Knocking Injector

[Wee T]

I have a 2002 C270 Cdi estate which is knocking quite loudly on one cylinder.I had a new injector fitted by a local so called specialist but the knock still existed.He rekoned it was another injector but only one cylinder was knocking originally.Having lost faith in him I ordered an Injector and this morning I replaced what seemed to be the loudest injector,the knock still existed so I changed them over one at a time but the knock still exists.I have just read on here that some people rekon they need programmed to the Ecu and some people rekon they don't.It also seems to be the norm to replace the copper washers which I didn't do,I cleaned them and checked them for damage then re-used them.I cleaned all the seats before refitting each injector.There are no leaks on any of the pipework.Due to the current recession I can't afford to replace the full set.Has anyone any ideas and do they need programmed to the ecu.

 

[walsi]

 

[Wee T]

Injector

Now thats really helpful.

 

[walsi]

You cant just remove injectors and just put them back in without replacing seals and bolts unless you want to cause yourself a whole heap of problems with leaking seals. Is the noise not diesel knock?

 

[Wee T]

Injectors

I'm more used to working on petrol cars and messing around with turbo's etc.If I replaced the seals every time I removed an injector then i'd go through hundreds of them.How can I establish if it is diesel knock.

You cant just remove injectors and just put them back in without replacing seals and bolts unless you want to cause yourself a whole heap of problems with leaking seals. Is the noise not diesel knock?

 

[walsi]

Firstly diesel engines run at much higher compressions than petrol engines so the seals need to form a good seal so should always be replaced with new when an injector is replaced, they are only a few pence each.Diesel knock is a loud knocking noise like a rattle that is present on all diesel engines but is a lot quieter on newer comon rail diesels. It will get quieter as the engine warms up and will be louder in colder weather

 

[walsi]

Plus the bolts are stretch type bolts and should only be used once and then replaced.

 

[Wee T]

Knock

Well it's not knock then.It's just in one cylinder and it's constant warm or cold.The car ran quietly with no knock but while driving one day the knock just appeared out of nowhere.It didn't start then get louder it has remained constant.Right i'm off down town to get some copper washers.The bolts will have to wait as there is no local supplier.Thanks for educating me a bit.

 

[walsi]

Is it a hydraulic tappet then, that would be my next port of call. Get a long scredriver and move it along the rocker box whilst holding the other end to your ear. You will soon hear if it is a tappet

 

[Wee T]

Tappet

I never bothered to try listening to the tappets.I just assumed it was the injectors as thats what the so called Mercedes specialist diagnosed,ill have a listen to the tappets now before I run looking washers.

Is it a hydraulic tappet then, that would be my next port of call. Get a long scredriver and move it along the rocker box whilst holding the other end to your ear. You will soon hear if it is a tappet

 

[walsi]

How did your "merc specialist" diagnose it was an injector, did he put it on a diag machine or flow test them?

 

[Wee T]

Knock

Supposedly he did a flow test aswell as a diagnostic test.It's definately not an injector it's a tappet.I'll be paying the specialist a special visit.Just goes to show how good some of them really are.It makes me wonder if he even bothered to change the gearbox oil and filter like he was supposed to do.

How did your "merc specialist" diagnose it was an injector, did he put it on a diag machine or flow test them?

 

[walsi]

Hi ya, if he had flow tested the injectors they would have new seals and they would have proberly been recalibrated, that and a diag would have told him for certain if that was the prob, its not a cheap job so must have cost a few quid but he should have known straight away what it was just by listening. Some people have no morals at all. Good luck

Martin

 

[Wee T]

Knock

Thanks for your help.I'll be my own specialist from now on.

 

[Wee T]

Knock

I've now been to a proper Merc Specialist and he can't diagnose the knock but rekons it's in the head..We went to the main dealer and they rekon it's something gone wrong in the head aswell.So now the head has to come off for inspection.

 

[renault12ts]

Can I join in the love in? Who was your specialist?

 

[Wee T]

Specialist

I'd prefer not to name them but they are in County Antrim

Can I join in the love in? Who was your specialist?

 

[renault12ts]

Reply 7 more times then you can PM me. We can compare notes as to who we use.

 

[Olivier]

Is it a hydraulic tappet then, that would be my next port of call. Get a long scredriver and move it along the rocker box whilst holding the other end to your ear. You will soon hear if it is a tappet

What do you do if this is a tappet? Can you rectifye the problem , are they adjustable?
Cheers.
Olivier

 

[walsi]

Hi ya, the tappets are hydraulic so the only option is to change the offending one, they are not big money but the expence comes from having to pull all the injectors and remove the rocker box which if you have had a leaking injector can be a pig of a job. i have one that is occasionaly noisey but i can live with it. Have you done an oil change lately?? this can sometimes cure a noisey tappet

Cheers Martin