hello- i've searched the net and this site for info regarding timing chain replacement on my hummer.
all i can find is info on 2005-7 h3's.
did GM change anything on the 2010 ? it seems to be a major PIA from what i have read on earlier h3's.
the chain rattles on start up for about a second ,would like to replace tensioner and chain before it gets worse.
has been doing this for 6 months.

 

The I5s are all essentially the same using the same special tools regarding the timing chain.

How many miles does your H3 have?

Paste from an old post of mine:
"The Atlas Series engine has hydraulically actuated timing chain tensioner that requires the oil pressure to first come up to add the required tension to the timing chain. Over time the chain will stretch, but the tensioner has ratches that will eventually allow it to click over to the next position to correct for the slack in the chain. Sort of like self adjusting brakes worked.

When you first start the cold engine, if the chain is loose and before the oil pressure can come up to take up the slack, the chain may contact the insides of the front cover. It sounds like a rattle that immediately goes away.

What is happening is the chain is loose enough to slap but not yet loose enough for the tensioner to click over to the next position. Not all will do this, but a bunch can for a while. If this persists for a long time, you may have a timing chain that stretched too far, or tensioners that are worn and need to be replaced.

GM TSB 06-06-01-017G covers the revised cylinder head and timing chain service procedures for these engines.

Many/most will tell you this is normal. I would say it is more expected than truly normal, but it is not a big deal IMHO. Life is good if this is all you are worried about."

 

thanks for the reply but i am aware of the hyd. tensioner.
i've read that the oil pan has got to be removed to access the bottom front cover bolt,and to do that the front axle has to be lowered ?
i have replaced several timing chains in the past (not on H3's) and were fairly simple jobs.
has anyone on this forum done this job ?

 

by the way,my hummer has 97,000 miles and is only driven by my wife.

 

At those miles, IMHO you got too much time on your hands, I would consider it normal.

All the GM repair manuals are on line free for review. Link below in blue. Yes people here have done it and all the front cover bolts are out in the open for easy picking after getting everything else out of the way.

3.7L Engine Manual

 

thank you sir.
too much time on my hands...HUH !..i'ma retired millwright from goodyear/dunlop .
installed and repaired industrial machinery for 35 years.
BUT....sooner or later that chain will skip a tooth or brake.
timing chains should last at least 150,000 miles without any noise.

 

There are possible other causes, simple one is a defective oil filter or wrong size oil filter.

Has the oil been changed since the start up noise started?

Good luck. Let us know how it goes.

 

Engine Oil Filter Study

oil has been changed pennzoil 5-30 syn.,NAPA GOLD filter