Had my injectors tested. Need input. - Page 4 - PeachParts Mercedes-Benz Forum

TomJ · #46 07-07-2004, 11:00 AM

Quote:

Originally posted by DieselAddict
I tested my old German nozzles tonight and it appears that 4 of them have good spray pattern and 2 have decent pattern. Of the new Turkish nozzles, 4 had good pattern, 1 had decent pattern and 1 had bad pattern, almost a solid stream. So it looks like my 18 year old German nozzles are better than the brand new Turkish ones. Now I just have to decide if I should return all the new nozzles or keep 2 of the good ones to replace the German ones with the "decent" pattern. Any thoughts?

The way I judge the pattern is by looking at the width of the cone. The "decent" ones had a somewhat narrower cone than the "good" ones, but no solid stream like the "bad" one. Is it correct to assume that the wider the cone the better the spray pattern or is there a point of no returns?

Interestingly, the pop pressure does vary with different nozzles. I tested all the old German ones in the same injector and got a variation of up to 14 bar.

The turk nozzles are likely better than the India ones. One out of about 10 of the India ones are good (though one out of the four that Kamil sent me was good, so that lowers the ratio I suppose.)

What you are looking for is a good cone and fine spray, but also a "clean" pop, not a "long" pop or squirting and no “after squirt”, just a quick on/off. It should have a certain sound to it, hard to describe. The older German nozzles probably "pop" and spray correctly. Most of the ones that I have with worn in nozzle bases (in the area not covered by the heat shield) still pop and spray really nicely.

Anyway, was finally able to take pics of the various nozzles.

Here's an older German one with about 225k miles on it (notice the finely polished actuation angle on the pintle):

Here's a newer style German nozzle (etched, not machined lettering):

Here's a new French made nozzle:

And here's an India made nozzle with about 200miles on it (never sprayed right, removed and re-installed old German nozzles):

Notice on all but the older German one that the actuation surface is roughly machined and there is a step from it to the vertical surface of the tip. Not sure if that is telling, but I do know that when I used polishing compound on that surface of an India made test nozzle, the spray was finer and more consistent, though I wouldn’t suggest doing this on your own injectors, just wanted to see what effect it would have.

kmaysob · #47 07-07-2004, 04:02 PM

how hard is a pop tester to use?

DieselAddict · #48 07-07-2004, 08:59 PM

It seems like everything about Mercedes was better in the old days, especially the injectors. I returned all the Turkish nozzles today and I'll try to balance my injectors with the old German nozzles. First I'll do a lot of part swapping, and if that doesn't work I'll try to get some shims. Too bad there isn't some mechanism for easily setting the pop pressure, like setting the gap on spark plugs. That'd be nice.

kmaysob, using a pop tester is easy. The harder part is removing and disassembing the injectors as you have to work carefully and make sure everything is clean.

Sooty Taillight · #49 07-07-2004, 09:03 PM

DieselAddict:

Is you pop tester commercial or homemade?

phantoms · #50 07-07-2004, 09:12 PM

I searched here (fastlane), and see that they list 1.85mm for 33¢ each. They also list 1.60mm shims, but have a note that they are no longer available.

DieselAddict · #51 07-08-2004, 12:53 PM

The foolish me was too hasty with the return of the new nozzles. Late last night I found out two of my German nozzles squirt if the pressure builds up slowly. Thanks Tom for pointing out this test to me. So I had to order 2 nozzles again. I was so worried that my 30-day refund period would expire so I rushed to return those Turkish nozzles, believing all my German ones were fine, but that was before I knew about the squirt test. The good news is that I was able to balance the rest of my injectors to within 2 bar after some lengthy part swapping.

Sooty Taillight, take a look at the injector tester link at the beginning of this thread. That's the one I bought.

DieselAddict · #52 07-10-2004, 12:07 AM

I got those two nozzles today and this time they're the India ones. Tonight I tested them and of course they're both crap. Both squirt, and one squirts so bad it could be used to administer vaccines. Damn it I should've kept the Turkish ones, though I have no idea whether they would have squirted too as I didn't test them for that. Tomorrow I'll do some hunting at the local part stores like Napa and Pep Boys. I can't believe all these online stores sell crap like this. We should boycott this crap or something.

DieselAddict · #53 07-11-2004, 03:39 AM

None of the local stores had anything so I went to the local Pick-n-Pull and pulled 3 injectors out of a W116 turbodiesel. I know, different model, but I figured maybe the nozzles are compatible. They all turned out to be bad anyway, even though some were clearly not original because they were French. So the bad news is that I wasted more money, though I did purchase the exchange policy so maybe I can find something else more useful in the next 30 days. The good news is that tonight I aggressively cleaned the two German nozzles that were giving me problems and now they no longer squirt! So actually I will now be able to reuse all my original nozzles. Next I'll do this same thorough cleaning on the rest of the injectors, retest them and finally install them. After having my 87 300D on the operating table for over a month, I can't wait to drive it again.

FrankM · #54 07-11-2004, 05:47 AM

Quote:

Originally posted by DieselAddict
. The good news is that tonight I aggressively cleaned the two German nozzles that were giving me problems and now they no longer squirt! So actually I will now be able to reuse all my original nozzles.

can you describe how you "aggressively cleaned " the injectors?

this may be good for all of us

DieselAddict · #55 07-11-2004, 02:00 PM

Basically in addition to spraying all the injector parts with Super Lubricant (for those who don't know you can get this at Pep Boys) I took each nozzle, removed the pintle and then wiped the outer bottom of the nozzle and the tip of the pintle with a soaked paper towel until I was no longer getting any carbon on it, then sprayed it some more to get rid off any lint. You can really get a lot of carbon off the nozzles this way (something that Diesel Purge won't do sufficiently) and it does make a big difference in the nozzle's performance. I suppose you could do this without disassembling the injector, but the tip of the pintle will be in the way and you may not be able to clean it completely. I needed to disassemble the injectors anyway for balancing.

coachgeo · #56 07-11-2004, 02:12 PM

What would be interesting IMHO is to "aggressively" clean a new Indian injector that sprays bad and see what happens. Wonder if they are not using a clean room when putting the injectors together. I know the machining did not look to good compared to the German but...

coachgeo · #57 07-11-2004, 02:19 PM

Quote:

Originally posted by TomJ
...when I used polishing compound on that surface of an India made test nozzle, the spray was finer and more consistent, though I wouldn’t suggest doing this on your own injectors, just wanted to see what effect it would have.

Why do you suggest against this? Could it change volume or some other characteristic of spray that much for the worse?

What surfaces on the nozzle are critical to volume, timing of spray, spray pattern etc., and what surfaces are critical in sealing when closed? Just curiouse.

rwthomas1 · #58 07-11-2004, 09:57 PM

I am wondering if the pintle and nozzles of old injectors and the new Indian ones can be cleaned up with some aggressive polishing with Scotchbrite pads? Maybe chuck up the parts in a lathe or drill press and spin then against the Scotchbrite? If you could smooth out the rough surfaces they might perform okay... RT

rwthomas1 · #59 07-11-2004, 09:57 PM

I am wondering if the pintle and nozzles of old injectors and the new Indian ones can be cleaned up with some aggressive polishing with Scotchbrite pads? Maybe chuck up the parts in a lathe or drill press and spin then against the Scotchbrite? If you could smooth out the rough surfaces they might perform okay... RT

DieselAddict · #60 07-12-2004, 02:06 AM

It's definitely the loose tolerance and inadequate machining that's causing the Indian nozzles to perform poorly, not dirt. There's no reason to do "aggressive cleaning" on these nozzles because there's no carbon on them, just some lint which I sprayed off anyway and it didn't help.

Hopefully I'll install those injectors sometime this week. I'm curious whether I'll notice any difference in engine sound or performance after all this cleaning and balancing.