hi i've just bought a luguna 1.9 dci. It's done 49,000 miles and requires a cam belt. the Haynes manual says a special electronic tool is required to set up the tension. where can this be obtained or is there another method?
Hi, and welcome. What your looking for is a Harmonic guage or a SEEM tool, both measure the tension of the belt to the figures that Renault specify (ask your workshop controller or RTE at your local dealer nicely, or buy one of the many "settings" books that are available, but they are costly ... each engine series and application is likely to be different.)
The SEEM tool is a meter that measures the static tension of the belt, and costs approx £300 new, the Harmonic guage measures the vibration of the belt when running and calculates the tension, I believe they are in the £400-£500 mark.
The old rule of thumb (twist the belt through 90 degrees, or deflection of X at the centre of the belt) will work to get you started, but the setting should really be checked .. maybe a local garage or dealer will check it for you .. at a price of course.
A belt that is too slack or too tight will fail premeturely, and as most modern engines are interference fit (ie the valves and pistons will touch), that will end up very costly if it breaks.
The Haynes manual does tell you how to tension the belt very close to the correct setting but I would take it to the dealer to check as advised, you cannot afford to not do this as if anything goes wrong it will be extremely expensive to repair the damage.
Perhaps someone on here will know more than me on this.
I was going to delete my post due to the excellent answer above but due to the cost of the gauges doing it this way could still be an option.