850 camchain rubbing cam cover.

[Brendan W]

Got chain rubbing marks inside the cam cover just at the entry and exit to the idler. Thought it was old history now not so sure.
Tensioner is free, new seals fitted. Chain length is good.
Could the idler be worn or is it possible to install it incorrectly.
Keep meaning to put some blue on the marks to see if it really is still happening.
No funny noises.
If a liquid gasket was used in the past would that do it ?

[tom203]

Remove the idler and check for slop in bearing/ bushing- maybe it looks OK at rest but starts to float under load.

[Brendan W]

Seemed fine at the top end job last summer.
How far do you go on the tensioner spring ? Maybe it's getting tired and another turn would help. I probably used the one turn by the book.
As it is it's silent at idle and I get the start of chain clicking with about 10 degrees of rotation backwards.
Now that I think of it I have heard the odd noise that was a bit more than clicky shim clearances.