Replacement injector tips - do you typically change them all?

scubaman

scubaman

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I've asked the local service engineer to pull out the injectors and have them tested, as the engines have done 800 hours and I thought it prudent to do so after all this talk of melted pistons, etc.

The engineer got back to me saying that replacement tips were required to all injectors (12 in all, á 100€).

I find it very hard to believe that all 12 were failing, especially as there were no obvious symptoms of failure. The soot was very reasonable, engines started well, ran smoothly as ever and gave me close to 32 knots.

I would have thought that only failing ones would be changed, but Is it typical to change them all while you're at it? I'm feeling dubious about this.
 
scubaman said:
I've asked the local service engineer to pull out the injectors and have them tested, as the engines have done 800 hours and I thought it prudent to do so after all this talk of melted pistons, etc.

The engineer got back to me saying that replacement tips were required to all injectors (12 in all, á 100€).

I find it very hard to believe that all 12 were failing, especially as there were no obvious symptoms of failure. The soot was very reasonable, engines started well, ran smoothly as ever and gave me close to 32 knots.

I would have thought that only failing ones would be changed, but Is it typical to change them all while you're at it? I'm feeling dubious about this.
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When I pulled them way back you will know when they were cleaned and pressures set , the only comfort you can gain is that you will have a 1000 hours run time before you need look again , price isn’t bad either as long as there genuine Bosch and the Chinese Shyte hasn’t crept into your supply chain like it had this end of Europe . Sorry I mean good old British England .
 
scubaman said:
I would have thought that only failing ones would be changed, but Is it typical to change them all while you're at it?
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Afaik it is, at least for some other engines that I know better than yours (Cat & MAN).
Otoh, there's also a school of thought according to which, as long as you keep a close eye on any possible sudden excess of dark smoke, the old rule "if it ain't broke, don't fix it" is valid also for injectors and their nozzles...
In fact, I'm aware of a couple of boats with MAN old(ish) mechanical engines which exceeded 3k hours without ever pulling the injectors.
Though both are actually commercial boats, and according to all the engineers I came across, that does make a difference, because engines regularly used through the year are known to reach hours counts which are unheard of, in pleasure boats.
 
I just posted a comment in another thread related to how to check (albeit empirically) if each injector is working as it should without pulling them out.
Not sure about how feasible/easy it can be in VP engines, but fwiw you can see here how to do that on MAN V engines.
Just in case anyone reading this thread and not the other one might be interested... :)
 
volvopaul said:
When I pulled them way back you will know when they were cleaned and pressures set , the only comfort you can gain is that you will have a 1000 hours run time before you need look again , price isn’t bad either as long as there genuine Bosch and the Chinese Shyte hasn’t crept into your supply chain like it had this end of Europe . Sorry I mean good old British England .
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Thanks Paul, I did remember that you had them checked, but thought it might be a good time to do it again to be on the safe side. I was expecting a similar outcome now and was a bit surprised to have all of them changed... Well, should be good for many years to come as you say. Trouble is that I have no way of knowing where the nozzles came from.

I'm going to give the diesel shop a call to learn more.
 
Thank you everyone for your replies. It seems that changing them all is more or less business as usual.


MapisM said:
I just posted a comment in another thread related to how to check (albeit empirically) if each injector is working as it should without pulling them out.
Not sure about how feasible/easy it can be in VP engines, but fwiw you can see here how to do that on MAN V engines.
Just in case anyone reading this thread and not the other one might be interested... :)
Click to expand...

Thank you, P, for the link.

If i've understood correctly, one of the ways an injector nozzle can give problems is when it starts to spit out droplets (instead of properly atomised mist, so to say). These droplets when combusted on the piston surface can lead to all sorts of problems.

But in essence, the amount of fuel given out by the injector pump would be the same, it's just that all the energy (and heat) is concentrated on a very small area.

On the whole, the amount of fuel burned, and the temp of the exhaust gas would be pretty much the same, and something that would be very difficult the tell by measuring the end of the bolt, as per your post on the other thread?

Wouldn't this apply to even a totally failed, 'hosing', nozzle in an mechanical engine?

Hope my explanation makes any sense.
 
fwiw,
some years ago we changed all nozles on our 2 x MAN's that was after 900hrs
2y ago, we changed all nozzles on both our genny's, afaik they were never changed during >3500hrs

in each occasion there was a well noticeable improvement on less smelly (grey blue) smoke
my feeling is that the injectors (and or the nozzles) suffer a lot,
so for piece of mind when you consider replacing just do them all
 
Mine d12 715 hp are in the shop at present and have all just failed a bip test

They believe that by taking to bits , cleaning etc they maybe ok. Apparently there are currently no parts available to rebuild them which for a2004 d12 I find strange. I hear back later / tomorrow.
 
scubaman said:
If i've understood correctly, one of the ways an injector nozzle can give problems is when it starts to spit out droplets (instead of properly atomised mist, so to say). These droplets when combusted on the piston surface can lead to all sorts of problems.

But in essence, the amount of fuel given out by the injector pump would be the same, it's just that all the energy (and heat) is concentrated on a very small area.

On the whole, the amount of fuel burned, and the temp of the exhaust gas would be pretty much the same, and something that would be very difficult the tell by measuring the end of the bolt, as per your post on the other thread?

Wouldn't this apply to even a totally failed, 'hosing', nozzle in an mechanical engine?

Hope my explanation makes any sense.
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Yup K, I fully understand your explanation, and I can see why what you are suggesting could indeed happen.
Otoh, behind the few horror stories I heard about holed pistons/wrecked engines, allegedly there was always a fault well beyond a sub-optimized spray pattern, i.e. an injector(s) stuck open and/or very corroded nozzle(s) - or problems with valves, but that's another chapter.
As I understand, the most typical symptoms in these situation are both darker smoke and higher EGT (also at lowish rpm), well before the engine goes belly up - though of course the sooner you turn it off, the better.
Now, keeping an eye on the smoke is obviously much easier than spotting higher EGTs on mechanical engines without such gauges, but that's already much better than nothing.
You wouldn't believe how many fellow boaters I've had onboard who were surprised to see that I had the habit of regularly giving a look astern while cruising... :ambivalence:
 
jrudge said:
Mine d12 715 hp are in the shop at present and have all just failed a bip test

They believe that by taking to bits , cleaning etc they maybe ok. Apparently there are currently no parts available to rebuild them which for a2004 d12 I find strange. I hear back later / tomorrow.
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Urgh, that sounds worrying.
I didn't remember that you had to pull out the engines btw, weren't they on rather low hours and running fine upon purchase? And if so, what happened later?
All the very best anyway!
 
jrudge said:
Mine d12 715 hp are in the shop at present and have all just failed a bip test

They believe that by taking to bits , cleaning etc they maybe ok. Apparently there are currently no parts available to rebuild them which for a2004 d12 I find strange. I hear back later / tomorrow.
Click to expand...

There are 2 different manufacturers of the D12 injector and it so7nds like you have the unpopular ones .
 
petem said:
I believe he's talking about the injectors, not the engines!
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Doh! Did you already know that?
I'm asking because if it was obvious from jrudge statement, my understanding of EN must be getting worse... :ambivalence:
 
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