why chain cam ?

Honest John Back Room » Motoring discussion
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Sun 25 Apr 2010 22:10
why chain cam ? - diddy1234

I just watched HJ's video review of the new Nissan Micra at a show i Thailand.

I did notice that almost all of the cars are going for chain cam now, Why ?

From memory back nearly 15 - 20 years ago cars were chain cam then went to belt cam now that far east cars are going back to chain cam, why ?

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Sun 25 Apr 2010 22:21
why chain cam ? - Rattle

Chains are noisier than belts and need a good quality supply of oil. Now that engine oils of improved a lot this is not so much of an issue.

There has been too many problems of belts snapping and chains should last longer BUT if they do need replacing it costs a lot more and it is even more important that a chain cam engine gets its frequent oil changes.

All my cars have had a chain and ironically my next car which will be brand new is belt driven. Thankfully the engine dosn't bend the valves if the belt snaps though.

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Sun 25 Apr 2010 22:29
why chain cam ? - corax

No cambelt to change means lower servicing costs, and improves reliability, as there are no tensioner pulley issues. The timing can be made to be more accurate, as the chain isn't disturbed through the engines life, and with new manufacturing technology, they can be made more precisely and are much more durable than they were.

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Sun 25 Apr 2010 23:39
why chain cam ? - bathtub tom

>>No cambelt to change means lower servicing costs, and improves reliability

Please google (other search engines are available) 'nissan almera cam chain problems'>

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Mon 26 Apr 2010 08:12
why chain cam ? - Manatee

Toothed belts can break or more usually strip the teeth without warning, especially when they are driving the water pump and it seizes as one of ours did. A chain and tensioner will not last forever, but if properly lubricated will quite possibly last the life of the car and will usually rattle (sometimes for years) before it breaks, so they don't need scheduled precautionary replacement.

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Mon 26 Apr 2010 11:03
why chain cam ? - mike hannon
As usual it's all down to quality or cut-price engineering. A properly designed and made engine with a cambelt will be completely reliable, as long as service schedules are adhered to. A few years ago, at the height of the cambelt failure scaremongering, some makes featured all the time. Some didn't. Speaks for itself. Search for the threads on here (if they still exist) and you'll see for yourself.
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Tue 27 Apr 2010 05:29
why chain cam ? - piston power

Chains can stretch usually past 100k but as said oil changes is the key to a engines long life and frequent.

The tensioner for the chain the oil gallery becomes blocked release pressure to tensioner chain rattles then stretches and can snap.

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Thu 29 Apr 2010 18:00
why chain cam ? - Group B

My Saab 9-3 diesel had done 162k miles when I sold it, and had no cam chain problems. I never heard any noise from it (not over the din of the rest of the engine anyway). On Saabs, petrol or diesel, the view was that the chain would start to get noisy as it wore out, so give you plenty of warning before failure.

Cam belts are a nuisance IMO; unnecessary service cost, and a cause for stress if you get near the end of the quoted lifespan! :o(

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Thu 29 Apr 2010 22:20
why chain cam ? - nb857

what's wrong with gear driven cams? Engines that have to work hard for a living have them. Is it only automotive engines that have cam drive problems?

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Thu 29 Apr 2010 23:31
why chain cam ? - DP

Gear drive system for cams are expensive, and a living nightmare if ever you have to skim the cylinder head. They always strike me as overkill given that well designed belts and chains cause so few problems in reality.

Well designed belt drives last for six figure mileages, and are no significant contributor to overall running costs. These designs will only inflict one or two belt changes on owners over the entire working life of the vehicle. Chicken feed compared with fuel and other maintenance / consumable costs.

What confuses me is when engine designers use both belt and chain together. The 1.8T VAG engine in my Golf uses a belt to drive the exhaust cam, and then a short chain to drive the inlet cam off the exhaust cam. I cannot see why, from an engineering viewpoint, you would use both systems.

Edited by DP on 29/04/2010 at 23:33

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Sat 1 May 2010 16:33
why chain cam ? - SteveLee

What confuses me is when engine designers use both belt and chain together. The 1.8T VAG engine in my Golf uses a belt to drive the exhaust cam, and then a short chain to drive the inlet cam off the exhaust cam. I cannot see why, from an engineering viewpoint, you would use both systems.

Perhaps they wanted to release space on one side of the cylinder head to bolt things to? Hence internalising the drive to the second camshaft? I presume it simplifies the run of the cam belt too.

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