I just replaced the camshaft seal on one of our B230FTs. It was leaking ever so slightly, and being energetic and not tolerating oil leaks at all, I went ahead and replaced it. The nut holding the gear on the camshaft is torqued to 36 ft-lbs. The problem is holding the gear and camshaft while torquing the nut. The can turns with only a few ft-lbs of torque and you can't begin to hold against 36 ft-lbs of torqe with your bare hands. You don't want to grip the gear by its teeth and possible damage it. I think it was Don Foster who recommended using an old belt as a pad and gripping the sprocket with a large pair of channelock pliers. But if you happen to have Volvo tool 5284 for holding the harmonic balancer while torquing the crankshaft bolt, it happens that the teeth in tool 5284 match the hole pattern in the gear on my car. I just inserted the teeth of tool 5284 in the gear, and held the tool while applying 36 ft-lbs of torque. Earlier engines have solid gears, and this will not work.