The CAM Phaser issue is not lack of oil pressure on start up. Its the locking pin not seating correctly at shut down to save the base timing. This is the entire concept of the CAM Phasers since there is no oil pressure at start up. The timing runs on the VCT Solenoid which is oil powered so when engine is off there needs to be a way to lock the timing.
One trick that seems to work for some people with CAM Phaser rattling is before shutting down let it idle of a minute or more this somehow helps the Phaser Pin to lock better. Not a fix but a stop gap maybe until Ford addresses this.
Agreed. Under normal operation engine oil is ported to the phaser via the solenoid. The amount of oil directed to the phaser is variable, which results in advancing/ retarding the mechanical timing of the camshafts.
Agreed. The engine has no oil pressure on cold starts, and relies on the pin to “lock” the two concentric halves of the phaser together at the base timing position. It holds this position until oil pressure is sufficient to start doing its normal job again.
Agreed. Those engines experiencing the loud knock for 2 seconds on a cold start are hearing it, because the pin is not locking the two halves of the phaser together. And that is the sound of the two halves slapping violently back and forth as the outer half is being suddenly driven by the timing chain (around the crankshaft). And the inner half (connected to the camshafts) vainly struggles to keep up.
For those thinking this “isn’t really a problem”, eh.. ok.
After two or three seconds, enough oil pressure exists for the solenoids and phasers to do their job.
Where we differ in opinion is the root cause.
The failure mode, as I understand it, is that on some engines, the VCT solenoids are experiencing inadequate oil pressure early in the start. This has been validated by NDE at Ford, and measured by additional instrumentation test runs on engines pulled from vehicles that had multiple VCT failures.
This sub-optimal oil pressure is believed to be a result of inadequate sealing at the megacap end of the shaft. Since oil pressure builds too slowly at the megacap following the engine start, no oil pressure makes it into the phaser to disengage the pin and resume normal operations.
So as a result the pin stays locked in FOR TOO LONG—much longer than it is supposed to. This side shearing action on the pin is what is responsible for that worn, irregular looking “ramp”. Because the pin isn’t cleanly disengaging on startup. What you are seeing in that photo is a symptom of the problem—not the root problem, which is inadequate oil pressure at the megacap.
But, you don’t see or hear this. It just happens. Over. And over. And over… until (30,000 miles later) the repeated stresses on that puny little pin result in fatigue failure, and ‘snap!’
The pin breaks.
And then the next time you go perform a cold start….. KNOCK KNOCK KNOCK.
who’s there?
Ford Makulako guy has a video showing one these broken pins. That part is not theory. Mine had one broken pin, and one degraded.
Is it simply due to the phaser pins not engaging on some of these engines? Sure, that’s possible.
Could it be a combination of those two popular theories? I’d say likely.
Will we ever know the whole story? Hell no, then Ford would have to replace a lot of long blocks.
www.expeditionforum.com
