Timing Belt vs Timing Chain.

Matt406

Sorry if this is a stupid question but what’s the difference between a timing belt and timing chain? Does a timing chain need to be replaced the same as a timing belt? Thanks.

colm_mcm

chains don't snap or perish.
If a chain is on the way out it'll rattle for ages beforehand, belts just snap without warning.
Chains often don't have a set interval for changing.

jimmyw

A timing belt/chain is the link between the crankshaft and camshaft. The belt must be changed at certain intervals but a chain does not.

cormie

Ignore this :P

peasant

Not quite correct, even a chain lenghtens and will have to be replaced eventually ...but it usually advertises that fact quite well through an audible rattle.

bbbbb

Is it correct to say the only advantage of a belt is cost? (for the manufacturer)

colm_mcm

Yep, that'd be fair to say. that and the fact that many engines are developents of older engines which used belts.

FREE D DAN

chain has to be running in oil more seals more complicated........... belt is less hassle it runs outside engine

unkel

bbbbb wrote: »

Is it correct to say the only advantage of a belt is cost? (for the manufacturer)

And the recurring big bills for the belt changes (for the manufacturer and his agents)

And the even bigger bills for engine changes after belts snap, prematurely or not (for the manufacturer and his agents)

Another benefit of the belt is that it is quieter, but that's only noticeable in cheaper cars (i.e. I can't hear the chain on my BMW 5-series or 7-series from within the car)

alias no.9

bbbbb wrote: »

Is it correct to say the only advantage of a belt is cost? (for the manufacturer)

Not quite the full story
- belts do not stretch
- they are generally quieter
- on SOHC engines where they originated, they were cheap and easy to change and usually fail safe on 8v engines
The workload on a timing belt on a modern DOHC engine with variable valve timing is much greater than it was on early SOHC engines. Changing the belts and setting the timing is more comlex, driving up labour costs. Idler pulleys and tensioners have become quite expensive driving up parts costs.

JHMEG

Higher revving engines tended to have belts because of their lower mass.

dmca77

If a chain driven engine does not have a full service history. DO NOT TOUCH. Chain is lubricated by the oil and in turn if not changed regulary the oil eats away at the chain!

CJhaughey

dmca77 wrote: »

If a chain driven engine does not have a full service history. DO NOT TOUCH. Chain is lubricated by the oil and in turn if not changed regulary the oil eats away at the chain!

How can oil eat away at a chain? Unless it was more acid than oil and in that case your engine would have dissolved at the head before then.
:rolleyes:
Chains are made of steel, cyl head are made of alloy, which will be eaten away first?
If the oil had enough swarf to destroy a chain what would the pistons look like?

dmca77

CJhaughey wrote: »

How can oil eat away at a chain? Unless it was more acid than oil and in that case your engine would have dissolved at the head before then.
:rolleyes:
Chains are made of steel, cyl head are made of alloy, which will be eaten away first?
If the oil had enough swarf to destroy a chain what would the pistons look like?

You go to any manufacturer with a chain problem first thing you are asked does the vehicle have a service history. the longer you go without an oil change the more strain it puts on your timing chain thats because the oil gets thicker .......... hence why it stretches

dmca77

CJhaughey wrote: »

How can oil eat away at a chain? Unless it was more acid than oil and in that case your engine would have dissolved at the head before then.
:rolleyes:
Chains are made of steel, cyl head are made of alloy, which will be eaten away first?
If the oil had enough swarf to destroy a chain what would the pistons look like?

Ill never leave my car in you hands, are all cyl heads made off alloy?

kyote00

Is it not as straight forward as that.

Most Manufacturers are only indirectly related to the forecourts. The forecourt garages (sales) are involved mainly in sales. The sales and service are often independant legal and accounting entities in Ireland.

So.....

Belts which need to be changed very often only provided minumum revenue to the manufacturer and lots of revenue (via labour) to the service units of the garages.....

bbbbb wrote: »

Is it correct to say the only advantage of a belt is cost? (for the manufacturer)

Fishtits

Timing belts were dreamed up by some sod with too much time on their hands...:D

Chains, properly designed & specced, coupled with regular oil changes etc will last the life of an engine. (there are examples out there where they got it wrong however... pssst Almera)

ie - give me an example where a manufacturer states a change mileage for a chain?

Belts are nasty IMHO (herselfs' TDI is due a change so I may be biased )

CJhaughey

dmca77 wrote: »

You go to any manufacturer with a chain problem first thing you are asked does the vehicle have a service history. the longer you go without an oil change the more strain it puts on your timing chain thats because the oil gets thicker .......... hence why it stretches

Honestly thicker oil stretches chains? :rolleyes:
Of course any manufacturer will ask if you have a service history, if you don't it makes life a lot simpler for them.
I will let you in on a secret, chains don't stretch, they wear.

peasant

Fishtits wrote: »

Timing belts were dreamed up by some sod with too much time on their hands...:D

Rumour has it that they were dreamed up (for cars) by Hans Glas after he'd fixed his mother's kitchen mixer which was driven by just such a belt.

Anyhow, the Glas 1004

was the first ever car to have a timing belt.

The engine on that car was designed by ex BMW designer Leonhard Ischinger ...so you can either blame Hans Glas or Herr Ischinger ... but the Germans, at any rate

dmca77

CJhaughey wrote: »

Honestly thicker oil stretches chains? :rolleyes:
Of course any manufacturer will ask if you have a service history, if you don't it makes life a lot simpler for them.
I will let you in on a secret, chains don't stretch, they wear.

So they wear away then and not stretch? Worked on many have you?
Where is my answer for alloy heads? Still waiting!!
If you don't have a clue don't get involved.

D

dmca77

CJhaughey wrote: »

Honestly thicker oil stretches chains? :rolleyes:
Of course any manufacturer will ask if you have a service history, if you don't it makes life a lot simpler for them.
I will let you in on a secret, chains don't stretch, they wear.

God help the Irish Public if you work on there cars!!!!!

dmca77

CJhaughey wrote: »

Honestly thicker oil stretches chains? :rolleyes:
Of course any manufacturer will ask if you have a service history, if you don't it makes life a lot simpler for them.
I will let you in on a secret, chains don't stretch, they wear.

How many chains have you replaced??

alias no.9

Timing chains can and do stretch.
Failure to observe the oil change schedule will result in wear rather than any chemical attack.
Steel is in fact an alloy, but that's just being pedantic .

CJhaughey

dmca77 wrote: »

So they wear away then and not stretch? Worked on many have you?
Where is my answer for alloy heads? Still waiting!!
If you don't have a clue don't get involved.

D

Chains don't stretch and they do not get attacked by oil.
FFS they are not rubber bands.
Not all cyl heads are alloy but the majority are.
And yes FYI I have replaced plenty of chains in my time in both bike and car lumps.

Theshedog

alias no.9 wrote: »

Timing chains can and do stretch.
Failure to observe the oil change schedule will result in wear rather than any chemical attack.
Steel is in fact an alloy, but that's just being pedantic .

+1, I've changed a number of them before for this reason.

CJhaughey

alias no.9 wrote: »

Timing chains can and do stretch.
Failure to observe the oil change schedule will result in wear rather than any chemical attack.
Steel is in fact an alloy, but that's just being pedantic .

Chains don't stretch they wear out of tolerance, same with motorcycle drive chains they wear and get loose on the sprockets, they don't stretch.
Measure the side plates on a chain new and at replacement, is the side plate longer? answer is no it is not. The wear occurs in the pins and bushings.

Mycroft H

CJhaughey wrote: »

Honestly thicker oil stretches chains? :rolleyes:
Of course any manufacturer will ask if you have a service history, if you don't it makes life a lot simpler for them.
I will let you in on a secret, chains don't stretch, they wear.

:rolleyes:


You may eat humble pie


I've seen only one stretch (bearing in mind, im not a professional mechanic) but ive seen it with my own eyes, they can and do

Had the pleasure of trying to replace on in a merc 190 1.8 that was in rag order from the previous order with my uncle, a job that took quite a while

dmca77

CJhaughey

Out numbered my friend.

Hate when wrong are you.

And you are.. Timing chains do not wear they stretch...


bummer

Not changed many in car engines and inspected have we now!!!!!!!!!!

Mycroft H

dmca77 wrote: »

CJhaughey

Out numbered my friend.

Hate when wrong are you.

And you are.. Timing chains do not wear they stretch...


bummer

Not changed many in car engines and inspected have we now!!!!!!!!!!

You sir are the opposite as whats known as a sore loser. Get over it your right.

unkel

dmca77 wrote: »

You go to any the manufacturer of your Nissan Almera with a chain problem first thing you are asked does the vehicle have a service history

FYP

Slidey

Oh great, the max power mechanics have landed

Theshedog

CJhaughey wrote: »

Chains don't stretch they wear out of tolerance, same with motorcycle drive chains they wear and get loose on the sprockets, they don't stretch.
Measure the side plates on a chain new and at replacement, is the side plate longer? answer is no it is not. The wear occurs in the pins and bushings.

+1

A mistake alot of people make. The wear causes people to think the chain is streching.

"The effect of wear on a roller chain is to increase the spacing of the links, causing the chain to grow longer. Note that this is not from any actual stretching of any metal, as too many engineers and mechanics intuitively believe, but is due to the effect of wear at the pivoting parts. It could be said that the roller chain loosens with wear"

Check this out (I know its bicycle chains but same principle applies)

http://www.sheldonbrown.com/chains.html

Slidey

I will say this.

According to Mercedes if the high pressure fuel pump on the CDI engine locks up it can stretch the chain.

However, I have seen several of these lock solid and the chains were all perfect afterwards.

CJhaughey

Theshedog wrote: »

+1

A mistake alot of people make. The wear causes people to think the chain is streching.

"The effect of wear on a roller chain is to increase the spacing of the links, causing the chain to grow longer. Note that this is not from any actual stretching of any metal, as too many engineers and mechanics intuitively believe, but is due to the effect of wear at the pivoting parts. It could be said that the roller chain loosens with wear"

Check this out (I know its bicycle chains but same principle applies)

http://www.sheldonbrown.com/chains.html

Its the exact point I have been making for the last half hour.
Chains wear out of tolerance, commonly known as stretching, but they don't actually stretch, if they did the sideplates would elongate, the amount of force it would take to stretch a chains sideplate is far beyond what a camshaft or crankshaft could provide without pulling the engine to bits.
But you can't make people understand that seemingly.:D

Mycroft H

CJhaughey wrote: »

Its the exact point I have been making for the last half hour.
Chains wear out of tolerance, commonly known as stretching, but they don't actually stretch, if they did the sideplates would elongate, the amount of force it would take to stretch a chains sideplate is far beyond what a camshaft or crankshaft could provide without pulling the engine to bits.
But you can't make people understand that seemingly.:D

Ahh i see, so they do stretch?

vw4life

chains and belts shoud be checked and replaced according to manufacturers recommendations and I've replaced as many chains as I've done belts

congo_90

mindless arguing aside. Lets see some evidence.
First poster to change a chain and measure it between a set of rivets on it compared to the same amount on a new one will be the best answer to this stretching v's non stretching.

Imo chains wear out and eventually fail. I'm not saying they will but can.

Slidey

The problem with that is measuring between the exact centres is not going to very easy.

It could be very easy to be one side of the top of the rivet.

If I get a chance I will get someone to find me the specs for the Mercedes chain which they ask you to measure when the high pressure pump seizes

alias no.9

Theshedog wrote: »

+1

A mistake alot of people make. The wear causes people to think the chain is streching.

"The effect of wear on a roller chain is to increase the spacing of the links, causing the chain to grow longer. Note that this is not from any actual stretching of any metal, as too many engineers and mechanics intuitively believe, but is due to the effect of wear at the pivoting parts. It could be said that the roller chain loosens with wear"

Check this out (I know its bicycle chains but same principle applies)

http://www.sheldonbrown.com/chains.html

It's the fact that the chain has extended or stretched that means that it can no longer fulfil its function because the timing willl be out. If you take a worn chain, pull it to the point of tension, measure the length, it will be longer than it was when new. If the overall length of the chain assembly increases, it has stretched, regardless of where the extension has come from. It's the basic difference between parts and assemblies, tolerances stack up on assemblies.

vw4life

Slidey wrote: »

The problem with that is measuring between the exact centres is not going to very easy.

It could be very easy to be one side of the top of the rivet.

If I get a chance I will get someone to find me the specs for the Mercedes chain which they ask you to measure when the high pressure pump seizes

I'll get you a new chain and a worn one t'moro from a '03 E200 if you want

Slidey

alias no.9 wrote: »

If the overall length of the chain assembly increases, it has stretched, regardless of where the extension has come from.

Trying not to be pedantic here, but it has rather lengthened than stretched.

As already said, the reason it has gotten longer is because the pins and bushes have worn in the links.

If the links themselves have become elongated from their original shape, then IMO, it would be correct to say it had stretched.

peasant

alias no.9 wrote: »

It's the fact that the chain has extended or stretched that means that it can no longer fulfil its function because the timing willl be out.

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

vw4life

peasant wrote: »

Close ...but still wrong

The chain in total may be longer, but the timing is still correct.

not on any ones I've done,timing is always off,sometimes the eng. mil comes on and stores a camshaft position sensor fault because the timing is that far out

peasant

vw4life wrote: »

not on any ones I've done,timing is always off,sometimes the eng. mil comes on and stores a camshaft position sensor fault because the timing is that far out

Every day is a school day, or so it seems ...

Wouldn't have thought that that would be the case

maidhc

both chains and belts are imperfect.

Timing gears FTW.

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

Wrong!!!! The chain will be longer,why? because of the wear/stretch(what ever you want to call it,basically a "worn" chain IS longer than a new chain)and how will it be longer? the distance on each and every pin will be slightly longer so the camshaft/crankshaft WILL be off. Think if a camshaft has it's timing mark at 12 o'clock and the crank shaft has it's timing mark at 12 also and the tight side(no the tensioner side) of the chain has 80 links between them if the chain get's longer now when you have the same 80 links between them the marks won't line up.
I've seen it many times.OLd honda 50's used to be half a link out all the time and still run(badly)

Slidey

vw4life wrote: »

not on any ones I've done,timing is always off,sometimes the eng. mil comes on and stores a camshaft position sensor fault because the timing is that far out

Sorry P, I gotta side with vw4life.

If the pins are worn the chain will have gotten longer.

Now if the distance between pin a and pin b 25 links away is normally 200mm and all the links are worn then the distance will have increased.

The result of this is that the chain length between the crank pulley and the cam has increased and now the cam timing will be slightly retarded.

alias no.9

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

Yes, you're correct. It's late in the day, first day back in work after a long break.

beachlife

I also feel that newer car/bikes have less of a tolerance for mis-timing than the older machines.actually I know that they have her's the proof of worn/strected timing chain affecting timing.
Enjoy.

alias no.9

beachlife wrote: »

I also feel that newer car/bikes have less of a tolerance for mis-timing than the older machines.actually I know that they have her's the proof of worn/strected timing chain affecting timing.
Enjoy.

That's a good illustration of what's happening. A lot of us, me included, have been thinking about this one too simplistically, the system is limited both by the ratio of teeth on the sprockets as well as the length of the chain / pitch of the links.
On average, the crankshaft and camshaft have to stay in in synch, two revs of the crankshaft to every rev of the cam shaft until it skips a tooth which I think was Pesants point.
With a stretched/worn chain, you get a tooth by tooth retardation of the camshaft but as long as each link of the chain is mating with the correct tooth on each sprocket it will eventually be forced to catch up or reset after a given number of teeth in order for the chain to continue to mesh with the sprocket.
As the wear/stretching gets worse, the number of teeth between resets will increase in theroy until it would eventually skip a tooth.

beachlife

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.