Can Timing Chains Break ?

[suprasteve1979]

Hi I have popped across from the supra forum for this one, hope you can help,

I went to move my mums 52 1.8vvti Avensis the other day and as it was about to fire up it died, when I crank it over now, the stater motor wurrs freely all belts move (aircon altenator ect) so the crank is definately turning, but it sounds like and enigine cranking with no timing belt as there is no change in picth from the starter motor as you normally hear from a car

I thought the belt may have just gone and wasn't too worried as I think all toyotas run non interence engines, but reading on in your forums it seems they are chain driven. Any ideas as chain breaks are or I would have thought very rare

Steve

[marama32]

Hi,

It sounds to me like it is the chain.

It is unusual for that to happen.

The Avensis does have a non-interference engine.

How many miles has it covered?

I have not heard of anybody having their chain go under 100k

Cheers

[suprasteve1979]

Thanks for reply it hasn't done more than 100k think its around 60k mark, I will check, odd for a chain to go so early or at all.

thanks again

will let you know for future posts

[Beagh1958]

To suprasteve1979,

Sounds very very odd for chain to go at that milage ( are you familiar with service history if not owner from new) sounds very low. But it can happen every now and again, in most cases you would have some sort of warning maybe a bit of chain slap (noise). Also possible you may have defective chain tensioner, but these are pretty much bomb proof. If you find chain has gone, when renewing parts make sure you renew chain guides & tensioner. Checked "Autodata" and engine is shown as non-interference as suggested by earlier posting. If taking on job yourself, make sure all debri is removed from engine down to the smallest metal particle.

Good luck, Beagh.

[igormus]

To suprasteve1979,

Sounds very very odd for chain to go at that milage ( are you familiar with service history if not owner from new) sounds very low. But it can happen every now and again, in most cases you would have some sort of warning maybe a bit of chain slap (noise). Also possible you may have defective chain tensioner, but these are pretty much bomb proof. If you find chain has gone, when renewing parts make sure you renew chain guides & tensioner. Checked "Autodata" and engine is shown as non-interference as suggested by earlier posting. If taking on job yourself, make sure all debri is removed from engine down to the smallest metal particle.

Good luck, Beagh.

Hello

when broken the chain -- it is disaster for the engine resulting full overhauling of short motor changing.

cheers

[Aamir2892]

2002. Im sure thats a belt, isnt it??? I dont think that the chains ever break becuase they are metal. My 55 i drive now has done neally 68,000 miles and never had the chain replaced. Dont they get changed at 100,000 miles.

[Beagh1958]

To suprasteve1979,

All vvti engines are chain drive bar-none. If your car has thrown chain it will empty your pockets.

Regards, Beagh.

[Black Knight]

A 2002 Avensis with 1.8L is a 1ZZ engine.

1ZZ Runs with a timing chain rather than belt

Earlier models (pre-2000 I think it was) were A-Type engines with a belt drive

A-Type engines are Non-interference

ZZ engines are interference engines.

It is possible for the chain to break but it takes a lot to break a metal chain. If that's the problem then I'd guess it's a result of something else.

Sounds like you aren't sure if the chain itself has broken. Sounds like the engine isn't straining against the normal compression in the engine if I'm understanding you correctly. Could be a broken chain but I reckon seized Cams or similar

[Q.S.]

A 2002 Avensis with 1.8L is a 1ZZ engine.

1ZZ Runs with a timing chain rather than belt

Earlier models (pre-2000 I think it was) were A-Type engines with a belt drive

A-Type engines are Non-interference

ZZ engines are interference engines.

It is possible for the chain to break but it takes a lot to break a metal chain. If that's the problem then I'd guess it's a result of something else.

Sounds like you aren't sure if the chain itself has broken. Sounds like the engine isn't straining against the normal compression in the engine if I'm understanding you correctly. Could be a broken chain but I reckon seized Cams or similar

Do these engines suffer with 'bore wash'? That is when too much fuel washes the oil from the bores and results in low compression. Have known this happen with other fuel injection cars but not sure if Toyota suffer too.

It usually occurs when the engine has been run from cold for a very short period like moving into the drive from the street, and then turned off. You then go to start it, maybe 30 minutes later, it gives a kick and then sounds like the timing belt has bust.

If you can determine that all is well on the valve gear side (everything turning as it should), this may be the problem and it will eventually start with some persistance and possibly full throttle to get plenty of air through and clear excess fuel from the cylinders.

[Beagh1958]

To suprasteve1979,

My apoligies, double checked disc, car is as stated by earlier posting interference fit. Do you have a friend or local mechanic who can pull cam-cover & see what if any damage you may have. Got to be quickest way forward?

Regards, Beagh.

[Jemmo]

Can I ask a dumb question here?

What's the difference between a non-interference and an interference engine?

I have a 98 Avensis - belt model so I'm wondering what that means for me.

[Black Knight]

A 2002 Avensis with 1.8L is a 1ZZ engine.

1ZZ Runs with a timing chain rather than belt

Earlier models (pre-2000 I think it was) were A-Type engines with a belt drive

A-Type engines are Non-interference

ZZ engines are interference engines.

It is possible for the chain to break but it takes a lot to break a metal chain. If that's the problem then I'd guess it's a result of something else.

Sounds like you aren't sure if the chain itself has broken. Sounds like the engine isn't straining against the normal compression in the engine if I'm understanding you correctly. Could be a broken chain but I reckon seized Cams or similar

Do these engines suffer with 'bore wash'? That is when too much fuel washes the oil from the bores and results in low compression. Have known this happen with other fuel injection cars but not sure if Toyota suffer too.

It usually occurs when the engine has been run from cold for a very short period like moving into the drive from the street, and then turned off. You then go to start it, maybe 30 minutes later, it gives a kick and then sounds like the timing belt has bust.

If you can determine that all is well on the valve gear side (everything turning as it should), this may be the problem and it will eventually start with some persistance and possibly full throttle to get plenty of air through and clear excess fuel from the cylinders.

Not that I've ever come across

[Black Knight]

Can I ask a dumb question here?

What's the difference between a non-interference and an interference engine?

I have a 98 Avensis - belt model so I'm wondering what that means for me.

If the cam-belt breaks chances are the cam will stop with the cam lobes will be holding valves open in the engine. The innertia of the vehicle will keep the bottom end of the engine turning though and hence the pistons pumping up and down.

In a non-interference engine it would just mean replacing the belt and retiming the engine.

On an interference engine the piston will smack into the valves bending them meaning they all have to be replaced at least and normally they'll break up and wreck the rest of the engine.

[SF695]

Can I ask a dumb question here?

What's the difference between a non-interference and an interference engine?

I have a 98 Avensis - belt model so I'm wondering what that means for me.

Anyone feel free to correct me, if wrong, but a none interferance engine does not experience broken or bent valves or damaged pistons, if the timing belt ,or rarely the timing chain breaks, due to the pistons hitting the valves. An interference engine however, has to have major repair done in addition to a new belt or chain. New valves, pistons etc.

It's more or less dependet on the physical compression ratio of the engine. On a high compression engine, the pistons can reach the valves, if not closed at the right moment, as happens when the timing belt breaks.

Except for that, it's pretty rare for a timing chain to break. They are not supposed to be changed once in a while, as is the case with a timing belt. They are supposed to last for most of the engines living time.