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#45
by
Gizmoman
on 23 May, 2013 20:49
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For sure,
I believe it was my #3 GP that had the head missing entirely and bits of the rest were also gone. The tops of my pistons looked like gravel had spent some time there.
This all happened rather quickly on a return camping trip - probably the last 20 miles.
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#46
by
monomer
on 23 May, 2013 21:39
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Wouldn't a bad injector cause problems by erosion? Instead of finely atomized fuel combusting, a peeing injector could knock a glow plug tip off and wreck the cyl, or hammer the pre chamber with high pressure fuel.
It's got more then a messed up piston/head. The cylinder wall has all kinds of wear. Not consistent with chunks floating around.
I'm testing that injector to confirm the rest, as no-one has yet. it's all just blamed on a leaky injector. I need actual proof.
sidenote: where's everyone getting nozzles these days? all I see are prothe's and partsplace. Prothes will be cheaply made, and parts place is double what I paid for my last set. Brutal.
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#47
by
Gizmoman
on 23 May, 2013 22:12
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I now have eight.
4 originals and 4 brand new ones from Giles - you may want to try him for new ones as well.
It's been said in this post that diesel is a lubricant so having it leak wouldn't be a huge problem. I disagree if it goes on for a while. Calling diesel a lubricant is true when compared to gas, but compared to 15-50 wt oil, it's hardly a match - especially over 500 miles.
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#48
by
92EcoDiesel Jetta
on 24 May, 2013 04:24
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Wouldn't a bad injector cause problems by erosion? Instead of finely atomized fuel combusting, a peeing injector could knock a glow plug tip off and wreck the cyl, or hammer the pre chamber with high pressure fuel.
It's got more then a messed up piston/head. The cylinder wall has all kinds of wear. Not consistent with chunks floating around.
I'm testing that injector to confirm the rest, as no-one has yet. it's all just blamed on a leaky injector. I need actual proof.
High pressure water jet is used to cut stone . High pressure jet from a peeing injector is not a good thing.
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#49
by
TylerDurden
on 24 May, 2013 06:10
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Water jet cutting for metals includes abrasives.
AIUI, a pissing injector can create a couple of problems (at least): washing the cylinder & rings which adds wear; and detonation that hammers stuff apart because the "diffusion flame" doesn't form as the spray emits from the nozzle. Another paper I read indicated that late combustion burns the lubricating oil off the cylinder walls.
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#50
by
monomer
on 24 May, 2013 09:28
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What are the chances of just one injector acting up? The set came from the same place, and all have the same wear.
I think it's more than an injector.
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#51
by
wolf_walker
on 24 May, 2013 09:57
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After dicking around with a bunch of injectors, nozzles, and pop tester the last week or two, I'm more paranoid than ever
about the quality of rebuild jobs. Unless they are mass produced maybe the $45 an injector I see often listed by shops is not a lot of money for the
time involved in cleaning and pop pressure adjustment/matching/testing, and one usually gets what they pay for.
OP got his from Giles I think and I have no reason to think he does anything but
good work, and anything mechanical can fail.
I'm not in love with the spray pattern on any of the 8 new or 4 lowish mileage used Indian made Bosch nozzles
I've tested, which is what Bosch reman injectors use and have been using. No idea what Giles uses.
Anything can fail though even if it was right when they were built. And I have strong doubts that
the human eye can see anything beyond gross errors in spray pattern when testing injectors by hand.
I have two NOS German made OM617 Mercedes nozzles left still in the wax I might break out
and see how they spray just for comparison.
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#52
by
745 turbogreasel
on 24 May, 2013 12:02
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Water jet cutting for metals includes abrasives.
AIUI, a pissing injector can create a couple of problems (at least): washing the cylinder & rings which adds wear; and detonation that hammers stuff apart because the "diffusion flame" doesn't form as the spray emits from the nozzle. Another paper I read indicated that late combustion burns the lubricating oil off the cylinder walls.
I had one slice all they way into the water jacket of a fresh head in about a half hour of run time.
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#53
by
TylerDurden
on 24 May, 2013 12:26
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Impressive...
But considering VW's attitude* regarding spray, maybe only gross errors are significant.
*Somebody had a VW TSB saying that minor variations were not cause for repair/replacement.
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#54
by
wolf_walker
on 24 May, 2013 13:12
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Impressive...
But considering VW's attitude* regarding spray, maybe only gross errors are significant.
*Somebody had a VW TSB saying that minor variations were not cause for repair/replacement.
Bosch India sure took that to heart if so.
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#55
by
wolf_walker
on 24 May, 2013 13:40
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Impressive...
But considering VW's attitude* regarding spray, maybe only gross errors are significant.
*Somebody had a VW TSB saying that minor variations were not cause for repair/replacement.
Speaking of which, see last part of the second paragraph..
Course the MB prechamber design is pretty different than the VW one, but the injector and nozzle design is still
mostly the same. The MB prechamber is quite a bit further down from the injector and is a neat design if you've never seen one. (they also don't fall into the cylinder)
If anything I'd think spray pattern would be less critical for the VW design but what the hell do I know.
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#56
by
92EcoDiesel Jetta
on 24 May, 2013 14:52
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Mercedes idi pre chamber design is very different than VW's. Mercedes pre chamber has a red hot ball inside where the injected fuel stream strikes which further atomizes the fuel. Mercedes pre chamber is a "closed" capsule with 5 small holes (tiny compared to a glow plug tip) to let the flame out to the cylinder. A broken glow plug tip will stay in the pre chamber, unlike the VW, which will drop it smartly into the cylinder/ wreck your engine.
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#57
by
wolf_walker
on 24 May, 2013 14:58
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Mercedes idi pre chamber design is very different than VW's. Mercedes pre chamber has a red hot ball inside where the injected fuel stream strikes which further atomizes the fuel. Mercedes pre chamber is a "closed" capsule with 5 small holes (tiny compared to a glow plug tip) to let the flame out to the cylinder. A broken glow plug tip will stay in the pre chamber, unlike the VW, which will drop it smartly into the cylinder/ wreck your engine.
Yep. They generally last the life of the motor, call it half mil or so. Some guys drill the pre-chamber holes larger I've heard.
And that ball has been known to break off, but it stays put at least. Good design all in all.
I think the bit about tolerable spray pattern is interesting, and I suspect it came from Bosch rather than MB.
The VW has what, two inches from nozzle tip installed to the bottom of the pre-chamber? I would imagine that
spray pattern beyond two inches, for a VW, is irrelevant beyond it being an emphasized example of what's happening
within a few inches of the nozzle. Maybe. The MB guys don't want a mist, they want a coherent strong shot
down to that red hot ball you mentioned, at first thought it seems this might not be what one would want for the VW
swirl pre-chamber setup. Mostly thinking out loud here...
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#58
by
Gizmoman
on 24 May, 2013 16:07
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Mercedes idi pre chamber design is very different than VW's. Mercedes pre chamber has a red hot ball inside where the injected fuel stream strikes which further atomizes the fuel. Mercedes pre chamber is a "closed" capsule with 5 small holes (tiny compared to a glow plug tip) to let the flame out to the cylinder. A broken glow plug tip will stay in the pre chamber, unlike the VW, which will drop it smartly into the cylinder/ wreck your engine.
Yep. They generally last the life of the motor, call it half mil or so. Some guys drill the pre-chamber holes larger I've heard.
And that ball has been known to break off, but it stays put at least. Good design all in all.
I think the bit about tolerable spray pattern is interesting, and I suspect it came from Bosch rather than MB.
The VW has what, two inches from nozzle tip installed to the bottom of the pre-chamber? I would imagine that
spray pattern beyond two inches, for a VW, is irrelevant beyond it being an emphasized example of what's happening
within a few inches of the nozzle. Maybe. The MB guys don't want a mist, they want a coherent strong shot
down to that red hot ball you mentioned, at first thought it seems this might not be what one would want for the VW
swirl pre-chamber setup. Mostly thinking out loud here...
Interesting bit of info. I have four slightly cracked cups from the old head. Maybe I'll work out a way to spray the nozzle into a cup located similar to install. This would give a better visual for sure.
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#59
by
TylerDurden
on 24 May, 2013 18:36
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Quantum-Man scored a TSB binder and shared this on the other board... nobody there seemed to buy into the idea, either.
