Failed (mushroomed) lifters on M96 engines?

[elgyqc]

In Help Me DIY's (TTGator) recent forensic video on his failed 2003 2.7 Boxster engine he reveals that Jake Raby diagnosed the problem as a mushroomed valve lifter. According to Jake this is a common problem caused by an improperly machined camshaft. On cylinder one an intake valve lifter had broken and and the second one was about to fail.
The video is here, explanation is after 7:00 minutes:
https://www.youtube.com/watch?v=bN5RJRvZlUo&list=PL8ogZBhXvNyZCp7OSJEVa-qf5JN-vtkX3&index=17&t=2s

I searched for information on this failure but found nothing... does anyone have more information? Specifically, what engines are affected? My assumption is that the problem would only be with the 3 chain engines. If 5 chain engines are affected I will have to pull the valve cover and inspect the lifters on the 3.2 that I am preparing for installation in my car.

[pilot4fn]

I have 2.7 that I just replaced the chain ramps adn the lifters as well as the cams look like brand new - car has now 299.750 km with a great service history and frequent oil changes (all receipts at hand).
Last three years I have also raced it on local Porsche Racing Club.

Never heard of this kind issue, but maybe that problem (and many others) will come if the engine has not been looked after and oil has not been changed frequently.

[elgyqc]

I just had a look at the lifters on the disassembled 3.2 engine (5 chain) out of my 2000 S... all were good with normal wear.

[elgyqc]

I cross posted this thread on the Rennlist 996 forum and got some interesting answers there.
https://rennlist.com/forums/996-forum/1336189-failed-mushroomed-lifters-on-m96-engines.html#post18621319

[986tate]

Interesting.
How long do you think it would take for someone smart enough to their own IMSB to take off the valve cover and inspect?

[elgyqc]

Originally Posted by 986tate

Interesting.
How long do you think it would take for someone smart enough to their own IMSB to take off the valve cover and inspect?

From what was said on the thread on the Rennlist 996 forum
"the engine that suffers from this issue is the M96.23 which is a 3 chain 2.7 engine used only in the base model Boxster. He says that he has seen something similar with the M96.24 3.2 variant of the engine, but not very frequently. These are unique engines since they are 3 chain design, but do not utilize variocam Plus."
So if your car fits this description... not too long, the cams can't fall out when you take the valve cover off and you only have to check the intake lifters on cylinder 1.

[986tate]

I have that motor.
I won’t have to make the cam holder out of a piece of 1” L-angle and 2 Allens?
Might actually do this

[elgyqc]

Originally Posted by 986tate

I have that motor.
I won’t have to make the cam holder out of a piece of 1” L-angle and 2 Allens?
Might actually do this

If you go to 14:00 of this video you see (and Aaron explains) how the cams are held in place.
https://www.youtube.com/watch?v=wT2b2w-_9l0&list=PL8ogZBhXvNyZCp7OSJEVa-qf5JN-vtkX3&index=9

I would put the engine in TDC for that bank and lock the cams before taking the cover off. None of the lobes should be under tension at that point... I think.
I take no responsability for this free suggestion.

[986tate]

Originally Posted by elgyqc

I take no responsability for this free suggestion.

Ha, thanks! 😁
I barely remember taking apart a 996 motor 20 years ago and thinking, “what did I need this overpriced tool for?”

[pilot4fn]

Originally Posted by elgyqc

If you go to 14:00 of this video you see (and Aaron explains) how the cams are held in place.
https://www.youtube.com/watch?v=wT2b2w-_9l0&list=PL8ogZBhXvNyZCp7OSJEVa-qf5JN-vtkX3&index=9

I would put the engine in TDC for that bank and lock the cams before taking the cover off. None of the lobes should be under tension at that point... I think.
I take no responsability for this free suggestion.

Remember also to take the chain tensioners out after you have locked the engine to TDC and locked the cams in place.. After that you can remove the camcovers.