Can faulty CDI injectors be diagnosed on STAR/ bosch service centres?

[martin_sv]

Hi,
Bought a 06 320cdi clk few months back having read what super smooth engines they were. Well it's certainly very smooth indeed but I'm dissapointed with the Diesel hammering type noise that is evident during acceleration up to about 2K revs max. Both non merc diesels I've owned before were much more subdued. However It's Nice and quiet and pretty much unrecognisable as being a diesel once I'm above 45-50mph. Searching online suggests I could be getting some pre-ignition and that drippy or otherwise worn injectors could be the culprits. I believe a full set of new injectors would be pretty pricey (??anyone know??) so am keen to learn if diagnostic machines can identify the performance level of each injector, oh yes mileage may be of significance and is 126000miles with reasonable service history but from about 50k onwards this has been non merc or known merc specialists,
Martin

 

[E270 Owner]

Get a leak off test done on Star to show the condition of the fuel injection system.

You can do a quick leak off test without Star to see if any of the injectors are faulty.

The above wont necessarily show noisy injectors though only those beyond operational limits.

They would probably be better off tested/serviced/overhauled @ £15.00 to test up to @ £70-80 to repair/overhaul for each one.

 

[Simzy]

My diesel is quite loud . Although I like the sound it can make you think there is an issue. I'm now of the opinion that if it drives fine and there are no faults then you should not worry. I have heard quite a few Diesel engines since I got mine and I can say that they all have that louder ticking type of sound, much nicer that petrol IMO ..

 

[martin_sv]

I'm definitely not a fan of the diesel "tick". Suprisingly the alfa 156 JTD I ran (and still have) was hardly noticeable at all. In this case the diesel noise is masked rather than not there. Alfa include a "resonance chamber" in the induction tract and this produces a nice throaty roar under acceleration. It was one reason why 7 years back I chose it over the theoretically more sensible buy of a 2litre ford focus---it had the dreaded diesel noise in spades. Unfortunatley Ididn;t test drive the cdi for long enough in slow and stop start traffic situations as I was keen to see how quiet it would be at motorway speeds (and was duly impressed), I have even thought of swapping for a 320 petrol as it just sounds crude and reminds me of a bus at town traffic speed. I will try and get the injectors checked out as I'm hoping it may quieten things down and also improve the (for me) dissapointing mpg. Under 33mpg from a tankful brim to brim where 320 of the 400 miles before the light came on were at steady cruise speeds, I've had 27mpg from my Sl350 for the same runs, in both cases I'm cruising at 80-85mph gps speed where possible, --- unrestricted roads of course!.

 

[Simzy]

I'm definitely not a fan of the diesel tick.

Then a Diesel engine is not for you .

 

[E270 Owner]

Fiats 2.4jtd sounds nice with the chamber as standard gives a deep note, the 1.9jtd's fitted to GM and Saabs not so much out side of the Alfa marque but they sound much quieter than Fords Spanish castanet performance clattering engines.

MB's CDI engines are not the long life bullet proof engine, some will tell you they are, but poor design and serviceability make the simplest task a high risk endeavor eg: (removing injectors) the piston knock problem and ingesting swirl flaps and overpriced parts can make for some expensive basic overhaul and repair bills compared to other manufacturers.

Now that said I have run a 156 2.4 jtd to Spain before from London and done the same trip in an E Class w211 320 CDI
I know what wheel I prefer to be behind for comfort and less stress, but I wish the 156 was on a trailer behind me for those lovely mountain roads and bends.

Cant have everything,................ so whip out those injectors and get them overhauled.

 

[martin_sv]

Yes, it's the comfort and less stress whcih led me to the clk as I now have a regular fast roads 160mikes journey to the west country and I'm getting old and like to feel relaxed over longer trips. For this role I'm very happy with the cdi but I was not intending to keep the alfa for all my running around short trips back home which because of the bus like noise quality I have done.
Trip to a local indy beckons for injector checks I feel!
thanks for all the inputs

 

[dubsR33]

sorry for stupid question but when you guys say on STAR, what does that mean?
Cheers and sorry

 

[martin_sv]

As the thread starter I ought to jump in with a reply. Star refers to the mercedes motors' group diagnostic and servicing machine used by all official merc garages and many independants who specialise in mercedes/smart. I added the word servicing machine because it can be used for a lot more than just reading diagnostic codes. It can test just about any electronic and hydraulic based system within the vehicle and for certain jobs eg replacing the SBC braking system pump which was fitted at one time to SL & E classes amongst others ( never the CLK though) is (from what I've read) the only way the job can be carried out.
HTH
Martin

PS As it sometimes gets asked, they cost plenty of dosh and have annual subsriptions to cover updates. They can sometimes be purchased secondhand and there are also Illegal chinese clones which appear on the web/ebay etc. Star can be made to run on a laptop providing it has a serial port. As there is plenty to learn in just what they can do, the skill and experience of the user also comes into it.

 

[dubsR33]

thank you for your answer