Changing Cam Sprockets

[Tanz]

While I'm sorting the Power steering (see other post) I decided to change the long overdue cam belt. The belt was last changed by Lotus bits when they did my exhaust and clutch. At the time, Dave said the cams looked very worn and should be changed at the next cam belt change. So I am changing them now and also the crack sprocket. The distributer sprocket looks OK to me - Guess it is easier to turn so wears less? The edges of the 'teeth' appear much sharper on the old spockets




Had to make a puller tool to get the Crank sprocket off


This is what my engine bay looks like at the moment!!


Hoping to put it all back together next weekend weather permitting

[Hawaiis0]

Wow - that looks a huge amount of wear. What's your mileage for the record?

[Tanz]

Wow - that looks a huge amount of wear. What's your mileage for the record?

I think about 110,000 the last time I looked.
I don’t think it is unusual for the crank sprocket to wear. I seem to remember Angus having some issues a few years ago unless I imagined it.

[Bigvolvo]

Yes, freaky amount of wear. These spockets would surely be case hardened- the cambelts must be abrasive. They have kevlar in them dont they?

[amarshall]

Wow - that looks a huge amount of wear. What's your mileage for the record?

I think about 110,000 the last time I looked.
I don’t think it is unusual for the crack sprocket to wear. I seem to remember Angus having some issues a few years ago unless I imagined it.

Indeed - just around 100k miles too. It was so bad that a new belt was all but destroyed within a few hundred miles. Still haven't worked out if it was normal wear or a tensioning problem or a combination of the two.

The first indication that I had of the problem was a "chuffing" sound at idle from the damaged area of the belt.

[Bigvolvo]

having read up a little it seems the belts do contain Kevlar. Rounded tooth belts are thought to cause less tooth wear than the older square type. I wonder if occasional lubrication with something like graphite powder would lessen wear? So long as it doesnt degrade the belt.
On a separate note; how long will it be before there are engines without belts, chains, cogs or indeed cams? Perhaps the valves can be piezo electrically operated!?

[amarshall]

On a separate note; how long will it be before there are engines without belts, chains, cogs or indeed cams? Perhaps the valves can be piezo electrically operated!?

They already exist in various engineering facilities, including one in Norfolk: http://www.parostech.co.uk/camless.htm

Renault have also tried a hydraulic system : http://scarbsf1.com/valves.html