[Itsamoto]

So I'm staring down the chain job right now -- I have 3 24v engines in front of me -- all different mileage, and probably two of them are on original chains. Now -- I can see a variance in wear to guides -- but I'm curious/dubious about the chains. Do they really stretch that much that they need to be replaced? Seems like the job of the tensioners more than makes up for the minute amount of chain play. This chain looks very strong - I've seen smaller heavy-duty chain where the pin holes elongate (across the whole chain) and thats how the chain stretches out.

Cost wise - its about $100 cheaper to just replace the guides and leave the chains alone. Do people just replace the chains because thats how the "kit" is sold -- or is there a good reason to replace them that I'm missing? I doubt this chain would ever break on it's own -- everything else is much more likely to degrade around it before the chain goes.

I'm on the fence on this - and would like to know what others think.

Do we have any empirical data on the degradation of these timing chain components?

Anybody have brand new chain - uninstalled that can be measured as a control/standard?

[albertr]

If it's just a $100 extra, I would replace it "just in case". It would be real pain to get to the chains again on VR6 should you need to replace them in future.

-albertr

[Cole]

I honestly think "chain stretch" is the term most of these mechanics use when they can't solve the timing issues usually associated with the stuck cam adjusters.

I fear a lot of unessecary timing chain jobs have been done on these vans.

I measured a brand new chains against a 152k mile chains and they were identical down to .00. If a chain with 152k on it doesn't show any notable deviation then I doubt any of these chains actually "stretch".

Wearing out the pins or between the pins could be another issue, especially if tension has been off.

All that said. It's a whole lot of work to access that chain. Best to just put new parts on while you are there.  Neglecting a $100 part could cost you $3k in effort later.

I'd also just pony up and replace the "crack pipe", thermostat housing, thermostat, temp sensors, and install a trans cooler while you are in there.

[Itsamoto]

It's certainly a slippery slope when you start putting in new parts just because "you're there". It doesn't take much to blow the budget -- especially if you're strictly using OEM or better parts only. If I add in gaskets, sprockets, bearings, etc -- it gets pretty darn close to just start looking at new crate engine. It's not so much the $100 (actually about $200 when your Canadian with no free shipping, 20% exchange and 10% duty) of savings -- I would prefer not to replace perfectly good OEM parts with lesser quality "selected" parts in a kit.

But, I'm glad to see that the chain measurement was made. Gives me some incentive to compare the 3 sets of chains -- and all other components as well.

[Cole]

I'd love to see more data points for chain measurements. Hopefully it will blow the myth of chain stretch out of the water here.

The items I suggested are common failure points that are cheap and already "off" anyway. You might add $200 more to the cost of the job but save lots of effort or a tow bill later.

[albertr]

While not being measured by very sophisticated or precised techniques, my 145+K upper chain looked about the same length as a new one. Chain links felt a little bit loose, thou. And width was measured to be somewhat wider than the new chain, although it might be because of the different chain maker - Sasch vs Iwis.





-albertr

[albertr]

Itsamoto,

When you have chains off, take a closer looks at intermediate shaft sprockets.
While outer surface of the smaller sprocket (for upper chain) on my AXK motor looked fine, the inner surface  showed some deep groves eaten out by the old upper chain, see below:





-albertr

[Christian]

I agree with Cole as far as the chain stretching. For the intermediary gears, I've seen a few of them heavily worn down. The intermediary gear in my '01 barely resembled a gear. I only have crap photos of it on the van, unfortunately - no comparison photos. I think the intermediary gears can wear and the chain will hop a few teeth.

[robinson1509]

I agree the tensioners should compensate for strech and wear. The weakest link is the plastic guides. However, the time and effort it takes I think a hundred dollars is money well spent.