w219 om642 tapping noise

[john2k84]

Ive noticed a tapping noise coming from the engine, sounds a lot like a hydrolic tappet going. It sounds louder when im close to another car or wall. I did a little investigation with a stethescope and was sure the tapping was coming from number 1 injector. I replaced the injector today fitted a new injector seal and stretch bolt, made sure eveything was clean clean clean but the noise is still there.
anyone else come across a issue like this?

 

[BlackC55]

Is it like a ticking noise?

 

[john2k84]

sorry yes its more of a ticking then a tapping. can here it at idle but seems to fade away around 1500 rpm

 

[BlackC55]

It is probably coming from the bottom end of the engine. It is a fairly common issue and you MB dealer will probably contribute towards the cost of repair if your car is out of warranty. Get it listened to by a MB tech.

 

[john2k84]

yep heard about the front main bearing issue with these engines. But i was in doubt about this being the cause as i had to change the top aux belt idler and ran the engine with the belt off and the noise was still pressent.Am i correct in thinking to diagnoise this problem the noise should go with the belt removed.
also seems more of a top end tick/tap noise rather then a bottem end knock.

 

[BlackC55]

It could also be the timing chain has stretched too. Not common but not unheard of. It can cause some strange top end noises.

 

[autopian]

hydraulic chain tensioner maybe!

chris

 

[john2k84]

cheers for the input guys. I've never had to test a chain to see if its stretched, would it be as simple as measuring the movement at the chains least tensioned point. Also were about is the chain tensioner situated can it be removed externally or do i need to remove timing covers.

 

[john2k84]

has any one got a overveiw of the chain set up for these engines, like from a mercedes parts programe ?

 

[BlackC55]

The best thing to do is to see if all the timing marks line up. Rockers off etc. You will need WIS for th eworking instructions.

 

[john2k84]

Little update. Removed the o/s head rocker cover yesterday evening didn’t remove the n/s before as rain stopped play. Couple of things I noticed with the cover off were when the cam lobs were pointing up I could move the valve rockers around on there seat they seemed to be loosely positioned. Seemed a bit odd to me as I thought the rockers should be in contact with the cam as it spins 360 all the way round there for keeping them from moving.
Also had a quick look at the chains they seem to be good. Obviously haven’t got round to checking the timing marks but what I did pick up on was when looking at the chain I could grab the chain on the top sprockets at move it forward and back. Sorry bit hard to explain but the slight movement (3-4mm) was if looking at the sprocket face on I could move the chain in the direction of front to back of engine.
Another observation was I could push the hydraulic chain tensioner guide against the chain a little harder and the tensioner piston would push out roughly 5mm more to take up the slack.
Don’t know if there any thing to be concerned about here just thought id post my findings so far.

But I’ve still got a concern with injector 1, should have bought a new one but I got a recon one instead (was a case of quicker and cheaper). It’s just all the other injectors have literally twisted and come out. In comparison to when I replaced injector1 which was a complete bitch to come out, due to all the coke and carbon around it. Could have been a case of a poorly seating injector replaced with a noisy one.
Anyway gona get home from work tonight and check the timing.

 

[john2k84]

anyone got the torque setting for the cam cover bolts?

 

[john2k84]

Got Both covers off last night and spun the engine round till the timing marks came up.
pulley set at 0 degrees TDC.
(crank pulley)

This is the mark on the N/S head.
(Inlet cam shaft sprocket)

And this is the mark on the O/S head.
(Exhaust cam sprocket)

Almost looks like its a whole tooth out .
Took another photo with a 2mm alen key resting on the O/S head to show were the mark should be.

can anyone confirm the chain has stretched beyond its tolerance?

 

[BlackC55]

Has the right hand side of the chain gone slack when set to TDC?

 

[john2k84]

sorry was that the offside bank or nearside

 

[BlackC55]

Ns

 

[john2k84]

I can only get access to the chain from the top I did try and remove the chain cover but got stuck with a tight crank pulley bolt. Got any tips on undoing it?

The chain seems pretty torte to me. I can lift the chain a few mill off the sprockets and it will always sit back on it nice and snug.
Same goes for the chain further down on the guides it will have a little movement in it but will always ping back into shape.
Only way I can describe it is it feels very similar to how a cam belt is tensioned.