K-Jet Injector problems

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Styria

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As you guys would be aware, I am carrying out a valve grind and de-coke on my Astral Silver 6.9. Prior to dismantling, the car was not exactly a sparkling performer in the acceleration stakes, but a lovely and effortless cruiser on the freeways.

As part of the work, and prior to re-installlation in the inlet manifold, I was able to get the injectors tested. To say that the result of the testing was a disappointment, is putting it mildly. Out of the eight, from memory only one was holding pressure properly and providing a satisfactory spray pattern. The other seven, in one form or another, are in some way faulty - to the degree that one would waste their time refitting them to the engine. Really, it is a surprise that the car ran at all.

Therefore, what is one to do ? Clean them and, if so, how ? Somewhere I have seen one of S-Class' pictures of ultrasonic cleaned injectors. They looked like new, but did they work after cleaning and what were they like prior to cleaning. As it stands, the internals of the injectors have a tiny coneshaped filter, and a spring loaded metal valve retained by a collet similar to a normal valve. My contact that tested the injectors maintains that they cannot really be cleaned as there is no way of cleaning the filter and no way of blowing back any dirt particles on account of the spring loaded valve. Anyone have any thoughts on this ?

What I found also was as follows - and it relates to storage of spare injectors. In my opinion, they need to be stored in some sort of lubricant to stop the internals from drying out. I had quite a lot of 'dry-stored' injectors, mainly the brass type, but only three out of about twelve passed the pressure and spray test. Some of them didn't work at all. Tapping them sometimes made a difference, but not good enough to refit them with peace of mind. I also had about twelve steel type injectors that had been sitting in a petrol/oil filled container, and all bar one tested well enough to be re-used. Thus, I am really looking forward to how the silver car performs once the job is completed. There should be a considerable improvement. Regards Styria
 
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Fotografa

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Ultrasonic cleaning can work wonders, but ensure you use a heated cleaning unit, and best to clean them in injector cleaning solution in the unit. However, because K-Jet injectors are so damn cheap, ultrasonic cleaning is normally reserved for the more expensive D-Jet injectors, and K-Jet's are mor likely to just be replaced.
 
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Styria

Styria

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Hi Fotografa, thanks for your advice. Naturally, I have to ask you two questions, viz.

1) Have you had any K-Jets ultrasonically cleaned and also put them to the test ?

2) If you have, who in Sydney carries out this work and do you have any estimate or even exact price per injector?

There may perhaps be another way of cleaning them, but it'd be a matter of trial and test and that would be to soak them in thinners, and tap any debris back out the injector. It might work. Other than that, as you say, new is the way to go. BTW, I have also been told (some 5-6 years ago by Mercedes Benz specialists) that new 'after-market' injectors are 'crap'. Furthermore, one of the Club members was advised, again by a Benz specialist, that all new K-Jet injectors must have a (whatever) solution pumped through them to clean them out and test the spray pattern. You may wish to comment on those 'bush tales' (?). Regards Styria
 

Fotografa

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I'm not sure about 'aftermarket' K-Jet injectors, as I have only ever seen Bosch ones, which are the OEM items. The bosch ones are so well priced that even if I cam across some other brand aftermarket ones, ther would be no financial advantage in taking the risk to to go with unknown brand.

Of all the Merc's I've owned, only one was K-jet, and I never did any work on it, but if I did ever have injector issues with a K-jet, I'd just replace them, again, do to the low cost of replacement.

With a D-Jet, when you are cleaning refurbishing it, the are run through 3 ultrasonic baths, firstly you do the bottom of the injectors, then you do them whilst pulsing the injectors on and off, then one last clean in fresh solution, again whilst pulsing on and off.

Then they are usually back flushed at high pressure to remove any particles.

Also prior to cleaning, they are often dismantled, and the filter basket, pintles, and o-rings are replaced where required.

They are also flow tested and charted before cleaning, and again after cleaning to compare and check the results.

Again though, the K-Jet injector is a much simpler, and different beast. Yes, it can be ultrasonically cleaned, but one or two baths should do it, and obviously they cannot be pulsed on and off. I'm not sure if they can be back-flushed.

I've not had them done in Sydney, but have hear dof this mob: A & E Mobile Mechanics & Fuel Injector Cleaning Service

I'm not sure what they are like.

I can get D-Jet, and K-jet injectors at very goor prices if anyone is interested. just shoot me a PM.
 
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Styria

Styria

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Hi Fotografa, thanks for your response. I personally am not all that familiar with the D-Jet system. I know it is quite a bit more to service/ replace parts than K-Jet, but have not had any involvement.

Quite handy to know that you are able to supply spare parts for our vehicles and I shall certainly keep that in mind.

BTW, when I was referring to injectors from after market suppliers, I am referring to the Bosch brand. I am not aware of any other K-Jet injector manufacturers. Regards Styria
 

TJ 450

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It has been said that they can't be cleaned, only tested. I purchased a new set for the 6.9 and the difference was profound. It may also be possible to run some pressurised solvent through them to dissolve varnish, but backflushing them to remove debris would be near impossible.

Regarding brands, Bosch is indeed it for K-Jet injectors... there are no other manufacturers. They are identical to the ones supplied by MB, although the genuine versions may be subject to tighter tolerances. They should be readily available locally, as many vehicles other than Mercedes use them too.

Tim
 
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BenzBoy

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The Spirit runs K-Motronic. I replaced the injectors with the Bosh recommend ones and they upset the smooth idle. Bosch recommended returning the originals to them for cleaning and they were then re-installed. They were happy tp take back the replacements and refund the cost. Idle was again smooth. I think there may well be finer tolerances for the originals but how Bosh cleaned them I do not know - they were not very forthcoming on information about either the injectors or the work they did to the fuel head on the Spirit other than to fix and give a most modest bill.
The price difference between Crewe Original and Bosch replacements is enormous - and maybe not all of the slack is taken up with profit. It appears that the original may be different despite bearing the same part number.
Perplexed? Same here.
Regards,
Benz-Boy
 

s class

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styria, I have never had K-jet injectors cleaned. My injection specialist refuses to clean K-jet injectors, saying it doesn't work. He tests them, and inevitably, by the time one goes for the test, they almost all fail. Now days I don't even bother with the test, since the test costs 25% of the price of a new injector from MB. He did ultrasonically clean my W140's LH-jet injectors. The cleaining of LH injectors costs more than replacement of K-jet injectors :eek:

Here's the latest I have on K-jet injectors :

I've been getting trusty rusty ready for the Annual meet of the MB club of South Africa. This year its being held in the town of George, about 1200km from me.

OLD INJECTORS :

6point9_fuelsystem_11Apr09b.jpg

NEW INJECTORS AND CLEANED BITS :

6point9_fuelsystem_18Apr09b.jpg
 

s class

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further comment - here I can get injectors for the equivalent of about US$20 from MB - much cheaper than Autohaus or any other source.
 

Fotografa

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Regarding brands, Bosch is indeed it for K-Jet injectors... there are no other manufacturers. They are identical to the ones supplied by MB, although the genuine versions may be subject to tighter tolerances. They should be readily available locally, as many vehicles other than Mercedes use them too.

Tim

The are not identical the ones supplied by MB, they ARE the ones supplied by MB. Bosch is the OEM supplier of almost all of the fuel-inection parts in your Mercedes.

No tighter tolerances on the "genuine" ones, they are the same item, from the same production line.
 
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Styria

Styria

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Hi everyone guys, I would still pose these two questions, viz.,

1) Is there any truth, as far as anyone is concerned, that even new ones (whether genuine or after market - all made by Bosch) need to be put through a spraying and leakage and pressure test ? This was a procedure deemed essential by New Star Motors at Taren Point. I am not sure if they're still trading under that name and whether, in fact, ownership has changed.

2) Why would a very, very experienced Mercedes Mechanic insist that after market Bosch Injectors are crap ? Not my words, but his. Regards Styria
 

TJ 450

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I wouldn't have thought so, because surely they are tested before they leave the factory.
However, since there is an element of doubt cast over the situation, I wouldn't hesitate to get them tested for peace of mind.

I was aware that there was no difference as far as the injectors are concerned, but it may be possible that the ones boxed as genuine may be tested again by Mercedes. That's what I would like to think, particularly seeing as the Bosch packaged versions have been considered crap.

FWIW, there doesn't seem to be any issues with the new Bosch packaged ones I purchased for the 6.9. I think I will have them tested before I install them though.

Tim
 
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Styria

Styria

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Hi TJ450, I would imagine that you bought after market units as well. I mean, really, why would you go to MB for what may well essentially be the same product, yet you'd pay that much more for it. It wouldn't be sensible, and I for one would certainly take the chance.

With Gleaming Beauty, at the time of the valve grind and de-coke, I had already fitted four new ones to the left bank previously, and the right bank received new ones when the heads removal was completed. I did not have the new ones tested - put them straight in although I suspect that I may have one leaking unit now on either bank. Once I have recovered from the latest mishap (cooling), I will pull them out and have them tested. Regards Styria
 

WGB

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Hi TJ450, I would imagine that you bought after market units as well. I mean, really, why would you go to MB for what may well essentially be the same product, yet you'd pay that much more for it. It wouldn't be sensible, and I for one would certainly take the chance.

With Gleaming Beauty, at the time of the valve grind and de-coke, I had already fitted four new ones to the left bank previously, and the right bank received new ones when the heads removal was completed. I did not have the new ones tested - put them straight in although I suspect that I may have one leaking unit now on either bank. Once I have recovered from the latest mishap (cooling), I will pull them out and have them tested. Regards Styria

Maybe a bit of extraneous material found it's way in when the car was dismantled?

Bill
 

Andrew280SEL

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I bought the "aftermarket" boxed version of the K-jet Bosch injectors for my 280.

Although I didn't have them tested before installing, they seem to be fine as they made a very nice improvement to the car's running and I can't complain at all.
I guess you really do take a chance by doing it this way, but considering how relatively cheap the K-jet injectors are I wasn't worried myself.

And I guess truth be known, once they arrived I just couldn't wait to get them in the engine :)
 
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