Do all engines have a hint of blue smoke ?

[alec]

Over the winter I have noticed in the marina, that all diesels engines seem to have a hint of blue smoke .

Like myself, owners come down to their boats, crank the engine and give them a run in gear for half an hour or so. There is the initial black smoke on startup then they settle with a touch of blue in the exhaust.

Or am I just seeing things because of the cold air ?

Regards,



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[steve_cronin]

A simple device like a marine diesel will shove out a little incompletely burned diesel at initial startup as did roadgoing diesels a few years ago before emissions became as important eco-issue as they are now.

if it is just a blue haze until working temp. is achieve it is more healthy than a cause for concern.

It isn't a good idea for diesel pistons to skit up and down with nil load otherwise a phenomenon known as "Bore Glazing" can occur which will bring about a loss of compression and ring overheating so if you're in a position to pull against something instead, like the harbour wall, this is to be recommended.

Have a peaceful Sunday evening (or what's left of it)

Steve Cronin

<hr width=100% size=1>The above is, like any other post here, only a personal opinion

 

[Heckler]

as a general rule a diesel engine in really good health will not emit blue smoke, it can be caused by wear in the engine, and it is lube oil burning or injectors that need cleaning and setting, it is normal in engines that have done quite a few hours. it is not a problem unless loads of lube oil is being consumed or, if the prob is with the injectors, bad starting or loss of power. the smoke will be worse on cold start up because in the case of bad injectors the fuel is not combusting efficiently and in the case of wear the engine parts have not expanded to form better seals.
think about it, a brand new diesel car, blue smoke on start up?
by the way during my time as a head of maintenance for an oil explorer major i have rebuilt and supervised more rebuilds of diesel engines of all shapes and sizes than you can shake a stick at and i have never diagnosed an engine as suffering from bore glazing!! i have rebuilt engines and "busted the glaze" on the cylinders so that new pistons and rings could bed in metal to metal, but the glaze is a natural consequence of many hrs of running.
stu



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[webcraft]

Bore glazing

I always suspected this was a bit of a non-problem for most marine diesels . . . is it more of a concern with new engines?

I can't believe it's a problem with my 31 year old Volvo, and regularly leave the engine ticking over as a precaution as I sail through tricky spots in flukey winds.

Should I worry?

- Nick




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[Heckler]

Re: Bore glazing

its an old wives tale and urban myth
stu

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[Gunfleet]

2 year old VW no blue smoke. Am I missing something or is Sonsy right? Only my boat smokes (I gave up years ago)

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[ongolo]

Hi all,

Only slighly ill engines produce smoke. white smoke indicates injector or injector pump problems and while combustion is incomplete due to low engine temperature, blue smoke indicates oil consumption for whatever reason and black too much diesel injected for the amount of air available, a short emmision of black smoke for .5sec or so is normal during drastic load changes until the governor/delivery rack has itself adjusted to new conditions.

regards ongolo


<hr width=100% size=1>1000 dream about it, 100 talk about it, 10 start and 1 completes it

 

[supermalc]

Regarding cylinder glazing. This was never an issue with cast piston rings, however chrome rings can glaze a bore on a new, or reconditioned engine. I first came across it a few years ago, when a friend with a garage fitted an engine that had been reconditioned. After leaving it idling for a while, common practice with newly rebuilt engines it smoked very very badly. The engine firm came out, took it up the road and ...... no smoke. Unknown at that time to us, it needed glaze busting which I think simply means puttiing 'Brasso' for want of a better explanation. in the intake with the engine running. Engines with chrome rings require hard work from the off, untill they bed in.

We 'live and learn' as they say.

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Take a look at my boating pages.

 

[oldharry]

First off, the blue smoke you have noticed is very common with diesels that have stood unused for a while, and then run on light load, or off load. Any engine that is at all slow to start will pump unburnt atomised fuel into its exhaust system where it settles until the system gets hot enough to burn it off. It appears as blue/white smoke. An engine that produces black or white smoke at start up will be particularly prone to this. It is not indicative of anything wrong other than lack of use, and possibly slight wear, but nothing to worry about.

Second - bore glazing is not an 'urban myth', and it does occur in mistreated engines. Diesels need to work reasonably hard for at least part of their duty cycle, otherwise combustion and oil products form a hard glaze on the bore which prevents the rings from seating properly, and causes increased oil consumption and blow by.

A diesel being run regularly just to charge the batteries without proper loading can suffer all kinds of problems, bore glazing being just one. And yes I KNOW that some owners get away with it. But beleive me, others do not. Prolonged tickover is not damaging to the engine provided it is mixed in with spells of hard work. Offshore anglers roaring home from a days fishing are not just in a hurry to get back to the pub, they are actually working their engines up to clear the accumulated effects of several hours of trolling. They know that if they do not do this their engines will soon lose reliability, power, become difficult to start, will produce increasing amounts of smoke (not nice for the punters!), and in the long term will need full and expensive overhauls to deal with bore glazing and the like. So a good hard thrash for an hour or two on the way home clears out all the carbon from the combustion chambers, valves and exhausts, burns off any unburnt fuel in the exhaust, brings all parts of the engine up to working temp so that the lub oil flushes it all through properly, burns off any volatile fractions in the lube, and disperses any moisture in the manifolds so that corrosion to the engine internals - particularly the valve springs - is avoided. And when you earn your living using a diesel at sea, beleive me you take care of it!

My local garages' most disliked customer is the local vicar. He runs a diesel car, which he NEVER drives at more than 30 MPH, usually for only 2 - 3 miles at time. Every few weeks he comes in complaining of poor starting and smoke. Geoff simply thrashes it down the motorway for 20 - 30 miles, and hands it back running sweetly - together with the bill!

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[TonyBrooks]

Re: Bore glazing

No.

I have in my posesion a number of papers (supplied by Lister Petter) concerning bore glazing. From these and observations I think it reasonable to conclude that:

1. Some engines are more prone to it than others.

2. There is an issue over bore galzing & lightly loaded engines.

3. The geometory of the piston, above the top ring has much to do with a particular engine's suceptability to it.

4. The quanitity of the additive pack in the lubricating oil tend to eb a major influance.

5. The fuel can have an influance, but will probably not be a major factor if running on "reputable" gas oil or derv.

I would advise ensuring you know the recomemnded SAE spec given by the MARINISER for the lube oil of your engines and taking some trouble to obtain it. Do not get persuaded that a higher spec is better oil - it just has a higher performance, which you may well not need.

I strongly suspect that marine engines (MD2 & Bukh type engines) and old UK/european vehicle and industrial designs tend to be most resistant, whilst modern Jap. "high speed" insustrial based units will be less resistance - hence my emphatic no for the Volvo.

I have mixed feelings about brasso down the air intake, but it must be worth a try, espacially if folowed by a flush and oil change and a carefull "redex decoke".

Tony Brooks

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[oldharry]

True 'glazebusting' is done with a special tool which effectively roughens the bore slightly to allow the rings to bed in. The angle at which the bore is honed out in glaze busting is fairly critical for success. Indeed incorrect honing can make a bad engine worse and actually increase oil consumption.

Brasso or other abrasives injected down the intakes is definitley not going to acheive that..... !

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[steve_cronin]

Without personally experiencing the events posted it is not possible to generalise. Always a problem here. Smoke can be either diesel or oil burning. Let's not fall out over it.

Steve

<hr width=100% size=1>The above is, like any other post here, only a personal opinion

 

[oldharry]

Agreed Steve. The original post asked why diesels left running in the marina always seem to produce a blue haze.

I would only fall out over it if its the bloke in the berth upwind from me....

Take it or leave it, but when your livelihood has depended on keeping diesels running sweetly, you do get to see and know most of the faults that can befall diesels - if not at first hand, then on the next blokes boat. And thats knowledge I am quite happy to pass on.

Smoke from the boat could equally well be me enjoying a pipefull of St Brunos best.... and just as obnoxious as anyones diesel, according to SWMBO!

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[steve_cronin]

Being brought up with engines both diesel and petrol ( my child's comforter was a Jowett Bradford crankshaft!) and ahving a father who was timed served at Fords and Perkins Peterborough, I've always looked after my own engines big or small.

It's difficult to diagnose from a few words on here but we're agreed that it is one thing or the other (& probably a combination of both?) but it is rare, don't you agree, for a marine diesel to have completely clear omissions all of the time. In some marinas, my last one was Port Hamble, just one engine running can fill the place and especially down below in a yacht with nasty smells and worse. Why do people do it?

Steve Cronin



<hr width=100% size=1>The above is, like any other post here, only a personal opinion

 

[Guest]

Wind direction....

When my engine starts - which it doesn't want to do at moment !!

I first check wind direction, advise all downwind that smoking is bad for your health, press starter. That is the last I see of anything astern of me for a good 3-4 minutes.
Warm her up and she settlews down to a trickle of white smoke until opened right up where she emits black smoke.

So what do I know .... a) she is old and tired with poor compression and I guess isn't getting full share of fuel at low revs, b) she is getting too much that cannot be burnt off at full revs.

When motoring she likes 1/3rd throttle - seems to sit nice and sweet at that, little smoke, no vibration and chugs along all day. Less than that and its blue tinged. More than that and it darkens ....... Oh I forgot to say that acceleration on this is amazing ..... and prop unloads so quick !!!

But a 32hp in a 25ftr ...... is so overpowered that I don't need full power .... If I prop correctly - she would swing her arse so hard on prop walk !!!! NO she's ok ......

Just have to get her started though !!!!


<hr width=100% size=1>Nigel ...
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[Guest]

Re: Bore glazing

I chuck all sorts down my tank ..... gash diesel others don't want, injector cleaner by the bucket full, bit of kero here and there to give it a spike .... but not Biocide yet !!!!

But of course mine's an old 4-99 Perkins Bus engine from the 50's .....


<hr width=100% size=1>Nigel ...
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[Heckler]

glaze busting

means using a honer with rapid up,down and turning movements in the cylinder to leave microscopic "scores" on the liner. i have used fine dead wet and dry paper as well.
to talk about putting brasso in a running engine is as daft in my opinion as my old man who used to buy that gunge they used to sell in the 60s "to stop your engine burning oil"
it didnt
stu

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[robind]

Has anyone heard of "Vimming" this was the practice of warming the offending (smoking ) diesel engine up and at about threequarters throttle introducing through the air intake filter housing a tin of Vim. this was usually done progressivly and at sea and on engines without turbo`s (for obvious reasons). the result was usually quite good for a while,

I wouldnt reccomend it (in the long term.or for reasons of pollution)

Rob

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[Col]

Lunacy!
Anything abrasive will get stuck in ring grooves and carry on, erm, abrading! - untill engine too worn too work.
Also abrasive residues will find their way into the oil, and scour away at your bearings.

Please, Please, Do not even think of doing this to your engine no matter how bad it is.
You will simply hasten its demise.

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[supermalc]

Just in case anyone has misunderstood my post, regarding 'Brasso' I DID NOT say put Brasso in the engine. I said a glaze busting powder is sometimes used if a newly reconditioned engine has been idling when first started, and the chrome rings have glazed the bores.

Sorry for any misunderstanding. I cannot confirm what is used, as my friend who told me sadly died of a heart attack about 5 years ago. He was an agricultural engineer, working on Tractors for all his life, and one of the best in his field (please excuse the pun)

<hr width=100% size=1>Malcolm.
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Take a look at my boating pages.