Chatted with an AA mechanic the other day: his pet gripe was about car salesmen who make great selling points about cars having camshafts driven by chain rather than belt. The mechanic said many modern cars have very flimsy chains compared with those of cars from yonder days of yore, and need replacing just as often as belts. And if they break the damage can be just as catastrophic. When we bought our NZ-new 1999 Accord in 2009 at 64000 km we replaced the belt ("100000 km or 5 years" the handbook said), tensioner and water pump. Our mechanic said the belt was in perfect condition but if the car had spent much of its life idling in Tokyo traffic it could have been another story, and the new parts should be good for 100000 km. Chain drives on our old cars; the 1964 BMC 1100's one was beginning to rattle a little at 130000 miles so I replaced that, and the one on our 1970 Triumph 2000 I replaced as a matter of course at 199000 miles when the engine received rings and bearings, crankshaft thrust washers and a top overhaul, although it showed little wear. I wonder if "they don't make them like they used to?" (I realise that modern engines can have twice as many valves for the shafts to operate, but should they not have much beefier chains?)
snoopy221,
Aug 20, 1:41pm
Reality back in those days they had points and carburetors and gobbled fuel. mechanics back in those days that had them on a tunescope KNEW all about the massive timing variations. Then cam belts and electronic ignition and the resultant better fuel economy. Then came fuel injection and even better economy. Sadly people did not maintain them and the horror stories of belts breaking had the older gents saying a chain was better, Alas a chain with modern ignition and fuel injection and a computer mean camshaft and crankshaft sensors and they have a hissy fit when the chain is worn. As to breakages well again with better fuel and ignition control and sequential turbos the stresses show that the engine outlives the chain. Yip personally i prefer an easy changeable belt.
bwg11,
Aug 20, 2:19pm
Certainly the BMC A Series did get rattly a low mileages as #1 suggests, but chains were cheap as chips, and you could replace a chain in half an hour on the north south variants, a bit longer on the transverse FWD versions.
kazbanz,
Aug 20, 2:48pm
IMO the mechanic is on the whole talking rubbish. For a starter I haven't personally heard of a modern car cam chain actually breaking. -actually correction--Not in an unmodified normally stressed engine.-race engines are a different story. Stretch yes--its common knowledge that Holden and VW both had quality control issues with one generation of chains but not actual breakage.(different times same issue) On the whole camchains nowadays are lasting several hundred thousand K's with no issues so flimsy wouldn't be my description.
snoopy221,
Aug 20, 3:10pm
Yeah but ya avoid zeee old euros liken zee ! hitlers revenge! kaz And as much as some on here espouse them zey are reknown for zee chain failures.
The only car i know that had problems with a chain was a workmate with a hillman avenger whose chain was so loose it "jumped of the sprockets on the motorway. Minor 1000,s got a bit rattley but the B series(oxfords etc ) had a duplex chain rather than the single chain and didnt give any problems.I,m sure someone on here has a different opinion but.
flack88,
Aug 20, 5:05pm
The cam chain in some later model BMW like a bike chain from the wharehouse utter junk.
richardmayes,
Aug 20, 5:27pm
For structures like suspension bridges where a failure of the main tension member would be truly catastrophic, a multi-strand cable is used that has hundreds if not thousands of parallel wires. If one strand out of 1,000 fails, the capacity of the cable is only reduced to 99.9%.
If you have a chain with 1,000 links doing the same job, a failure of one link reduces the capacity of the chain to 0.00%. Hence all of the folklore about a chain being only as strong as its weakest link.
I don't know anything about how timing belts are constructed, but I imagine there is a lot more to them than the black rubber that meets the eye! on the old vee shaped fan belts you can usually see a fabric backing material that is made up of a large number of parallel, load-sharing fibres.
kazbanz,
Aug 20, 6:24pm
Richard--all that is well and good But as a rule the way a cambelt fails isn't "that " way Its a failure of the teeth not so much the belt itself. So "kinda" it is the black rubber bit you see that's the issue. A chain on the other hand will generally stretch to the point its rattling away inside the tunnel by then all the engine check lights are on and likely the cam/crank angle sensors are fritzed.
mals69,
Aug 20, 6:29pm
Go gear driven and avoid being a member of the shag around club .
snoopy221,
Aug 20, 6:31pm
True dat still the same old same old. No technological advances in tensioners causing failure-LOL
gazzat22,
Aug 20, 9:17pm
On a slightly different tack my friend has been a mechanic for 40 year +.Before he went into business himself he was a Foreman at a garage that was contracted to the AA for towing and repairs.He always said the only people who worked for the AA were people that couldnt get a job as a mechanic anywhere else.
wind.turbine,
Aug 21, 6:38am
my triton is over the ridge and heading towards 300k, no sign of chain rattle. think a big part is owners keeping them serviced on time
in saying that though I have heard that if the chain starts to rattle all of a sudden, its the top guide and it needs replacing right away to avoid the chain jumping
the-lada-dude,
Aug 21, 7:56am
Tell that to MK 4 Ford Zephyr owners . and didn't GM sixes have a problem at one stage
friendly_prawn,
Aug 21, 8:04am
I have owned and driven far more cars than the average person in here, (car dealers aside) and I have never in my life had a problem with the chain system. Im my humble opinion they are the ultimate. The real problem with cambelt's aside from the obvious they are expensive to replace and need replacing on average every 100,000k's. they are also a major issue when buying a car and there is no history of the cambelt being replaced. Do you do an expensive belt, tensioner etc, replacement just incase? Or do you just keep driving it and keep your fingers crossed.
I would be buying a car that was chain driven every single time if I had the choice. Cambelt's are a pain in the ass.
martin11,
Aug 21, 8:09am
Had a Jaguar break its chain a few years ago did a lot of damage to the covers and gears . It does happen . Also heard of an Audi not so long ago that also broke .
thejazzpianoma,
Aug 21, 8:50am
Car dealers love chain driven cars because they don't have to foot the bill for a timing belt before sale or alternatively explain that expensive maintenance is due.
Most of the stuff they choose to import is low enough km to get them out of their obligation under the CGA before chain stretch or breakage occurs.
The other factor is they will say anything to make a car sound good. When what they sell doesn't drive as nice, isn't galvanised, lacks features etc compared to what else is available. Suddenly everything not made in Japan is unreliable. That's another classic example.
On here they just deny serious issues even exist, if anyone brings them up they use the power of numbers to shut them down very quickly.
You see this time and again with the likes of short life Tiida transmissions, Toyota 2.4 liters that burn oil etc.
kazbanz,
Aug 21, 9:13am
Fairy nuff martin. Can't argue with real world personal experience. -What year was the Jag?--ie was it a Jag or one of those ford/jags Are you sure the Audi was chain though?-Given audi product up to the mid 2000's were still using belts.
morrisman1,
Aug 21, 9:29am
Timing chains became a selling point due to some cars being quite expensive to do the timing belt on. which system is better really comes down more to individual models than a generalisation. There are some cars out there that break belts really easily and must be changed when scheduled, there are also cars out there that have reputations for stretching timing chains. In general timing chains are cheaper to own, and if you do the required oil changes then they seldom ever need replaced.
I don't think anyone has ever denied that the 2.4 Toyota can be an oil burner. Its a widely recognized issue. The Tiida transmissions on the other hand. I've only ever heard of one person who claims they fail. But on the related issue, the Tiida has a silent timing chain which appears to be a rock solid and reliable design.
Silent timing chains have a different tooth profile, and instead of being like a bike chain in design, can be better described more like a steel timing belt
martin11,
Aug 21, 9:34am
MK2 Jag and the Audi I believe was a late model one will check .
Jaguar XJ6 (3 chains to drive the camshafts on these!): Lady at work bought a 1986 Series III back in the 1990s when they sold for about $30000. Noticed her topping up the radiator one day before driving home. Said it took about 1/2 litre every day. Suggested she check everywhere for leaks when it was warmed up, and that "worst case scenario" could be cylinder head gasket failure. Sure enough, that was what it was, and it was repaired under warranty by the dealer from whom she bought the car. Sometime later I was chatting to her, the engine was idling and when I rested my hand on the roof I could feel vibration. She said it hadn't been running well since the gasket repair and garage hadn't found the cause. I wondered whether one of the camshafts had not been lined up correctly. Sure enough, one was 1 tooth out of sync. that fixed and all was well!
snoopy221,
Aug 21, 9:58am
From jmma"s link in post#23
The real problem here is that this will usually occur when you have turned your engine off. The next time you start your vehicle all symptoms are present for the timing chain to jump out of time as you crank the engine over to start it.
Yip- had one jump 3 teeth no internal damage-and first thing was damn check the video at the gas station. As yip as sure as eggs it had just been fueled and instantly ran like the proverbial hairy goat-LOL
kazbanz,
Aug 21, 11:18am
So a systemic proven failure of VAG group engines.
mals69,
Aug 21, 4:12pm
Doubt OP buying a MK4 grenade or a dated gm six.
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