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[Field Marshal Dr. Opti]

Why do manufacturers use a cambelt, which requires costly periodic replacement, when a camchain will last the life of the car?

Is it for reasons of noise?

[ronnyd]

Probably the chain option is more expensive to manufacture and, as always, it,s down to costs.

[05omegav6]

Belts are quieter... makes the engine sound a bit more refined...

Chains could also be considered a service item, they stretch over time, but generally only fail completely if basic, regular oil changes are neglected

[Field Marshal Dr. Opti]

When it's time to change the cambelt......I prefer a chain.

[Bigron]

Reaching back into the depths of my memory, the BMC A-Series engine as fitted to my Autin A30 (and the Morris Minor?) had a brilliant timing chain arrangement whereby the chain was lubricated via the centre of a wear-adjusting neoprene-faced slipper, meaning that it was always under the correct tension and well lubricated. That was courtesy of Reynolds, the chain people, I think?
If they could get it SO right back then, what is their excuse now? Apart from being cheaper to make and assuring them of a regular service income.........

Ron.

[SteveAvfc.]

Owned a 2.2 Vectra once upon a time and the chained snapped on a trip back from Brum. Called out the recovery services where the not so clever man told me my cambelt had snapped  Maybe he was new to the job pleb!!.

[Magwheels]

The Rover (Buick) v8 was best, chain, no tensioner, never rattled and never failed in normal use.

[aaronjb]

The Rover (Buick) v8 was best, chain, no tensioner, never rattled and never failed in normal use.

Mr DTM will be along in a moment to tell you that every single Rover engine chain has stretched, the timing is out on every engine he's ever seen and they're all firing on less than all 8.. I'm sure that was his opinion of the RV8 last time I saw it mentioned, anyway

[Webby the Bear]

More to the point why are there not more 'safe' engines so that if the belt does go there's no meeting of valves and pistons?

[4x4]

A, if chains were used instead of belts stealers would lose money.
B,safe engines again,why be safe when everything bends when belt snaps,they are designed to be more expensive to repair,again keeps stealers happy 

[aaronjb]

More to the point why are there not more 'safe' engines so that if the belt does go there's no meeting of valves and pistons?

Because you don't get efficiency by building in safety - non interference would mean low compression or inefficient combustion chambers with heavily pocketed pistons etc, and modern engines are pretty much on the ragged edge of what the designers can get away with in the name of fuel economy and saving the environment..

[dbug]

Massive duplex chain on TR4A engine with tensioner good for 100K - when I rebuilt my TR4A engine original tensioner had done 90K and showed hardly any wear, but was replaced with new.

[Webby the Bear]

More to the point why are there not more 'safe' engines so that if the belt does go there's no meeting of valves and pistons?

Because you don't get efficiency by building in safety - non interference would mean low compression or inefficient combustion chambers with heavily pocketed pistons etc, and modern engines are pretty much on the ragged edge of what the designers can get away with in the name of fuel economy and saving the environment..

That's a good explanation Aaron.

I wonder though if the fiat panda can do it why aren't they like that on engines where performance is poor to average like most small cars.

[BazaJT]

Think belts were done for quieter operation-possibly weight saving too?-always preferred a cam chain set up myself,although early Jaguar V8s suffered from chain tensioner problems later cured at introduction of 4.2L engine.

[Webby the Bear]

. . . Plus of course the cost savings and revenue from repairs as Martin pointed out 

[The Sheriff]

More to the point why are there not more 'safe' engines so that if the belt does go there's no meeting of valves and pistons?

Long ago in the mists of time, I asked Mr DTM this very question. Interference engine v non-interference. He explained the answer in great detail. Wish I could remember........


It was something to do with power and efficiency.

Edit: i must read all posts before replying. Sorry Aaron.

[Field Marshal Dr. Opti]

More to the point why are there not more 'safe' engines so that if the belt does go there's no meeting of valves and pistons?

Because you don't get efficiency by building in safety - non interference would mean low compression or inefficient combustion chambers with heavily pocketed pistons etc, and modern engines are pretty much on the ragged edge of what the designers can get away with in the name of fuel economy and saving the environment..

Is this why my 1974 Capri 1600 OHC survived cambelt failure?

Truth be known it was a bit of a lorry.

[Andy B]

More to the point why are there not more 'safe' engines so that if the belt does go there's no meeting of valves and pistons?

Because you don't get efficiency by building in safety - non interference would mean low compression or inefficient combustion chambers with heavily pocketed pistons etc, and modern engines are pretty much on the ragged edge of what the designers can get away with in the name of fuel economy and saving the environment..

Is this why my 1974 Capri 1600 OHC survived cambelt failure?

Truth be known it was a bit of a lorry.

Yes. The Pinto engine was a safe engine.

[BazaJT]

Thought the 1600 OHC-presume you mean the pinto motor?-was an interference type and would survive depending on how hard engine was trying at time of failure and/or how lucky you were.

[Nick W]

Is this why my 1974 Capri 1600 OHC survived cambelt failure?

Yes. The Pinto engine was a safe engine.

2.0l Pintos are safe; I've refitted belts at the side of the road.  1.6l aren't, due to differences in the cylinderhead and valve lengths, although you might get away with it. You can bolt a 1.6l head onto a 2.0l engine but it won't run. I'm sure you can guess how I discovered that.


As for chain or belt, there are good and bad of both. Modern chains tend to be more problematic than older ones for a number of reasons: they're much longer; they tend to be noticably smaller; they are much more highly stressed compared to the short chains in OHV engines; oil change intervals are much longer, and the tensioners really don't appreciate that. But there are some bad chain installations: Mini(etc) A-series engines use a rubber coated flap to tension the belt, and slack/noisy chains are a common problem as a result; Micra engines and 2.0l diesel BMW engines are well-known for expensive chain issues(largely due to someone fitting it at the back of the engine). Good ones are excellent though, a robust chain with a heavyduty tensioner will last the life of the engine even on DOHCs; check out the cam chain rattle on an XK, Merc I6 or Rootes 4. You will need good hearing!

[Andy B]

2.0l Pintos are safe; I've refitted belts at the side of the road.  1.6l aren't, ....

It was a very long time ago now but I wound the crank round on my 1600 with the cam & followers fitted. Nothing fouled

[Magwheels]

Bring on electric power......None of the above to worry about......just whether you will have enough juice to get there!

Or back!

[Field Marshal Dr. Opti]

Hydrogen fuel cell is the way to go.

Once teleportation is invented we won't need to worry about the price of fuel.

[TheBoy]

Belts don't stretch, chains do. Doesn't matter how good a tensioner is, the valve timing will be out.

[The Sheriff]

Hydrogen fuel cell is the way to go.

Once teleportation is invented we won't need to worry about the price of fuel.

No, but British teleportation will charge a fortune for their services. Nothing ever changes, Opti.

[dbug]

Belts don't stretch, chains do. Doesn't matter how good a tensioner is, the valve timing will be out.

You sure - elastomer based

[Vamps]

Well the Honda is a chain, apparently.............

[05omegav6]

Belts don't stretch, chains do. Doesn't matter how good a tensioner is, the valve timing will be out.

You sure - elastomer based

Chains 'stretch' as a side effect of wear, belts are effectively stretched by the tensioner

[Marks DTM Calib]

The Rover (Buick) v8 was best, chain, no tensioner, never rattled and never failed in normal use.

Er, it never failed but, stretched badly and wore the gears so the cam timing goes a mile out. Hence why you can by beefed up replacement duplex chain sets for them.

Things to consider

1) Modern engines are not simple push rod units with the single cam close to the crank

2) Chains do stretch (despite oil changes etc)

3) Chain guides do wear (also despite oil changes)

4) Adjuster oil feeds can clog (as many are pressurised like a cam follower).

So my personal preference is a cam belt and workings, this is due to me keeping cars for high mileage and I am quit happy to change a belt and know its done and good, chains fail, that's a fact and they can be an absolute shit to change (ask a BMW 2.0 diesel driver......)

[Marks DTM Calib]

Belts don't stretch, chains do. Doesn't matter how good a tensioner is, the valve timing will be out.

You sure - elastomer based

No they don't generally as they might well be a rubber external coat but inside they have a Kevlar or nylon re-enforcing

[Doctor Gollum]

Seen a jag (the shite Mondeo one) v6 engine in for cam chain failure. Hideously complex chain routing. 3 differant chains iirc. Plastic chain guides. Worn chains resulting in stretch and poor running. Then ultimately chain failure where the U link had worn through. Clearly a softer link than the rest of the chain.

Iirc it had done 60k.

Bill? It was up over 1k and counting at the time.


Belts don't wear and stretch, but do perish and let the cords escape . But not until more than double the service life of the tensioner on omegas.




Interference engines are a result of higher compression to give better performance.

[Kevin Wood]

Belt every time for me, unless it's a stupidly simple arrangement such as on a pushrod engine. You're going to have to accept a shedload of slop in the timing then, anyway.

Yes, you have to maintain a belt, but that's a non-issue for me, even with the relatively short interval on the Omega, and at least you can get to it.

[05omegav6]

Belt every time for me, unless it's a stupidly simple arrangement such as on a pushrod engine. You're going to have to accept a shedload of slop in the timing then, anyway.

Yes, you have to maintain a belt, but that's a non-issue for me, even with the relatively short interval on the Omega, and at least you can get to it.

VW v6/v8/v10 anyone... 

[Kevin Wood]

VW v6/v8/v10 anyone... 

No Thanks.

[05omegav6]

 

[henryd]

Belt every time for me, unless it's a stupidly simple arrangement such as on a pushrod engine. You're going to have to accept a shedload of slop in the timing then, anyway.

Yes, you have to maintain a belt, but that's a non-issue for me, even with the relatively short interval on the Omega, and at least you can get to it.

VW v6/v8/v10 anyone... 

My Vw 5 banger is gear driven,actually so are water pump,a/c ,alternator and pas pumps,we don't need that lot going wrong

[78bex]

So why not run the cam drive belt into the sump oil for more efficency 

https://www.youtube.com/watch?v=IFj5UIZx2cE

[chrisgixer]

Nah. Makes access more tricky. Like the Ford give crap about that.

[Marks DTM Calib]

Belt every time for me, unless it's a stupidly simple arrangement such as on a pushrod engine. You're going to have to accept a shedload of slop in the timing then, anyway.

Yes, you have to maintain a belt, but that's a non-issue for me, even with the relatively short interval on the Omega, and at least you can get to it.

VW v6/v8/v10 anyone... 

My Vw 5 banger is gear driven, actually so are water pump, a/c ,alternator and pas pumps, we don't need that lot going wrong

Gear driven....chatter chatter chatter.....or if they have the spring loaded compensator gear set nice and quiet......until they age and then chatter chatter chatter 

[henryd]

Belt every time for me, unless it's a stupidly simple arrangement such as on a pushrod engine. You're going to have to accept a shedload of slop in the timing then, anyway.

Yes, you have to maintain a belt, but that's a non-issue for me, even with the relatively short interval on the Omega, and at least you can get to it.

VW v6/v8/v10 anyone... 

My Vw 5 banger is gear driven, actually so are water pump, a/c ,alternator and pas pumps, we don't need that lot going wrong

Gear driven....chatter chatter chatter.....or if they have the spring loaded compensator gear set nice and quiet......until they age and then chatter chatter chatter 

Yes,a little at cold idle but very quiet once revving(for an oiler)