Help with om642

[TimHamnett]

Hi everyone,
I’ve got a bit of a problem with my Viano 3.0cdi 2006 with a v6 om642 engine. After replacing my water pump (coincidently) my engine developed a loud rattle that I’ve presumed was timing chain rattle. The tensioner was not particularly extended but with the sudden nature of the noise after not being run for a while I thought it the most likely suspect. I’ve replaced it with a good quality new one and put the front of the van back together but when I start it up there is still a rattle. Not as bad, but still there. The noise is the same with the auxiliary belt removed so that rules a lot of other things. The tensioner, before fitting the new one, after fitting new one, and after idling for ten minutes, remains in pretty much the same position, with non of the shoulder on the piston visible. It’s obviously compressed a little by being in contact with the guide but leaving plenty of movement spare to take up any slack. If the piston was all the way out, or even close to being I would presume it to be a stretched timing chain, but as it is, it’s got me stuck for ideas.
Thanks in advance.

 

[toteimerced]

Sounds like it’s time for a new timing chain unfortunately.

 

[TimHamnett]

Sounds like it’s time for a new timing chain unfortunately.

Well, maybe, but I’m confused by the tensioner still being well within its range of movement. By the look of it there’s another 8-10 mm before it reaches the end of its potential travel.
If it was sticking right out it would be a no brainer.

 

[toteimerced]

There is a possibility that the chain is worn, rather than stretched, or possibly the sprockets, which could account for the rattle.

 

[TimHamnett]

I suppose I’m still hoping for an easy fix rather than unknown quantities that can’t be seen.
I’m not really in a position to do a big strip down to find out at the moment.

 

[TimHamnett]

And the fact that the problem reared its head while parked up.