Replacing Chain Guides

[BYprodriver]

Originally Posted by thom4782

My 'left you stranded' post leads me to think more about preventative maintenance. Specifically, I'm wondering about the chain guides.

As I understand it, there are two types in my car: variocam rails which are brown and chain tensioner rails, which are black. I have a couple of questions.

1. In the absence of any symptoms, like plastic particles in the oil filter, should one replace these items proactively?
2. If so, at what mileage should one consider doing the work?
3. Can one replace the chain tensioner rails without splitting the case?

I've looked and haven't found a post on point. Any guidance would be appreciated.

Thanks

The "Vario-Cam rails" chain wear pads often have enough wear at 70,K miles to warrant replacing with the far better & longer lasting updated replacements which cost $30 per side. The black chain rails should wear much slower & usually are ok to 100,K but check the wear pad where the the chain tensioner contacts it. They can be replaced without splitting the case.