Cam Phaser Issue & Warranty Info

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spack

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I found some stuff... This is a patent of an improvement to prior art. https://patents.google.com/patent/US20050188933A1/en

In the patent the prior art is described as I described it; a channel to the advance chamber to retract (eject) the lock pin. And a problem with the prior art is described as follows:

  • [0005]
    To permit rotation of the rotor, the pin is retracted by pressurized oil flowing from the ADJACENT ADVANCE CHAMBER VIA A CHANNEL in the sprocket face. However, in some instances the pressure build-up in the advance chamber is rapid enough and large enough that the pin becomes bound in the well before there is sufficient pressure to cause it to withdraw, thus causing the phaser to be unable to alter the valve phase as demanded. Therefore, means are needed to ensure that the pin will not be stuck in the locked position when rotor rotation is required.



    I think this was the crux of this problem, although in our case, the pin does not quite get stuck. Pressure in the advance chamber builds while the pin is locked. The pressure is sufficient to TRY to advance the locked CAM rotor. That attempted advancement pushes the locked pin against the right hand (clockwise) side of the lock pin hole. That same advance pressure also attempts to eject the pin which is bound by friction against the lock pin hole. It's a potentially abrasive movement and over time it wears the hole in that typical tapered fashion we see in many pictures of the problematic phasers. The H3LZ...-CD part has an improved means to channel oil under the lock pin, perhaps requiring less pressure to eject it. The CD part also looks like it would guide the pin better, not allowing it to become unaligned as it moves upward out of the hole. As I say, I think it's a tricky problem so solve with code but not impossible. And the new part goes a long way towards assisting the code. I wonder if the code tries to more gently build advance pressure as a means to eject the pin without too much rotor advance force. I also wonder if in the new part, the spring constant on the locking pin has been reduced to allow lower pressure to eject.



 

SoCalGen2

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I just had the cam phasers replaced on my truck today. Service advisor said everything was covered under an emission warranty and I paid nothing out of pocket. It was a nice surprise for me anyhow. Good Luck with your repair.
How many miles do you have on your truck?
 

STHenry

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My truck had 50,080 when this was completed. Seems once it hit 50,000 it just wanted to go to the dealership. i just had an oil leak repaired a week prior to this. They replaced the rear main seal for that. No proble since
 

spack

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Regarding my post #52. I picked up used MLZ and HL3Z...-CD exhaust phasers and took them apart. Neither showed wear, but I don't know their respective histories .... I learned something taking them apart and I don't want to be the source of bad info so some corrections. The post is mostly correct in concept BUT... The parked position is fully advanced. It's not a mid-locking phaser as I stated. It is the action of unlocking the phaser with retard direction (not advance direction) oil pressure which, in the previous incarnations of that phaser, may have caused the wear we see, since the oil pressure will try to move the phaser while it also moving the lock pin out. Since bias spring helps to keep it advanced while the pin is being moved, it should help reduce the shear force on the lock pin hole.

Differences in MLZ vs H3LZ. The MLZ vane depth is increased. So less oil pressure will move the rotor. The bias spring has a higher spring constant in accordance. The lock pin hole is completely passive with regard to oil channeling. In the HL3Z part, the lock pin hole has channeling from the retard chamber to the bottom of the lock pin hole. On the MLZ part this is done from the back of the lock pin and then around the pin and into the hole.

I'm sure this is of little interest, but I'll fix the mistakes in $52 regardless. Or delete it altogether. Might be best if I keep quiet.
 

spack

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Hangon... I was seemingly not wrong on post #52. It's simply that the intake and exhaust have different locking locations and feed from different chambers. The exhaust lock pin ejects on retarding oil pressure. The intake ejects on advance pressure. The exhaust phaser lock position is full advance. The intake is either full retard or in the middle. I don't have one so I don't know. Post #52 was observations of an intake phaser.
 
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