black smoke at full throttle would be normal. Any time the governor goes to max fuel flow because the rpm set by the throttle lever is greater than the actual rpm, it is likely to give black smoke on an older design of engine. The solution is to not increase the throttle beyond the point where you get black smoke!

 

Ed: * because the bad injectors / timing reduces the efficiency of the engine, so more fuel is required to get the same torque, so the governor reaches max fuel flow before you might otherwise expect it.

Edited October 1, 2014 by nicknorman

[David Mack]

In tickover the boat cruises along at around walking pace

Walking pace is 3-4 miles per hour. How much faster are you expecting to go?

 

And how do you go slower than this when passing moored boats, or just held up by something ahead?

Edited October 1, 2014 by David Mack

[NorthwichTrader]

Many thanks, nickn., food for thought and makes me wonder whether I can improve things by adjusting the timing? If not, maybe get the injectors checked? There is a distinct possibility they might even be in the wrong heads, as there was unfortunately a big labelling mix-up with the head ancillaries? I wonder if there is any way of checking this?

[NorthwichTrader]

Walking pace is 3-4 miles per hour. How much faster are you expecting to go?

 

And how do you go slower than this when passing moored boats, or just held up by something ahead?

Hi David,

3-4 is perfect by us, we are in no hurry at all, and prefer the engine in slow mode, that's precisely what a kelvin means to us! If I want to go slower still, I can put it into neutral once and a while, same when waiting around!

I used the tickover/walk-rate point, just to give some indication of the prop-sizing, just in case it meant something to someone??

I use the throttle turned up to get out around some incredibly tight turns at Saul Junction, especially from the marina entrance on the Stroud arm, out into the main Glouc & Sharpness canal! The wind can often be against you too at the same time!

This is when I'm blowing the black smoke!

[David Mack]

Hi David,

3-4 is perfect by us, we are in no hurry at all, and prefer the engine in slow mode, that's precisely what a kelvin means to us! If I want to go slower still, I can put it into neutral once and a while, same when waiting around!

I used the tickover/walk-rate point, just to give some indication of the prop-sizing, just in case it meant something to someone??

I use the throttle turned up to get out around some incredibly tight turns at Saul Junction, especially from the marina entrance on the Stroud arm, out into the main Glouc & Sharpness canal! The wind can often be against you too at the same time!

This is when I'm blowing the black smoke!

I was just thinking that if tickover gives you normal canal speeds then you are overpropped. A nice engine note at that speed, but if you open her up much more then perhaps the engine is overloaded, amd hence the black smoke.

[NorthwichTrader]

Ah, OK, thanks, David! Maybe this is the issue, then? I honestly don't know what to expect, it's all very new to me!

I do know the boat has a deep draught, and at 70ft maybe the engine is struggling? The rpm's do wind in very easily though?

[NB Alnwick]

Ah, OK, thanks, David! Maybe this is the issue, then? I honestly don't know what to expect, it's all very new to me!

I do know the boat has a deep draught, and at 70ft maybe the engine is struggling? The rpm's do wind in very easily though?

 

Our K3 has been pushing our boat around for almost 20 years without major work. We get a bit of oil smoke if I push it really hard - mostly as a result of excess oil being drawn down the valve stems from the rocker boxes but we have never seen black smoke from the exhaust - the J and K series engines were designed to burn extremely lean and clean. As has been said already, black sooty smoke results from an excess of fuel or lack of oxygen in relation to the amount of fuel injected. My first check would be to make sure that the engine air supply is all correctly assembled and not restricted in any way. Similarly, a restriction or blockage in the exhaust could have a similar effect. if the air can get in and the exhaust can get out freely, then it may be an issue with the fuel injection side.

 

Just to be sure about prop size, it is worth putting a piece of luminous tape on the flywheel and using a hand held electronic rev-counter to measure the speed of the engine compared to boat speed through the water. At walking pace (3-4 mph) the engine should be somewhere in its mid-range of revolutions - between 350 and 500 rpm. If you are achieving 3-4 mph at much less than 350 rpm the boat is probably over-propped. Our prop size was reputedly reduced from 26" to its present 24" after Phil experienced similar problems in 1997.

[NorthwichTrader]

Many thanks, NBA, I'll do a measured mile to check the rpm. It's obviously deep water in the Glouc & sharpness canal, which I understand can increase the mph somewhat? Could be wrong?

Also, re the air intake, would you agree there's nothing else to check, other than the alignment of the slots over the rocker cover? I do know the carb mesh is occluded, but I'm guessing this wouldn't affect the diesel performance?

The exhaust's internal bore measures 4.1cm and is already showing a lot of carbon deposits at the exit point in the roof! The exhaust note has a very distinct huffing sound, not dissimilar to that of a steam train.

[MtB]

Given you're so close to RW Davis who built your boat and and they know about Kelvins, why not ask then to sort it out?

 

Or have you ruled them out for some reason?

 

MtB

 

 

 

 

Edit to fix the spelling.

Edited October 2, 2014 by Mike the Boilerman

[NorthwichTrader]

I've just read KW's article on fitting a J3, and he mentions 2 1/2" bore, where mine isn't even 1 1/2"!

I'm sure the exit hole from the exhaust manifold isn't 2 1/2" though?

[Timleech]

I've just read KW's article on fitting a J3, and he mentions 2 1/2" bore, where mine isn't even 1 1/2"!

I'm sure the exit hole from the exhaust manifold isn't 2 1/2" though?

 

The installation drawings show 1 1/2" bore.

That is for a wet exhaust, though.

 

Tim

Edited October 2, 2014 by Timleech

[NB Alnwick]

I've just read KW's article on fitting a J3, and he mentions 2 1/2" bore, where mine isn't even 1 1/2"!

I'm sure the exit hole from the exhaust manifold isn't 2 1/2" though?

 

Our exhaust is 2.75" - bigger engine (twice the capacity but it doesn't need to work as hard) and it also huffs like a steam train from the outside but in the engine room there is far too much mechanical clatter to hear the exhaust.

 

Edited to add that I would take the boat back to R W Davis - Phil would not be happy to see one of his boats making a dirty exhaust . . .

Edited October 2, 2014 by NB Alnwick

[gbclive]

I've just read KW's article on fitting a J3, and he mentions 2 1/2" bore, where mine isn't even 1 1/2"!

I'm sure the exit hole from the exhaust manifold isn't 2 1/2" though?

Would appreciate were to find this article - thanks.

 

BTW your Kelvin learning curve and various issues mirror very closely my own with a J2 which has recently had a major top end overhaul at RW Davis.

 

Excellent progress recently, but it took a lot of time and effort post overhaul by Phil and his team.

 

Overheating completely cured by a new thin baffled skin tank on the outside of the swim replacing a deep, un-baffled one against the bottom of the hull?

 

Very uneven idle with alternating light and dark smoke now much better but no single cause identified - timing and regulator adjusted.

 

Exhaust above the roof sawn off so that the considerable soot lining could be scraped cleaner.

 

Originally over-propped with a 20 x 16 - very limited on revs and felt choked when winding in any significant throttle. After some advise from this forum (thank you) I tried to have 3 inches taken out of the pitch (logistically difficult) then tried to replace it with a 20 x 13 but could not find one. Settled for a 19 x 14, however it now seems perhaps just a tad too fine. Boat is about 64 foot, so the baby J has quite a job to do.

Used an optical tacho and Speedpro+ gps app for the iPad to quantify things:

225 rpm now gives 1.9 mph in the deep still water.

340 gives 2.8

470 gives 3.8

670 gives 5.2 (engine getting quite lively!)

790 gives 5.9 (that's when I chickened out - mayhem!).

Max rpm quoted at 1000 to get the full 22HP.

 

Of course on more normal narrow and less deep canals, the speeds will be less.

 

Just a sense that a little more thrust would be nice against the flow in rivers and against strong headwinds, but overall the engine seems much more comfortable with less prop.

 

Also had a number of diesel leaks from from various joints.

 

Off to work now to pay for it all?

[NorthwichTrader]

Hi Clive,

If you PM me an address I can get a copy of KW's article to you!

If you're still in the area, we can catch-up at the marina?

All the best,

Stuart

[gbclive]

Hi Clive,

If you PM me an address I can get a copy of KW's article to you!

If you're still in the area, we can catch-up at the marina?

All the best,

Stuart

Thanks Stuart - will do.