Is there a mileage at which the chain tensioners should be replaced on a 2010 ford ranger with a 4 liter motor or do i wait until i hear bad noises and see plastic in my motor oil?

 

Mine has 114k and you can hear chain rattle good but it runs smooth so idk.Really don't think there is a replacement schedule.But maybe i'm wrong.

 

My 2001 has 83680.0 pampered miles - and the guide just went. So I would say it's anybody's guess

 

I have 185K miles on my 02 so far. I have not had any of the symptoms of bad timing chain guide at this point. I did change the timing chain tensioners at around 150K miles as a preventative maintenance measure but the old ones were still good. They are accessible without having to remove the engine. The rear one was pretty easy but the front one required a lot more work. I got the tensioners at a decent price online and am not sorry I did it.