Knocking D5

[spee]

My D5 (115k) engine is knocking on acceleration.

At first I thought it was the leaking injectors I've recently had replaced, but these have been sorted and leak checked, it's not them.

So, it's as normal under normal / part throttle, but push a little harder in gear and it knocks/taps (and it's loud). It sounds alarmingly similar to when the bottom end shells went on a previous car of mine (not a volvo).

Obviously I'm hoping it's not the bottom end bearings/shells. I can't believe for a minute it is, I've trawled this site and many others and not found a single bottom end failure on the D5, but it could be a first I guess.

Any suggestions of what to check or any other problem that would cause a loud tap, rising with revs under load will be great!

Oh, the oil level is fine.

Edit - As a side note, it's running well! Tickover is ok at a solid 700 RPM and pickup (other than the knocking) is good.
If this was a petrol engine, I'd think pinking/knocking, I'm not sure if diesels suffer from this?


Gareth

[carl4u44]

Did this noise come about after the injectors were replaced? Are they the same class? Were they recon'ed?

[spee]

Originally Posted by carl4u44

Did this noise come about after the injectors were replaced? Are they the same class? Were they recon'ed?

After injector replacement. They were rebuilt/recon.

G

[carl4u44]

Im not too sure if this stands correct but classes 1 and 3 cannot be rebuild or recon apparently they are never the same after. I cant say for sure and maybe some else can clarify.

I too have a mild knocking on idle which seemed to have appeared after the second injector was recon'ed but mine was a class 2.

Your symptom could be a sign of injector knock which is common across all common rails I believe.

[spee]

Originally Posted by carl4u44

Im not too sure if this stands correct but classes 1 and 3 cannot be rebuild or recon apparently they are never the same after. I cant say for sure and maybe some else can clarify.

I too have a mild knocking on idle which seemed to have appeared after the second injector was recon'ed but mine was a class 2.

Your symptom could be a sign of injector knock which is common across all common rails I believe.

I've been reading up on diesel injector knocking since posting this oddly enough, sounds like my problem to be honest, all the symptoms seem to match.

I'll read up more, thanks for the advice.

G

[carl4u44]

Just a little note to add:

From a previous leak off test I was told that my injectors 1 and 3 needed replacing. So I used my brand new injector and replaced number 1.

Now I have noticed and others may wish to test this too that upon putting a long screwdriver to the top of each injector and listening with my ear each 'note' from the injectors.

The previous numbers 1 and 3 had a 'high dong' sound to them and these were said to be bad.

Injectors 2, 4 and 6 have a nice 'suttle low soft tick' noise.

To confirm my brand new (class 2) injector seated in number 1 also has this nice suttle tick instead of the 'high pitched dong' noise which sounds a bit like throwing a full apple into a metal bin.

Perhaps others could test this little theory.

My thumping noise too has quietened down a little too I think but im all ears on it for now!

[spee]

Originally Posted by carl4u44

Just a little note to add:

From a previous leak off test I was told that my injectors 1 and 3 needed replacing. So I used my brand new injector and replaced number 1.

Now I have noticed and others may wish to test this too that upon putting a long screwdriver to the top of each injector and listening with my ear each 'note' from the injectors.

The previous numbers 1 and 3 had a 'high dong' sound to them and these were said to be bad.

Injectors 2, 4 and 6 have a nice 'suttle low soft tick' noise.

To confirm my brand new (class 2) injector seated in number 1 also has this nice suttle tick instead of the 'high pitched dong' noise which sounds a bit like throwing a full apple into a metal bin.

Perhaps others could test this little theory.

My thumping noise too has quietened down a little too I think but im all ears on it for now!

Well, mines been back, both injectors re-seated, still clacking.

So, back it went again, both injectors looked at, re-fitted, still clacking. I'm losing patience!

G

[spee]

Originally Posted by spee

Well, mines been back, both injectors re-seated, still clacking.

So, back it went again, both injectors looked at, re-fitted, still clacking. I'm losing patience!

G

It's still clacking so will be back in the garage tomorrow! My patience is shot now! It had better be sorted this visit!

[chiptivo]

Originally Posted by spee

It's still clacking so will be back in the garage tomorrow! My patience is shot now! It had better be sorted this visit!

Did they fix it.?

[Clan]

reconditioned injectors on a D% are a waste of money they have been proved time and time again to give this problem , the flow rates have to be accuratly matched to each other so ALL 5 are exactly the same , once they dismantle an injector this fine calibration is lost . Buying a new injector and pipe from the dealer matched to your calibration number is the only way ...