Timing Chain Snapped On Idle

[jabran200]

My 1.0 yaris' timing chain snapped on idle, the car was having problems starting for a few days and the chain was extremely noisey. What I want to know is that is the yaris engine a non-interferenece or an interference engine? Because if it is a non interence engine then I might be able to get away with replacing the chain kit? If not then a rebuild will be the next best option as a used engine will never come with warranty but a rebuil comes with a guarantee.

jabran.

[moonstone mart]

Definately an interference engine - sorry :(

You may have gotten away with very little damage but it will need stripping down to check everything.

Mart.

[T V O R]

That has to be a first.

Never heard of a timing chain fail before. At least you had warning (the noise and starting) with a belt it would have gone with no warning.

Pity you didn’t take notice of it.

[dagbladet]

My 1.0 yaris' timing chain snapped on idle, the car was having problems starting for a few days and the chain was extremely noisey. What I want to know is that is the yaris engine a non-interferenece or an interference engine? Because if it is a non interence engine then I might be able to get away with replacing the chain kit? If not then a rebuild will be the next best option as a used engine will never come with warranty but a rebuil comes with a guarantee.

jabran.

What is the 'interference' 'non-interference' thing all about?

[DaveSR]

Something disengages to prevent damage to the engine ..... not sure exaclty what or how but that's all I know.

I'm sure someone will explain in a bit!

[Parts-King]

That is the first time I have ever heard of a VVTi chain snapping

Kingo

[eiriksmil]

That is the first time I have ever heard of a VVTi chain snapping

Kingo

Kingo, when should the chain be replaced? Got a note from Toyota saying the timing belt should be replaced on Toyotas every something miles. I can't remember exactly what it said, was too gutted of Toyota telling me to replace the belt I don't have

I've seen you've got some expertise on these things; is there a certain mileage, or a certain service? Thanks in advance

[Parts-King]

There is no time limit on a chain, it is based on min/max measurements

On a Yaris 1.0 You measure the clearence between the chain tensioner and arm, STD = 10-11mm MAX = 19.5mm If above max, replace the chain, also there is a procedure for measuring the chain gears, again if over max spec, replace

Kingo

[johnny01]

What is the 'interference' 'non-interference' thing all about?

As I understand it, if a timing belt snaps the 'top end' of the engine becomes stationary - valves etc - but momentum (and if you are in gear the motion of the car) keeps the 'bottom end' of the engine revolving - crankshaft, pistons etc. If an engine is termed as 'interference' then there is a possibility that the stationary valves and the moving pistons will hit each other causing obvious damage. Non interference engines usually have sufficient clearance between the valves and the pistons to prevent damage.

I believe most modern engines are 'interference' because of the need for increased performance which is easily achieved by higher compression ratios (ie; the pistons go nearer to the top of the combustion chamber) and the profile of the cams (the valves basically are very very close to the pistons - some pistons even have chamferred edges or cut outs where the valves open into, there's that little room inside a modern engine.)

Someone please correct me on this if I am wrong :)

Also - I've never heard of a timing chain snapping, I would be interested to hear more about the circumstances of this happening, ie; component failure? oil starvation? Weird...

[eiriksmil]

There is no time limit on a chain, it is based on min/max measurements

On a Yaris 1.0 You measure the clearence between the chain tensioner and arm, STD = 10-11mm MAX = 19.5mm If above max, replace the chain, also there is a procedure for measuring the chain gears, again if over max spec, replace

Kingo

Cheers, mate. But the 1.3 and 1.5 are also chain driven, right?