VarioCam Plus Lifter Failure

Hi all, Wanted to document this here as I have not been able to find much about this type of failure. Picked up my 996.2 back in October and recently noticed a ticking/tapping sound. Completely independent of engine load, but at a frequency exactly half the rotation speed of the engine, so I assumed it was something valve train related - probably a hydraulic lifter. It actually went away for a while, but then came back with a vengeance. It seemed to get louder each time I drove the car, so I parked it. Starting doing some googling and and the general consensus was not promising, with most videos I could find with noises identical to mine pointing to bore scoring. Listening closely with an engine stethoscope led me to believe the sound was loudest near the valve train, and I could not hear anything at all near the cylinder bores, which gave me some hope. I finally found some time this weekend to tear the cam cover off and this is what I found: COMPLETE lifter failure. All the components of the lifter had become loose from each other, and the outer portion of the lifter (the portion used for high lift) was completely seized in the lifter carrier. The lobes on the camshaft are pretty chewed up, but the damage could have been far worse. Here's what I think happened - Since these lifters are curved at the top and not flat, their orientation MUST be maintained to correctly interface with the lobes on the camshaft. Somehow, this lifter experienced some force causing it to overcome the feature that normally prevents this rotation (the pin protruding from the side of the lifter and the corresponding groove in the bore in the housing). When the lifter rotated (eventually by a full 90 degrees!), that caused the force from the camshaft lobes to be unevenly distributed across the top of the lifter, causing it to rock back and forth in the bore, destroying the lifter housing and the camshaft. Ultimately I'm not sure what actually caused the lifter to rotate in the first place but I figured you guys would appreciate the carnage. Anybody have a bank 1 intake cam they'd like to sell me?

I was lucky and had a cam deviation reading done and mine was +5 on bank one and +7 on bank two....so I was close to having issues......brought it to a local INDY and had the pads and several other items replaced at the same time and got out of there $6600 poorer! :P). But it saved me from having a 3000 lbs paperweight in the garage. Thats the thing, you can find cheap 996's but chances are VERY likely they will need this done! My car had 113K on it.

What's crazy is the engine only has about 15,000 miles on a complete rebuild! Not sure what the cam deviations were, but the cam locking tool went right in with the engine locked at TDC, so they must have been pretty close to nominal. I'm almost wondering if somehow something went wrong during assembly that led to this failure, but I'm not sure how that's even possible as there's only one way to install these lifters.

The lifters may have been reused. They are very expensive and it needs 12 of them. These have been redesigned several times and the 997 version that is current is much more reliable. Still very expensive!

Below I am quoting from a Jake Raby post : "Noisy lifters won't lead to big booms, but they can lead to broken lifter cradles from the excess side loading of the lifter traveling further before contacting the valve. The collapsed lifters always lead to excess valve lash, which is what creates the noise. They never stick "open", always "closed" (or collapsed) It is imperative when changing lifters to have the lifter carrier measured for taper and excess wear at the 6-12 O clock positions. Not doing this spells certain death to lifters at around 8K miles at the wear eff3etcs the lifter rotation during operation and increases wear dramatically. We've learned this the hard way during test work and even in one of our updated engines. The lifter carrier is part of the problem with noise in some instances, BUT until a worn lifter carrier is used with new or modified lifters the issues don't really become apparent. I've only had two warranty repairs since we've been providing M96 engines, both were due to slightly worn lifter carriers that were not replaced that lead to failed lifters. Neither of those caused any other engine damage, but one of them did cost me a trip to Oregon and I had to replace the lifters and components in my client's garage.. Thank goodness he was a cool guy! Now the car is still running perfect. You can get into real trouble reusing lifter carriers with new lifters, unless you know what to measure and where and good luck finding any wear specs, because they don't exist. Experience taught us whats allowable, but now we simply replace the lifter carrier no matter what .. Thats where part of the 20K price tag for my engine comes from."

Those lifters were re-used in the "wrong place" .. when re-using lifters that are already broken in and mated to a cam lobe they MUST be put back in order and on the same cam lobe ...Not keeping track of the order or just randomly placing them can in some instances cause the cam to place excess forces on the twisting/turning ... The Vario + intake cam/lifters are designed to "NOT TURN" ... all other lifters and the non-plus intake are design to "spin" while running .. The cam lobes are ground at a very slight angle on all lobes for non-plus engines to induce a spinning motion to keep wear even, and the vario-+ intakes are ground "Flat" due to necessity of design to keep from trying to "spin" the lifter.. Jakes comments were pertaining to the Non-plus lifters...but good insight on the cradle wear for either ...

Quotes source post: 20077194

Skip, what would you do regarding the lifter cradle when replacing intake lifters on a Vario + motor? Leave it? Replace it? Asking for a friend...

Quotes source post: 20077781

I would very carefully inspect and measure the bores for wear ,ovality,and taper ..if not confident in your ability or don't have the equipment then I would take them to a precision machinist to have it done and if any doubt replace them...