2003 mc ls 3.4 Is mine timing chain.. a belt or chain? And what is the lifespan of it? I have 109,000miles on the car. At what point should I get a new one?

 

It has a timing chain. Typically, OHV (Overhead Valve) or Cam in block motors have a timing chain, where as DOHC (Dual Overhead Cam) motors have a timing belt because the motor has 2 cams (if it's an inline motor like an I-4, I-5 or I-6) or 4 cams (if it is a V block motor, V6, V8, V10, V12). As far as life, I'm not real sure on life, all I know is in my '89 Buick LeSabre with the 3800 I had 305,000 miles without timing failure and that motor has a chain. I know timing belts usually last 40 to 60,000 miles before they need to be changed. However, on my '06 Aveo LT, the recommended changing interval for the timing belt is 30k miles.

 

Thanks for the info.

 

You'll likely never see the timing chain break on these cars- especially with stock springs and such. It does stretch quite a bit, but there is a tensioner that presses on it to maintain tension. Eventually the tensioner will wear out (its just a simple spring and block design)- and that will be the point you'll need to replace it. But I haven't seen a lot of 3800s ever need this done- the couple I have have had REALLY high mileage (or had high rate valvesprings and an aftermarket cam).