Toyota Yaris snapped timing chain - Mike Williams
At the beginning of this year my wife's 1.0 Yaris developed a short rattle, lasting no more than 1-2 seconds when the car was first started in the morning. During its 2nd year / 20,000 mile service, she asked for the noise to be investigated. The garage diagnosed a faulty timing chain tensioner and said that this was a known fault, they said that they would order the necessary parts.

Three weeks ago they fitted the parts on a Monday, we got the car back on the Wednesday. Thursday morning it started OK (no rattle), Friday morning OK, Friday afternoon at 4000rpm on the overrun the timing chain snapped and scrambled the engine.

Since then the garage have been, 'obtaining Toyota's permission to rebuild the engine'. They now have a new 'short' engine and are swapping serviceable parts from the old to the new motor.

The garage says that they are completely mystified as to why the chain should snap and that the damage is so great that there is no way of telling what caused the breakage. They deny that it could have been due to their work in replacing the defective tensioner parts.

The Yaris is a new design with a new (VVTi) engine; my wife's car is just over two years old. If the VVTi engine has a tendency to break timing chains then Toyota have a real problem on their hands. Has anyone else experienced, or heard of problems with the timing chain?

Re: Toyota Yaris snapped timing chain - Alvin Booth
I have never heard of a timing chain snapping but then again not many cars have had them as I recall. I know they are now fitted on Vauxhall Ecotek diesels and also I believe on the latest Ford diesel engine and I recall Nissan having them.
It makes you wonder if it was perhaps the camshaft seizing up which caused it to snap. Another possibility is a faulty chain.....
They would certainly take some breaking I imagine.
I assume there is a 3 year warranty on the Toyota and this is why they are accepting responsibility??
Likely cause. - David Woollard
If there are no other conclusive thoughts I'm sorry I would have to go for one or more retaining bolts left loose/working loose. This could allow the bolt or whatever it should have retained to fall off into the chain gear area. At such a low mileage it would likely take such an event to break the chain. Having said that if the cam seized for any reason I guess that would also snap the chain.

I'm sorry but it is just too muck of a coincidence that this happened just four days after the work.

I'm rebuilding a Land Rover engine at present with a timing chain arrangement. This had suffered a fatal engine event mainly involving the crank bearings. However one of the little delights I found on stripping it was two lock washers in the sump...where from? Soon solved. They should have been on two bolts holding a timing chain "slipper" guide within the timing case. The bolts had come out and the slipper had fallen down into the bottom of the timing case........ on the way it had obviously done a few turns round the timing gears because there were several teeth missing and the chain was stretched.

This land Rover is a low reving heavily built unit and just escaped fatal damage from this source....... but I bet, with the missing teeth and slipper guide, it wouldn't have gone much longer. With such a lightweight precision engine as the Toyota any components falling into the timing gear at 4000rpm would easily do what you describe.

On a more general note the oil needs changing at 5/6000 miles or 6 monthly on an engine with a timing chain...well any engine really.

Re: Likely cause. - John Slaughter

Apart fom the unlikely event of a faulty chain then it just has to be the workmanship of the repair. After all how amny engines do you know that have soldiered on for years with rattly timing chains? This has to be a catstrophic failure to cause such a sudden break up.

Blame the workshop! - David Lacey
I am with you on this one David. You just don't hear of modern Toyota engines 'breaking' do you?
This one smells like sloppy bonus-led workmanship to me.



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