Anybody tried bringing old junk nozzles back to life using grinding paste? I have these old injectors that came with my #17 head which installed 3 years ago. The injectors were caked in waste vegetable oil goo. Nozzles were seized solid so I dumped the whole lot in a jar full of acetone and forgot about them for the last few years. Fast forward to today and some of them actually came apart. Disassembled everything threw them in a tumbler for a few minutes with fresh acetone. But of course the pintles got separated from their nozzles. When I tried one and the pop tester it was just pissing all over the place starting at 400psi. So I used a bit of metal grinding paste on the tip of the pintle and a drill like this:
https://youtu.be/W-bazrdH1HM
FF to 6:20

And the result...
https://youtube.com/shorts/WRqYJelHkZg?feature=share

The pop pressure is a bit high but no pissing, leaking dribbling etc. This is a bosch india 265 nozzle. Not exactly known for its high quality. I'm tempted to try these in the car just for shlts and giggles. Bad idea or terrible idea?


https://imgur.com/a/C5Xwwsx

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CENSORED due to not family friendly words

I have done similar with valve lap compond but by hand. It has always improved the spray pattern. I would instal them after a cleaning everything up again.

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92 e300d2.5t
01 e320
05 cdi
85 chev c10

By doing that, you have destroyed the nozzles. They are machined to less than 0.000xx" tolerances. Adding a ten-thousandth to that by wearing them with that paste they are junk.
Pintles and holders are matched sets, if they are separated and lost track of their match they are worthless.

Yeah, I'm not so sure about that. These were garbage nozzles ready for the bin, why not experiment on them? They're working a lot better now than when I got them.

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CENSORED due to not family friendly words

These days, unless you are stepping up to more expensive nozzles, those super-tight precision and matched tolerances of (made-in-x) bosch nozzles are a crap shoot with a high leak rate NEW. It's like they don't care anymore and expect people to fix them.

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1985 300TD 1981 Scirocco 1.6D conv 1986 Golf 1.6D 2003 Golf TDI

You truly think one can remove 10 mil w/ a little paste. Maybe if you spun it for a year. For reference, the spark plug gap in an old 1960's engine is 35 mil. The pop-tests looked good, so what is the risk? Just need to swap in a thinner washer on the spring or sand down the existing one. To adjust the other way, I bought a few bags of thin washers from McMaster-Carr (posted PN's in past).

Re pop-pressure, I suspect people exaggerate the importance. I say this because as-found my 1985 300D had 3 non-turbo injectors installed, which popped at 1500 psig (recall). Replacing them and adjusting all to the correct 1950 psig didn't noticeably affect how the engine runs. My home-made pop-tester has both a mechanical gage and an electronic pressure transducer so I can electronically record the pressure trace and better pick the peak where the poppet first opens, but really over-kill re above experience.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans

Correct me if I’m wrong, but I believe the number to the left of the decimal is one mm -unless there’s a reason people need to measure tolerances in meters. Think he’s talking about removing one ten thousandths of a mm.

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1981 240D 4sp manual. Ivory White.

Sorry, I was thinking like a 'merican. Probably did mean mm. If true, then 1/1000 of a mm is 1 um (micrometer or "micron"), which is slightly more than a wavelength of visible light (400 to 700 nm). That level of material removal is termed "polishing" since the surface can then reflect light without much scattering. I think that polishing is what the OP intended to achieve and don't see how it could make an injector pintle worthless.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans

Points and plugs gaps were in inches. I set plugs at 32 (probably thousants) and don't remember point gap, 28 maybe. Seem like I bought a dwell meter when I got the dual point distributor.

"...never remember..." What a redneck!

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84 300SD
85 380SE
83 528e
95 318ic

This is an interesting thread. All my old nozzles are in a box. I’m going to be keeping them after reading this. Never know…the way my cars keep going I’m going to look and nozzles may be NLA at some point.

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79 300TD “Old Smokey” AKA “The Mistake” (SOLD)
82 240D stick shift 335k miles (SOLD)
82 300SD 300k miles
85 300D Turbodiesel 170k miles
97 C280 147k miles

"A mil is a thousandth of an inch — .001 inch. It is a typical manufacturing dimension."

https://www.deeproot.com/blog/blog-entries/mil-thickness-what-does-it-mean-and-how-do-i-measure-it

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“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now

Correct. Injection parts are matched to the 0.000x inch tolerance, modern ones can be even tighter.

Well now they're matched even closer.

.00000000000000000000x inch tolerance

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CENSORED due to not family friendly words

So you meant the OP might have removed 0.1 mil (0.0001") with grinding paste. When you said "10 thousandth", I interpreted as 10 x 1/1000 of an inch, or 10 mil. What you meant was "one ten-thousandth".

That seems reasonable since grinding paste is a bit coarser than polishing compound, which removes on the order of 0.5 micron = 0.02 mil. 2000 grit sandpaper is in that ballpark since it can polish a metal surface mirror smooth. But, I doubt it would be a problem. The main criteria in the pintle surface is that it be very conical to give a tight seal and uniform opening around the circumference as it opens. If one removes enough metal that the pintle sits lower in the hole, that will just result in a lower pop pressure, which can be adjusted by adding thin washers behind the spring. As long as he spun the pintle in the paste, it should be uniform.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans

I think this is a good idea and thread .

Ignore those who don't understand the way it works, either you get a proper spray pattern and pop pressure or not .

The you tube video clearly shows an off set spray cone and the higher pop point is a serious thing .

I'd suggest trying again and see what you get, once the pop pressures are close you'll be amazed at how much smoother the engine runs and smokes less too (it shouldn't smoke at all) .

My first OM617 was a 1979 300CD, no turbo and the injectors were all over the map, a nice guy who's long gone took them and cleaned the clogged nozzles with dental root canal tools ( !?!?) so they sprayed like tiny fire hoses but all at the same pressure and interestingly enough the car never smoked and ran smooth as silk and not as slowly as other NA OM617's Ive ridden in either...

I couldn't stop thinking about the improper spray pattern (you need a perfectly conical fog of fuel at the *precise* pop pressure) so as soon as I could I bought a set of rebuilt injectors but I did run the car that way for months, commuting and road rallying with now complaints .

Lapping precision parts is a long forgotten process because it takes time and effort but I think this is worthwhile .

I have some used, not junk injectors if you'd like to try again, next time keep the pintles and nozzles matched and only clean the rest in bulk batches .

Harbor Fright Tools sells nifty ultrasonic cleaners that work very well indeed, maybe try one here ? .

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-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better