Question:
Have you ever seen the bottom cam belt pulley slipping on C20XE Standard engine used for racing? In other words the key for the pulley has slipped around the crankshaft therefore destroying all 16 Valves. As I have a couple of these engines, I wondered is this a common problem and if so what can be done to prevent it?
Answer:
We do know of the problem. It isn’t very common and usually only occurs in competition engines where the driver uses the gearbox instead of the brakes. What can happen under these conditions is that you get a shock loading through the flywheel. Sometimes the flywheel bolts will come loose, when this happens the shock continues on through the crankshaft. This will occasionally loosen the front crank bolt. On the 2.0L XE engine, the key way is only there for location, it has no strength. The gear itself is prevented from slipping by the extremely high torque setting of the crank bolt. The only other time we have seen the crank gears move, is if the correct torque procedure has not been used. Some people have even used Loctite on this bolt and that is definitely wrong and is more likely to cause the crank gear to come loose because the Loctite will usually prevent the bolt from clamping sufficiently on the crank gear. The thread of the bolt should always be lubricated and graphite grease should be placed on the underside of the head of the bolt. Then follow the torque sequence, which is laid down, on our web site (under Instruction Sheets).
We have personally never experienced a crank gear coming lose on any engines we have put together, but on our 2.0L steel crankshaft we put in a second key.
Update April 2021:
The standard 2.0L crank gear is now no longer available for either the earlier or later XE versions and we have designed a steel pulley as opposed to the original sintered version. The whole design has been changed because the original version was quite heavy and we have made the completely new version that incorporates 2 keyways to allow the use of Woodruff key (the twin Woodruff keys were designed for use with the earlier sintered drive gears on high specification engines using our steel cranks and have been maintained to give extra protection). These new versions are available with the poly-vee alternator drive pulley and can have an external trigger wheel added too.
Please see our shop for Pre93 version & Post93 version of our crank gear.
Category:
Vauxhall Specific