I have an 08 H3 with 3.7 engine, two days ago i was coming home from work and my engine started knocking, I took it to my mechanic and he told me the balance shaft timing chain sounds like it broke, the engine runs fine but it knocks. my question is can he replace the balance shaft parts and that will fix my hummer or could this cause more damage in other parts of the engine?

 

its on back of eng so either pull the eng or tranny to get it.. big job!!

oh, i wouldnt drive it around the block!

 

would this cause damage to other parts to the engine?

 

it reduces vibration and if you are knocking that sounds like stress on other parts, bearings??
dont know for sure but id not run mine that way.
im surprised the chain didnt get in the gears ? if it really is broke.

 

Do you happen to know which bearing it could possibly be?

 

I'm not sure what you are asking? If that diagnosis is correct, and you are asking if you can just keep driving it and fix it later whenever you get around to it, I would say that is not a good idea. Could you drive it to the Hospital when your wife is about to give birth? OK, but beyond that, park it until you get it fixed.

The chain did not break, the tensioner probably toasted and the chain might have jumped a sprocket tooth, so now it is out of time.

Here is some info regarding the I5s you may want to review, although it is about the 3.5L, the 3.7 is the same. Tech Feature: Straight Up Look at the Vortec 3500 Straight-Five Engine -

#242 below is the chain, #237 & 239 are the balance timing shafts, #243 is the tensioner

 

No I'm not driving it my mechanic was asking which bearing he should go after

 

If your mechanic's diagnosis is correct.... there is no "Bearing to go after", you pull the motor, replace the balance shaft timing chain and tensioner, and put it back together.

 

Would this make the engine knock?

 

Unfortunately my authorized Hummer repair center has never worked on a Hummer so I feel like I'm in this endeavor alone