From another recent thread here:
http://www.clubralliart.com/showthread.php?t=2431
The computer keeps track of how much the chain stretches over time. It will tell you when it is time when all the systems are working properly.
There is no specified interval to change the timing chain. Obviously if the motor was all apart for some other reason and you had more than 60k miles it would be a good idea to go ahead and do it.
There is also a tensioner and a couple chain guides in there that should also be replaced at the same time. There is also a separate baby chain that drives the oil pump. Early motors had a little oiler gizmo that didnt always work the best. I think this was mostly 2008 however.
It is a very involved job to change it all. The oil pan comes off, the whole side of the motor comes apart. There is not a lot of room to work in there. Lots of care needs to be exercised to get everything sealed back up properly so you dont have oil leaks.
Dirty oil seems to be the most damaging to the timing chain. Also it can lead to solenoids and valves not operating correctly to make the ECU think that something is wrong with the timing chain system and the proper alignment between the crankshaft and cams.
Dealer retail parts prices for the timing chain, guides and tensioner:
Tensioner Lancer, Lancer Evolution 2.0L $63.88
Timing chain Lancer, Lancer Evolution 2.0L $96.18
Chain guide Lancer; w/Ralliart; Slack Side 2.0L $11.48
Chain guide Lancer; w/Ralliart; Tensioner Side 2.0L $21.10
Also the oil pump chain is down in there too:
Oil Pump chain Lancer, Lancer Evolution 2.0L $120.52
Oil Pump Chain tensioner Lancer, Lancer Evolution 2.0L $77.50
chain guide Lancer, Lancer Evolution 2.0L $68.03
It is pretty much an all day job. The oil pan needs to come off along with the whole side of the motor. Here is a wonderful Engrish description from the factory tech manual:
If the vehicle equipped with 4B11-T/C engine continues the rough driving like competitive running*1, the amount of carbon mixed into the engine oil tends to increase. This can possibly cause the timing chain to gradually elongate. To prevent this, the function or logic monitoring the amount of elongation of the timing chain is integrated into the ECM. When the ECM detects the elongation of the timing chain, the warning is shown on the multi-information display of combination meter as shown in the illustration. This gives the driver the information that the visual check of the elongation of the timing chain is necessary. If this warning is continuously neglected, the timing chain can possi¬bly interfere with the other engine components, resulting in the engine damaged.
NOTE:
*1: The competitive running means the running that constantly repeats the cycle of the full opened position of the accelerator pedal and the full closed position of the accelerator pedal.
Timing Chain Warning Indicator:
