The new gen V6 and its timing chain

[Guest]

While waiting on the final results from Chevy on the cause of a 3500 powered Pont Montana timing chain failure, and recalling a 3900 G6 owner mentioning a bent valve incident under warranty, I thought I'd do a little digging.

Those of us who have been in close proximity of the timing components of the 3500 and on V6 noticed that the timing chain appears to be anemically thin. Some are aware of the timing chain problems the early 3.6 DOHC motor has had and and appears to still be having.

The chains between the engines appear to have a similar size link and width. I mentioned some time ago that when installing a balancer on a 3500 GM requires two balancer bolts, one to install the balancer at full depth and a second that replaces the first and is torqued into place. My suspicion is that since the smaller timing gear can be removed by hand at least on my 3900 instead with a puller, there is increased risk of it slipping under load if not torqued properly. I read of such a slipping incident a moment ago on the web occuring in a Malibu that damaged the exhaust valves which so far are the only valves to have been damaged in the Montana that I spoke of earlier.

Below is an interesting read about the 3.6 woes for those aspiring to be 3.6 swappers:

http://www.gminsidenews.com/forums/f21/07-cadillac-srx-10-000-miles-failed-timing-chain-61965/

[IsaacHayes]

So is it a cause of stretching chain or improper re-assembly?

[Joseph Upson]

So is it a cause of stretching chain or improper re-assembly?

Stretching chains trip the engine light, improper assembly is an artifact of the mechanic replacing them.

The 3500 engine with the timing chain issue turned out to have been hydraulic locked during a fuel injection cleaning service according to the report from chevy today.

[Superdave]

Morse makes all GM's timing chains iirc.. Usually a very high quality piece, make to last atleast 100,000 miles.

The thinner ones do appear quite a bit weaker than the old design.. i still have my failed one hanging around.

[rsisbetter]

so, is it as easy as swapping in a (the) strongest 96-99 3400 timing chain? or an oem replacement?

[Superdave]

so, is it as easy as swapping in a (the) strongest 96-99 3400 timing chain? or an oem replacement?

Yep, i have a '99 chainset from GM in my 3500.


the only problem i ran into was the chain dampener or whatever you want to call it.. the newer one was too fat and rubbed the chain, aftermarket ones for a 99 3400 were the same way. So i took the stock 3500 one and shaved like 1/8" off each side and it fits/works perfect.

[rsisbetter]

hmm, well that seems to be the best solution to the problem then! and cheapest!

[Joseph Upson]

While waiting on the final results from Chevy on the cause of a 3500 powered Pont Montana timing chain failure, and recalling a 3900 G6 owner mentioning a bent valve incident under warranty, I thought I'd do a little digging.

The engine was hydraulic locked during a fuel injection cleaning service. Some of the services being offered for vehicles today are purely profit driven as the engines are made so well along with their components that such a service probably shouldn't be considered until about 100,000 miles, especially given the fuel quality thanks to all the additives. I may be mistaken but I believe ethanol by nature has a cleaning effect on injectors since some techs years ago actually used alcohol to clean them.

And for another plug, except for those vehicles that really need it, I wonder how much changing oil every 3000 miles or 3 months is contributing to the oil consumption in this country when the owners mauals and oil life monitoring systems are recommending upwards of 7000 miles or more. Cars are lasting much longer than many are keeping them for even when they haven't been properly maintained.


For those of you who can't relate or think it'll never happen to them, I've been getting in the gas line as early as about 5:30 am so I don't end up stranded on the side of one of Atlanta Georgia's roads lately.