Cadillac L62 V8-6-4 / Engine noise in 4 Cylinder mode

[CadillacSDV56]

Hello,

I hope someone can help me.

In 4 cylinder mode, there is a slight ticking from the engine.

Is the noise normal in 4 cylinder mode, or should no further noise occur. maybe someone had the same problem?

Thanks

Timo

[Dave Shepherd]

Tough from here to diagnose engine noises, anyway , it not unusual  to get some valve noise in the 4cyl. mode.  But how much, tough to say, based on mileage and 40 years of maintenance.

[TJ Hopland]

Do you think its detonation / pinging?  Or are you thinking its mechanical?     For detonation maybe try a tank of the highest octane fuel available in your area?   

I suppose its possible that its something in the deactivation system.  There are quite a few parts involved.  Basically how it works is there is a pair of castle like discs on the rocker pivot.   In active mode the castle disc rotates so the high points all align which means it acts as a normal pivot when the valve operates.   In de activate mode a solenoid rotates one of the discs so the castle discs interlocks which means when the pushrod pushes the whole rocker lifts and the valve doesn't open.   In theory the hydraulic lifter and springs in the castle setup should keep a preload on the system but at this age maybe something is worn, sticky, or out of adjustment.