Yaris needing new timing chain after 4 years.

[DMZ]

Originally Posted by brbo

I would guess you are getting a noise, of sorts -

Not uncommon for newer vehicles (tiny little chains) when there is lack of maintenance, or the intervals of LOF are spaced to far apart....

With lack of necessary amount of oil, or poor oil quality causes higher oil temp causing the chain to overheat and stretch - and the slack in the chain can cause noise within the timing cover....

Cheers BB

PS 3/60 comprehensive and 5/100 PTO may only be a N.A. policy for Toyota

What usually happens is that wear on the timing chain gears allow for a bit of slack in the chain. The only symptom would be chain noise, like you mentioned. When the engine is rev'ed, there was a distinctive whrrrr that could be heard.

Eventually, the wear will be so excessive that the chain will jump the sprocket and throw the timing so far off that the engine will sputter out and refuse to start. This was a common occurrence on high mileage V-8's made in the 60's and 70's. The fix was to to replace the chain and gears which came in after-market kits.

Better technology has made timing chains much more reliable and long lasting. There are millions of Corollas running around with >150K miles with original timing chains and tensioners. I find it hard to believe that a 4 year old Yaris engine has a worn chain.