Roinik As long as they are changed at the recommended 100,000 miles with everyday use, then there is minimal risk.
Somebody would be doing really well to get 100K miles out of one. First I've heard of a replacement schedule for them, too.
The dealership where I worked during my youth did a roaring trade in timing gears.....
My old 144 went through three sets - two before my custodianship, and one during. When the engine got rebuilt at 160K miles, it got steel gears. Steel gears were far more comparatively expensive back then. But so was the tow tuck, when I was left stranded on Parramatta Rd in peak hour. Never again!
As long as the oil supply is clean and good through that little nozzle inside the timing case, genuine Volvo Penta steel gears never need replacing. They were factory fitted to the AQ120 marine engines, so Volvo obviously knew fibre gears were a problem - or that car owners made good cash cows.
AFAIC, it's a known weakness in the engine, and the factory came up with a solution. Fibre timing gears fall into the same category as Miracle Felt oil seals, 9mm B230 rods, 55mm centre thrust crankshafts, and 'Sealed For Life' transmission service schedules.
