I recently purchased a low mileage (86K miles) 300D it was a really nice original one owner car. It started and ran great, smooth and had good power. I decided to just do a major service on the car because of its age this included checking the injectors. The injectors still had the original Bosch German-made nozzles. 3 of the injectors were peeing (squirting) fuel before they released and sprayed, 1 of the injectors was peeing all the time (leaking) and 1 injector was spraying off to the side.

I could not tell by the way the engine started or was running that I had bad injectors, I had to test them to find out. Even tho the engine ran great bad spray patterns can cause other problems long term.

I have limited experience with injectors, I've only had a couple of sets apart. There are people on this forum that have rebuilt hundreds of sets, talk to them for recommendations. Or buy rebuilds for someone you trust, buying off the shelf is a roll of the dice IMO.

I don't know this from experience but from reading this forum the made in India Bosch nozzles do not have the best rep.

If you buy rebuilt Injectors from a normal auto parts they are going to have the Indian Bosch Nozzles in them and the chances of the being balanced is not as good.

When a shop or someone like grezzaer (spelling" forum member that rebuilds injectors) rebuilds the Injectors they balance them closer than what the manual has as acceptable.

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84 300D, 82 Volvo 244Gl Diesel

Greazzer just rebuilt my W115 injectors with Monark nozzles. I'd like to try Bosios in my W123 (which I will also be sending over to him next year). Just need to find a full set.

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Why I will never do business with "DieselKraut" again

http://www.peachparts.com/shopforum/mercedes-benz-used-parts-sale-wanted/378935-why-i-will-never-do-business-dieselkraut-again.html

I just rebuilt mine with Firad nozzles. I have one nailing that follows the nozzle if swap cylinders. I disassembled it and it has light scoring in one area and doesn't seat well after popping. I also have one leaking at the half despite lapping it to a mirror finish with 2000 grit.

The bosch nozzles do pee if the pressure is applied too slowly. I think this is a "feature" of the drilled pintile.

Had same problem leaking at half,Problem was carbon build up on ledge on lower half
of housing,not well seen. Small sharp edged screwdriver took care of problem.
Because the injector tip does not set square in housing can cause leak and poor spray.

Bosch are probably made in China these days and they have at least a 20% fail rate right out of the tube. The older ones were/are made in India and prior to that France. Chinese made nozzles are poor. Any person can buy them off Alibaba.com for around .52 cents a pop. I tried a lot of 100 a few years ago. Over a year of tinkering with them and all but a few out of that 100 failed entirely. Anyone who thinks it’s just a matter of just calling the parts store to exercise some sort of 24-month warranty has a lot of extra time on their hands. Right now Monark was /is the only German maker of nozzles. They took out DES circa 2014 from memory. You can still find DES branded nozzles floating around. Most of the German lathes have been shipped off to Eastern Europe or beyond. Italy’s Bosio are headed the same way. Closing in on my 1,000th set of injectors here shortly and I’ve concluded the global powers will choke these old oil burners out of existence in the years to come by getting rid of simple items like nozzles. I tried unsuccessful for over a solid year to find any USA manufacturer to make me some nozzles. I provided the specs and drawings. Even offered $100 a piece and not one USA firm could lift a finger. I tried India mart and going through Alibaba.com and tons of interest but zero follow through

German made or Italian made is the last refuge of some notion of quality.

I have located Delphi brand replacement injectors for the 617 mercedes diesel engine for around $95/each. I can't imagine a company like Delphi putting their brand name on junk.

$500+ plus sounds like a bargain to me. I’m sure the average W123 owner thinks the same way too.

Monark is no longer interested in supporting Classic Mercedes diesels. They've stopped supplying items like nozzles and oil cooler hoses already.

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Why I will never do business with "DieselKraut" again

http://www.peachparts.com/shopforum/mercedes-benz-used-parts-sale-wanted/378935-why-i-will-never-do-business-dieselkraut-again.html

I'm finding pricing on any and all parts for these W123s is going up. And we should all take note that these were never built as a "cheap car". MB never used the word "cheap" in their advertising.

If you are going to drive and operate the best, get ready to pay the freight. Either that or go buy a Ford.

In old threads back in 2007-2008 I said where I worked we used 500 grit lapping compound. No one was interested and said it had to be a finer grit then that and I never argued the point. But I worked for 5 years in a fuel injection shop and in that time I must have done 100s of injectors during one year. Again we use 500 grit lapping compound but we had a real lapping plate.

When I no longer worked for the fuel injection shop and had to lap the parts inside of a Caterpillar Fuel Injection Pump at work I used Comet Cleanser and a piece of flat window glass. It worked fine.

When I rebuilt the Injectors on my Volvo Diesel and Mercedes I used a flat piece of glass again but bought 600 grit lapping compound from an eBay seller that sold stuff for polishing Rocks (I believe it was aluminum oxide) and that worked fine. It leaves that lapped area a light gray color and you can see any area that did not get lapped as it will not be that gray color.

Later I got a good deal on a lapping plate but have not used it for Injectors.

So you have nothing to loose by lapping the leaker with typical house hold Cleanser (bonamie is not gritty enough) like Comet or Ajax.

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84 300D, 82 Volvo 244Gl Diesel

So, are both Bosio and Monark injectors not available for sale in the United States?

I see them on eBay pretty frequently (the Monark's at least). Doesn't seem to be any off-the-shelf suppliers here stateside unfortunately. I've got Bosch India injectors in my car right now (installed maybe a month or two ago) and so far it seems OK but cold start is still a little *meh*. I plan to rebuild my Bosch Germany ones that came out with some nice nozzles once I decide which route to go (looking like Monark or Bosch are only options for me where currently located)

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{2010 Mazda 3 266,000mi} - daily since new, Airlift suspension + some chunky sway-bars: fastest pass 17.7@77MPH
{1987 300SDL 256,000mi} - stock turbo @ 22lbs straight piped + a whole bunch of pre-turbo water/meth injection, 722.3 with increased line pressure, special sauce, and shift kit: fastest pass 16.5@82
{1992 964 Carrera 4 Frankenstein ??,???mi} - 993 forward dated, Speedster conversion, GT45 + E85: fastest pass 12.5@113

A year-and-a-half ago when I got my 83 300CD I could not find any Monark or Bosio nozzles for sale, so I got brand new Bosch India complete injectors and put them in. I did not test for pressure or spray. A few months later I got Bosio nozzles and had Greazzer do up the original injectors proper.
Changing from brand new Bosch India nozzles that were few months old to Greazzer's was a remarkable difference. Ar idle they were smooth and quiet in comparison. It was a completely different engine. When good nozzles dry up shortly the 617 is doomed. It will run, but not as it should.

I just got a set of Indian Bosch reman injectors thinking the Firad nozzles were a problem. I bought 6 thinking that one would likely fail pop test. Pressures were 1750/1750/1800/1800/1875/1700 so not balanced by any means. The last 1700 one I couldn't make "pop" using the hand knob on the tester, no matter how quick I made half turns. It also peed at a much higher pump rate so that one is going back. The 1875 nozzle probably should have been re-shimmed, but I didn't want to take it apart yet. It had a nice high pitched sqeak, and popped very cleanly even with the hand knob. The machined surface on the bottom of the Bosch nozzles was terrible. Perhaps to save money they skimp on surface finish since that surface is not functional.

The Bosch smoke more than the Firads, for sure. Idle is the same. No leaks, but also #1 cylinder is still not happy. Compression was good on it a few months ago when I tested it, but it is definitely the noisy one at idle. When the engine is off idle, it quiets down. Gets better as it warms up, but still there a bit. Perhaps the pump needs calibrated, as it may have 363k on it.

In summary, my issues are likely not due to the Firads, and seem to be more repeatable on the tester than the Indian Bosch. I'll keep them as a backup set.