Timing Belt vs Timing Chain.

peasant

Slidey wrote: »

I have seen many old Sprinter (412's, same engine that is in the Korando and old SSangyongs) engines on 400k with original chains and very little rattle in them.

Yes, but those are comparatively old engines (and diesels on top of it) where it doesn't really matter that much if the timing is "a bit off"

Latest engines (mostly due to emissions restrictions) have to have precisely accurate timing or else the sensors kick up a fuss and you're limping home

Even the best chain will lengthen after a while (long before 400 k) and will then have to be replaced on a "sensitive" engine.

unkel

Whoah, hold on now you dudes are going too fast for me. Ok, so when a chain skips a tooth, on a modern engine that's bad. I got that. But does the chain not start rattling way before that, giving you the signal it's on the way out?

That has always been the reason I considered the chain superior to the belt. You don't have to worry about anything / know about anything. I mean a FIAT petrol needs a new belt every 30k miles / 4 years or something? 10 years and 100k miles on the Focus sounds decent but what if it snaps after 99k miles without warning?

beachlife

peasant wrote: »

Close ...but still wrong

The chain in total may be longer, but the timing is still correct.
This is due to the fact that the individual links in the chain still slide into/onto the teeth of the sprocket in precicesly the same sequence as they did when the chain was shorter. (only with added rattle)

Only when the chain becomes so loose that the gaps and the teeth won't match up anymore will your timing go out (or rather the chain will break a tooth off, the chain will tear or jump off the sprocket)

PS: ... and I was trying to be pedantic

Glad to see you've come on board!!

Slidey

unkel wrote: »

Whoah, hold on now you dudes are going too fast for me. Ok, so when a chain skips a tooth, on a modern engine that's bad. I got that. But does the chain not start rattling way before that, giving you the signal it's on the way out?

That has always been the reason I considered the chain superior to the belt. You don't have to worry about anything / know about anything. I mean a FIAT petrol needs a new belt every 30k miles / 4 years or something? 10 years and 100k miles on the Focus sounds decent but what if it snaps after 99k miles without warning?

Yeah, the chain will be clattering long long before it jumps the tooth.

TBH, there is no way in hell I would leave a belt 10 yrs or 100k miles. I don't give a shyte what the manufacturer has said. He will do some laughing at you if you come back with an 8 yr old car and a flittered timing belt!

beachlife

unkel wrote: »

Whoah, hold on now you dudes are going too fast for me. Ok, so when a chain skips a tooth, on a modern engine that's bad. I got that. But does the chain not start rattling way before that, giving you the signal it's on the way out?

That has always been the reason I considered the chain superior to the belt. You don't have to worry about anything / know about anything. I mean a FIAT petrol needs a new belt every 30k miles / 4 years or something? 10 years and 100k miles on the Focus sounds decent but what if it snaps after 99k miles without warning?

If it's a modern car then yes you will have "issues" with it long before it breaks

peasant

beachlife wrote: »

Glad to see you've come on board!!

I may be over fourty, but I'm not completely calcified yet

beachlife

Slidey wrote: »

Yeah, the chain will be clattering long long before it jumps the tooth.

TBH, there is no way in hell I would leave a belt 10 yrs or 100k miles. I don't give a shyte what the manufacturer has said. He will do some laughing at you if you come back with an 8 yr old car and a flittered timing belt!

I've done quite a few at the recommended milage and although I thought it to be a bit of a stretch.I have to say when I changed them the belt looked surprisingly good!!!

beachlife

peasant wrote: »

I may be over fourty, but I'm not completely calcified yet

same as myself:D

Slidey

beachlife wrote: »

I've done quite a few at the recommended milage and although I thought it to be a bit of a stretch.I have to say when I changed them the belt looked surprisingly good!!!

Fair enough.

I know the 3L Trooper has a really long belt life, think it is something like 125k miles but the belt only runs the cam as far as I remember. The rest of the junk in that engine is off timing gears.

I have never seen or heard of one of these belts snapping but then again not many of those engines manage to get to that mileage!

unkel

beachlife wrote: »

I've done quite a few at the recommended milage and although I thought it to be a bit of a stretch.I have to say when I changed them the belt looked surprisingly good!!!

Then there is the mileage and time issue. The belt in my 928 is due to be replaced every 5 years or 45k miles. It was replaced 6k miles ago. But that was over 6 years ago. This car is not prone at all to the belt breaking from what I've come across, but suffice to say I would feel a lot more comfy if it had a chain

beachlife

Sorry Unkel, should have clarified. I have done a couple off ford focus where the cars were at the correct time and mileage I.e ten years and almost 100k
or eight years and 100k etc. so what I was getting at was on this engine at least the interval is quite good and the cost of replacement is not prohibitive.
Where as if you own an alerma ?!?!?!?

CJhaughey

Slidey wrote: »

Fair enough.

I know the 3L Trooper has a really long belt life, think it is something like 125k miles but the belt only runs the cam as far as I remember. The rest of the junk in that engine is off timing gears.

I have never seen or heard of one of these belts snapping but then again not many of those engines manage to get to that mileage!

The 1KZ-TE Toyota lump also has a gear driven cam, the timing belt only runs the fuel pump nothing else and yet it only has a 60k Mile interval.
All the ones I have changed were in perfect nick, the belt doesn't work that hard, yet the light comes on to change it.

alias no.9

beachlife wrote: »

Sorry Alias there is no catch up or reset. the tooth on the gear/sprocket simply meshes with the roller of the chain until such time that the tooth the hits a point on the roller that is over centre and jump forward(skips a tooth)or snaps (forces the chain away to sit on the tooth)the chain. the point I am making is that the timing on any modern car would be so far off at this stage that the car will not be running.

I'm talking on a very micro scale, as each roller climbs further and further up each successive tooth (tiny amounts each time I know), the contact angle between the roller and the tooth will change. It's analagous to a wedge getting thinner and thinner, eventially the tension of the chain should be able to pull the roller back down the wedge some little bit which would in effect advance the camshaft a little relative to the crankshaft. Anyway, the point of this is that the relationship between camshaft and crankshaft timing with a worn chain will have an additional noiseyness.
It's late in the night but I'll sketch something tomorrow to further explain what I'm talking about. Maybe I'm just taking this way too far.

L1011

unkel wrote: »

I mean a FIAT petrol needs a new belt every 30k miles / 4 years or something?

45k miles, 5 years is what Fiat now recommend from memory.

On the 8V petrols you could realistically wait till the damn thing snaps, non-interference engine. On the 16V engines, follow it religiously...

alias no.9

MYOB wrote: »

45k miles, 5 years is what Fiat now recommend from memory.

On the 8V petrols you could realistically wait till the damn thing snaps, non-interference engine. On the 16V engines, follow it religiously...

SOHC 8V non interference engines are the ultimate deployment of timing belts, simple to change without the complex routing and extra idlers of a DOHC and fail safe.

beachlife

the 16 valve engine in the punto uses the same belt!! but if it break's POP GOES THE WEASEL!!!:D

Slidey

The old Transit engine would break belts fairly regularly but throw in a few push rods (or straighten the old ones :P) and you'd be back on the road in no length!

unkel

MYOB wrote: »

On the 8V petrols you could realistically wait till the damn thing snaps, non-interference engine. On the 16V engines, follow it religiously...

Yeah interference or non-interference, that is the question.

My car is an '86 S2 Euro 928 with the 4.7 310BHP 16 valves engine (V8 so only 2 valves per cylinder). The early 16V 928s were all non-interference and the late '86 and newer 32V models are all interference.

My googling skills are pretty good and so is the advice from the lads up on rennlist. Still don't know for sure whether my engine is interference or not. The best advice I've had so far is that if you are not certain the engine is non-interference, your engine is interference

BTW I'd challenge anyone in finding the definite answer for me. Free money, drinks and holidays are on offer here*

* this might require ringing very, very expensive phone lines first

plasmaguy

Went to the garage today and was told the timing chain on my Nissan Almera is stretched and needs replacing. Cost of the job would approach 1000 euro since it's a Nissan Main dealer.

Funny thing is I have heard no rattling of the Timing Chain and the car drives fine. But I read on another forum that sometimes more recent Timing Chains don't rattle before they go and it's only on older versions you hear the rattling.

The car is only worth a grand. Should I just keep driving, hope for the best and at worst drive the car into the ground and get another one. Is it worth replacing the timing chain or how long can a car survive with a stretched chain?

The engine malfunction light is showing which was the first indication of a problem.

Plug

Drive her into Dail eireann! No serously even a cheap garage would cost you at least €500. Just drive it until it wont drive any more and get a new one.

ianobrien

I was flicking through an old car magazine recently (I'm not too sure if it was practical motorist) from the 1970's and they were showing how to fit the Abrath Timing Belt kit into a Fiat 127, which had a timing chain. One benefit was more accurate cam timing.......