|
Been wondering for a while - if timing belts are so troublesome and the cause of catastrophic engine failures why do manufacturers use them at all over timing chains?
|
|
cost?
|
As my postings would indicate I've had a bad experience with these belts (or rather the tensioners/idlers).
It may be that they are cheaper than chains, perhaps quieter, but it's hard to avoid the conclusion that some makes simply produce a more reliable cambelt arrangement than others.
To get some idea of the frequency and sources of such problems you might like to search on Google newsgroup: uk . rec . cars . maintenance
|
|
|
|
|
and less noisy!
|
Gear drive good.
Vertical shaft with bevels good.
Triple eccentrics with connecting rods good. Double eccentrics work, need balancing. Both silent.
Sleeve valves brilliant.
Side valves crude but safe
Chain can be good.
Belts cheap modern rubbish.
|
|
|
|
|
As the others have said, noise and cost, and in theory lower maintenance. No hydraulic tensioner, no oil sealing problems. But don't forget, chains can give problems as well. A lot of people never have any problems with belts.
|
As well as reasons of cost, noise and efficiency (less weight), belts give the dealer an opportunity to charge for something at 36k service!!!
|
|
|
|
|
If chains are nosier why do BMW fit them ? Wish my A4 had one like my previous two Primeras.
|
|
In just a few years time, with the rapid advances in electronics, we will probably look back and think how antiquated it all was. My bet is that valves will be operated via electronics & solenoids
|
Or, a hydraulic pump on the crankshaft, and a hydraulic motor on the camshaft with total synchronisation via some software.
Or, an electric motor on the camshaft etc, etc.
|
|
|
|
Pete,
You mentioned before that you took a big hit when you changed your Primera (as you do). Was it beginning to annoy you, or did you just feel it was time to move on?
I've put in synthetic gearbox oil, too (Amsoil). Only helped a little, though.
Was yours a "tool eater"? Mine's a 1.6.
To get back on topic, it says in the *car by car breakdown* that (to paraphrase) "one chain good, two chains bad". But I would have thought that two short ones might theoretically be better than one longer simplex chain.
Bono
|
I had the 2 litre (one chain i believe) the correct power for the weight of the car
The latest primera at that time was another 3" longer so wouldn't fit the garage
and the interiors had really dropped in standard , a long with the fact that i wanted more power and four wheel drive but not a off road lorry prompted a risk change to vw group , been reliable so far except for a head lamp bulb after only 18 months (ten years with nissan never changed a bulb)
|
Thanks for indulging a Nissan fan, Pete.
I can see where you're coming from; I bet you never got excited at the prospect of getting into your Nissan at the end of a day's graft.
Bono
|
|
|
|
|
|
Apparantly Lotus already have a prototype petrol engine where the valves are operated by software and there is no spark plug .... no it wasn't April 1st.
|
|
|
|
Whether one uses belts, chains, hydraulics or electronics to open the valves even the most efficient of these willl still only be the best of a bad lot. The problem will remain that when the piston at TDC overlaps the open valves failure of any of these systemswill result in disaster for the car owner. Surely it would not be difficult to design a rotary valve which operates with the same efficiency as the poppet valve and eliminates the problem entirely?
|
|
|
Many manufacturers are going back to chains. A huge advantage of the S-4D engine in Spud's new Yaris is it has a chain driven camshaft, like all other Yaris models. Even Toyota is now gradually moving to chains. So is GM Opel Vauxhall which started the whole belt cam thing with the Victor 101.
HJ
|
Vauxhall 101, was this the late 60's?
I know there was a rally Ford Escort T/CAM with a BDA (belt driven assembly) in 1968.
|
It was the Victor FD I think, the successor to the 101, which first brought OHC to the mass market. The change to a cambelt coincided with this move.
as well as the advanced new engines, the FD and FE were good looking cars, and I remember driving around for a day with a rep who enthused all day about his new tool. They still look good today, or would if you could find one that hasn't rusted, which you won't.
|
|
|
|
The new MINI has a chain cam, just like the old one did, except that in the case of the new MINI thre cams are in the right place.
HJ
|
|
|
|
Can someone answer Tom Shaws point! I'd love to know!
|
|
|
