Never assume anything...

I recently diagnosed my hard-to-start problem as a loss of pressure (fuel bleed down) in the injector lines. Since my injectors are less than three months old, I assumed that the problem was elsewhere. I subsequently replaced the brass o-rings underneath the delivery valves in the injection pump to eliminate potential leakage at that source. The engine idles _ever_so_slightly_ better, so apparently there was some leakage in one or more of the o-ring seals, yet the starting problem was not resolved.

When I pulled the injectors out to check the engine compression, it turns out that two of the injectors leaked so badly that I could see that the ball pins in the pre-chambers were wet with fuel. One of the other injectors has a small amount of external seepage as well. This points to some serious quality control issues. Three injectors out of five are bad – that’s ridiculous. I'm curious what other people's experiences have been with genuine Bosch brand rebuilt injectors.

I would like to know if anyone else has experienced these quality control problems, or conversely, please chime in if you have had success in using them. I'd like to get a feel for whether this was just an isolated case of someone having a bad day at the factory or if there is a consistent problem. I'm a little gunshy at this point about having blind faith and just installing a new set of injectors. If it turns out the other people have had these problems, I'll obtain the new set under warranty and send them to a diesel service shop to have them pressure checked before installing them -- however I don't want to go through this extra expense if it's unnecessary.

I appreciate anyone's replies to this inquiry. Thanks in advance!

RTH

I've found the Bosch/MB rebuilt injectors to be consistently poor in quality. Definitely have them tested and/or rebuild by a competent diesel shop.

__________________
Regards,
Aaron

The only failures that WE have seen with Bosch rebuilt are when the fuel system is contaminated already! Bosch uses new "tips" the actual nozzle on all of the rebuilds.
IN the 80's when MB was selling over 60% diesel cars we were allowed to rebuild these nozzles under warranty, & they didn't last 20,000 miles.
MOST of these problems are due to POOR quality fuel!! over; dirt & water.
On many cars we had to install water separators in the fuel system so that the injectors would last at least 50,000mi.
ASK yourself WHY did the first injectors fail causing you to replace them in the first place???
Have seen many diesel motors with 300,000 and original INJECTORS!

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MERCEDES Benz Master Guild Technician (6 TIMES)
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MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
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Retired Moderator

Thanks guys -- I really appreciate your help!

M.B.Doc: The fact that Bosch uses new tips is the reason why I decided to go with them rather than having the originals rebuilt by a diesel service shop. The injectors were replaced when I bought the car at just under 200,000 miles; not for any particular reason other than overzealously thinking it would be a good idea just keep the engine happy (I need to practice the mantra "if it ain't broke don't fix it"). The fuel system is not contaminated with water nor algae, I have been using RedLine DFC or 85+ religiously, & Power Services additive occasionally; the filters have been changed twice - once when I bought the car & again 3000 miles later (again, for no particular reason other than being overly zealous & thinkg that perhaps the additives may have disloged some crud in the system). The car now has 204,000 miles on it.

Two questions:

1. Were the injectors that you were rebuilding failing at 20,000 miles due to re-grinding the tips vs. replacing them?

2. Do you know if all Bosch injectors are rebuilt at the same facility, or at different locations, which could account for discrepancies in quality control?

Looking forward to your reply... Thanks again!

RTH

Thanks for the information everyone. I guess that I’ll get the 5 injectors due to me under warranty, plus I’ll buy five more, then take them all down to get tested. Hopefully, I can get a 50% success rate (?!) and return the other ones. I hate to do that to the supplier, but if they are providing defective parts, I guess I shouldn’t feel too guilty about returning the others.

RHT

Back in the 1980's MB didn't offer reman nozzles & fuel quality was very poor. ALL of the injectors that we rebuilt got new tips but with the fuel problems they would fail! For example the 1982 cars had a 2yr 24,000mi warranty & most needed injectors durning the warranty period!
EVERY time you buy fuel there is a chance of water being in the fuel. Water in the fuel causes heat & that will cause the injector tips to seize. That is why most trucks & heavy equiptment STILL have water seperators!

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

M.B. Doc:

You have me convinced. Even though I obtain fuel from high turnover stations to avoid contamination, that won’t address water accumulation due to condensation within the tank. I just picked up a Racor fuel/water separator. I have 10 new/rebuilt Bosch injectors in my trunk, so I’ll be getting them tested (hopefully soon) before installing 5 good ones from this batch.

Thanks for your help!

RTH

What is the approximate difference in price between a new and rebuilt injector?

I took 10 fresh rebuilt Botch injectors to a very reputable diesel injection shop today. None of them leaked, and every one of them was actually within specification as far as opening pressure is concerned, with some variability. So technically speaking all of them would pass a rudimentary examination.

However there was definitely a difference between them regarding the spray pattern, a difference that was clearly visible even to my untrained eye. Plus the technician pointed out how some of them had a certain amount of "delay", plus some of them had a better "chatter" to them. He explained how the lesser ones would be fine, but would most likely not last as long as the better ones. This is from a guy that does nothing but rebuild diesel injectors all day long for living. I found this to be quite interesting.

In conclusion, it seems that the batch that I first received are not necessarily indicative of all Bosch rebuilds being garbage. They generally seem to be adequate, yet not excellent. Perhaps my first batch was the product of some unusual screwup at the rebuild facility -- frustrating nonetheless.

Needless to say I'll be installing the five best ones tomorrow.

RTH

PS: PaulC: I'm not even sure if NEW injectors are available.