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Diesel injector seals

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Hi guys. , on my ruggerini rm278 after a rebuild by a professional , my injectors had 2x .5 mm one side. And 1mm the other !   My book says use .5 mm. , , when I replaced the nozzles all the shop had was 1.5 ,    , so atm I have 2mmNot right I know , it’s running well but light grey smoke ,  .does anyone know what difference the size makes as to smoke ? . Will.5 give less unburned  diesel which I appear to be getting ,,,,,. 

atm  as we have no timing marks. I’m running with feeler gauges under the fuel pump to simulate shims till I get a sweet spot , not ideal but works ,   Cheers guys.  

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At any given delivery rate and pressure I would expect a smaller nozzle to atomise the fuel more finely so it catches fire more easily and the droplets burn out faster. However this assumes single hole nozzles that are comparatively rare in today's narrow boat engines. I THINK multi-hole nozzles will be the same but Pintle and Pintaux nozzles may not lift as far with a larger "hole" so may be more tolerant of size differences. I have no idea what type of nozzle your engine uses.

 

 

The volume/amount of fuel delivered will be set by the injector pump not the nozzles so I doubt its over-fueling. Droplet size is important to how the fuel ignites and burns.

 

Sorry, just seen you are talking about seals, not nozzles. Frankly I cant even imaging a 0.5mm seal unless its the soft washer the injector sits on.

 

If it is a thicker one will slightly alter the compression and put the spray into a slightly different place in the combustion chamber but suspect it would not make a major difference and a seal can in no way alter the fuel delivery.

 

Please can you clarify what you are referring to?

Edited by Tony Brooks

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Hi tony . Sorry not been on here for a while , I’m back to square one at the moment , , yes I mean the copper washers the injector sits on , I have read that this height can drastically alter smoke amounts , , the book says use .5 mm washers. ,  , but we have 1.5 mm in now , however the head has been skimmed , , we thought was a temp problem but I don’t think so now , as the water pump just packed in and we ran for quite a while with no pump and still smoked. , any help appreciated , 

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Skimming a head with an absolutely flat mating face will not affect the compression or compression ratio, skimming the block will.

 

I still can't see the copper sealing washer thickness making a major difference but you said you have two 0.5mm washers. just heat these to cherry read and let them cool. that will soften them for reuse.

 

Is this a direct injection engine or indirect. If direct then it may smoke a bit under light loads, at idle and at low speed.

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It is a 25 year old marinised Italian tractor engine  1250 2 cylinder ,,  we had the head stripped new liners and bores as my engine man said this was why it smoked. ,very pale blue /grey , even on tickover ,  so we are £2000 down and engine still smokes , , it is not real bad. But more than most boats I have seen , quite a strong smell, , chap from key diesel looked and though fuel issue as it runs good. Sounds good 

, we assumed it wasn’t burning the diesel due to low head temp , but with the water pump just failed  and smoke still present this can’t be the case , as I said book says use .5 mm copper seals under injectors. , when we did strip , one side had a 1mm.  Other. Two .5 mm. , we replaced with 1.5 mm , , , we still have light grey smoke on all revs and even tickover , I’ve altered timing several times and has no difference ,,  someone else suggested a partially blocked car boned up exhaust ,   , we do have a bit of black soot on exhaust , as we have a90 degree bend pushed into outer exhaust hole to steer smoke away from rear of boat 

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It could be a partially blocked exhaust but bluish smoke usually indicates burning oil that would be normal after what sounds like a major overhaul but I note no mention of new pistons to match the new liners. If you do have old pistons and rings in new liners its asking for oil burning. It may or may not get   better as things bed in.

 

I suspect it is a direct injection engine and they smoke at low speeds and powers because the swirl in the combustion chamber during combustion is not fierce enough to move more oxygen onto the burning fuel droplets. That would tend to cause greyish smoke on starting and the more blackish.

 

As most boats use indirect injected diesels its not surprising they smoke less. Indirect injection was developed to give a cleaner burn at low speeds and powers.

 

Lets have a photo of the injector (in the engine will do) so we can decide if its a standard design. if it is I am sure any diesel equipment specialist could supply the thinner copper washers.

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5 hours ago, Tony Brooks said:

Skimming a head with an absolutely flat mating face will not affect the compression or compression ratio, skimming the block will.

 

I still can't see the copper sealing washer thickness making a major difference but you said you have two 0.5mm washers. just heat these to cherry read and let them cool. that will soften them for reuse.

 

Is this a direct injection engine or indirect. If direct then it may smoke a bit under light loads, at idle and at low speed.

Sorry to contradict you but to anneal (soften) copper you quench after heating. 

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But maybe no of you are worried about scale as inside copper fuel pipes, but agreed in this case probably a better plan.

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35 minutes ago, Flyboy said:

Sorry to contradict you but to anneal (soften) copper you quench after heating. 

It doesn't matter. Copper which has been red hot will still be annealed, whether quenched or allowed to cool in its own good time.

Some copper alloys DO need to be quenched to soften them; conversely, some other alloys are hardened by quenchig

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1 hour ago, Iain_S said:

It doesn't matter. Copper which has been red hot will still be annealed, whether quenched or allowed to cool in its own good time.

Some copper alloys DO need to be quenched to soften them; conversely, some other alloys are hardened by quenchig

I beg to dissagree, allowing copper to cool slowly (tempering) it will revert to its original state.  If the science has changed in the last 50 years can send me a link with that information please?

 

Annealing copper makes it softer and less brittle, which allows you to bend it without breaking it. This malleability allows you to hammer and mold the copper into any shape you wish without cracking the metal. You can anneal any grade and thickness of copper as long as you have a flame that can transmit enough heat to the metal. The most straightforward way to anneal copper is by heating it with an oxygen acetylene torch and rapidly cooling it in water.

 
 

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Copper will remain soft if heated to just red and allowed to cool- Quickly or slowly.  

 

Tempering is when you heat something to a point below its annealing temperature and then cool it.  It is mainly steels that are tempered and the rate of cooling needed depends on what is in the steel, apart from iron and carbon.

 

Tempering has no effect on the sort of copper that washers and gaskets are made of.

 

Solution heat treatment followed by quenching is important for the age-hardening copper alloys ( typically those with aluminium).  These can be kept soft by keeping them cold ( think ice or dry ice)  after solution heat treatment. Any sort of rewarming makes them harden.

N

 

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With regard to incorrect size copper washers being installed into a direct injection engine. It does become a issue as it alters the position on the injector spray pattern.

Over the years I have been called out to lots of engines with reported smoke issues following injector replacement, most times this was due to people fitting copper washers into copper injector sleeves. By doing so the injector is lifted up from its correct position, thus altering the spray pattern. This in effect causing incorrect combustion due to incorrectly positioned spray. I have seen damaged injector sleeves due to the injector being so far back in the sleeve that the spray touches the  bottom edge of the sleeve. If left unchecked piston seizures is also a issue. 

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1 hour ago, Hot bulb said:

With regard to incorrect size copper washers being installed into a direct injection engine. It does become a issue as it alters the position on the injector spray pattern.

Over the years I have been called out to lots of engines with reported smoke issues following injector replacement, most times this was due to people fitting copper washers into copper injector sleeves. By doing so the injector is lifted up from its correct position, thus altering the spray pattern. This in effect causing incorrect combustion due to incorrectly positioned spray. I have seen damaged injector sleeves due to the injector being so far back in the sleeve that the spray touches the  bottom edge of the sleeve. If left unchecked piston seizures is also a issue. 

That may well be true but whether it does or not probably  depends upon the thickness of the land the nozzle sits against.

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The attached images show how Bosch supply injectors with a copper washers. When fitting into engines with copper injector sleeves the washer is clearly not required. However people with limited product knowledge often make the mistake of fitting supplied copper washers. As you can see in the attached images, it makes a considerable  difference to the position of the injector nozzle. This was the point that I was trying to make in my post.

 I have been remanufacturing Volvo engines for 39 years now, and this is not a uncommon occurrence when people change injectors.

1E364540-918C-4A96-A9F1-3A875FBD6931.jpeg

DDCF61E1-1335-4CE5-BC76-AAA43C4DA463.jpeg

4D9EFB67-7EE8-49C5-9D44-168FA03AF99B.jpeg

  • Greenie 1

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