I've just read about timing belts in meganes snapping and causing expensive damage to the engine. I'm concerned because i don't know if it has been changed or not since the car was manufactured. I asked the person who i bought the car from and they had never changed it. They bought it at 40k. The car has now done 82k. I looked at the timing belt and its looks new, but im not experienced in that. After reading about megane timing belts i'm going to get it done now, but does anyone know how much it will cost? Also i've got a tapping noise from the engine when its idling. Could this be caused by the timing belt or its tensioner? The last thing i want is this belt to snap as i've spent loads on this car already.
renault megane timing belt worry -
I agree with your statement that looks can be deceptive, but I would go further than that, to say that it is impossible to tell the condition of a cam belt by inspection in a workshop alone. One serious form of damage with any component of composite construction is hidden reinforcement fibre damage.
In a cambelt, it is these fibres which carry the tensile load, the rubber teeth are just to enable positive drive from the pulleys. The rubber backing is there to keep the reinforcement fibres on the neutral axis of the belt section in bending.
In the aerospace industry, composite components are routinely scanned using ultrasonics to detect this type of hidden fibre damage.
Of course, if you see any damage in the tooth roots when you flex the belt you should replace it. By this time, you are halfway to replacing the belt anyway, so for the extra cost of the belt, it would seem a false economy to refit it.
I've just bought a 1.4 Megane which had had a timing belt snap at around 73k - needed a top end rebuild costing £600. Not sure how much a simple belt change would be but it's gotta be cheaper than fixing the results of a broken one!
The tapping noise could be just tappets, I gather they are adjustable (i.e. not shims) on this engine, perhaps someone else could confirm?
Cost me about £120 for a simple belt change, about 18 months ago, from a local independant. Out of interest the same job for the awful 1.6 16v Vauxhall Ecotek cost me getting on for £300 for the same preventative job but including all the Vauxhall el cheapo plastic tensioners etc.
There are a number of prototype engines around with electronic valve control/actuation. Ford had prototypes 13 years ago. Some have the valve electronically actuated (e.g. rather like a double-action solenoid) - others use high pressure hydraulics to operate the valve - with electronics controlling the hydraulic pressure.
There are great advantages - the engine can be made more compact due the lack of a timing belt/chain at one end, and valve timing can be instantly varied to improve performance, drivability and emissions. There is also the option to 'switch off' cylinders - a la GM (Cadillac etc.).