Check your lifters...
#1
05-05-2010, 09:03 AM
Join Date: Jun 2005
Location: Virginia, USA
Posts: 8,510
Rep Power: 788 
Check your lifters...
Before you have a failure like I did. It seems to be a problem with the 996. Porsche replaced the lifters in the 997...for good reason.
Found out today that my liners are fine. Pistons are fine. Headgaskets are fine.
What happened? My stock lifter pins have been backing out over time and created a groove inside the bore. The lifter then got stuck, which caused my piston to hit my valve.
*Had nothing to do with tuning.
*Had nothing do with pump gas.
*Had nothing to do with power.
Todd Knighton told me he has seen this 3 times now. The other two cars were K16 cars.
When Mike used the boroscope, he saw a reflection that looked at the time like it was a bowed out/bulged liner. A mirage.
Regardless, Mike stopped what he was doing and thus saved my head and pistons.
We are now pressing forward with replacing my rods, liners, cam housing and intake valves.
Pics to follow...
Found out today that my liners are fine. Pistons are fine. Headgaskets are fine.
What happened? My stock lifter pins have been backing out over time and created a groove inside the bore. The lifter then got stuck, which caused my piston to hit my valve.
*Had nothing to do with tuning.
*Had nothing do with pump gas.
*Had nothing to do with power.
Todd Knighton told me he has seen this 3 times now. The other two cars were K16 cars.
When Mike used the boroscope, he saw a reflection that looked at the time like it was a bowed out/bulged liner. A mirage.
Regardless, Mike stopped what he was doing and thus saved my head and pistons.
We are now pressing forward with replacing my rods, liners, cam housing and intake valves.
Pics to follow...
#2
05-05-2010, 09:08 AM
Before you have a failure like I did. It seems to be a problem with the 996. Porsche replaced the lifters in the 997...for good reason.
Found out today that my liners are fine. Pistons are fine. Headgaskets are fine.
What happened? My stock lifter pins have been backing out over time and created a groove inside the bore. The lifter then got stuck, which caused my piston to hit my valve.
*Had nothing to do with tuning.
*Had nothing do with pump gas.
*Had nothing to do with power.
Todd Knighton told me he has seen this 3 times now. The other two cars were K16 cars.
When Mike used the boroscope, he saw a reflection that looked at the time like it was a bowed out/bulged liner. A mirage.
Regardless, Mike stopped what he was doing and thus saved my head and pistons.
We are now pressing forward with replacing my rods, liners, cam housing and intake valves.
Pics to follow...
Found out today that my liners are fine. Pistons are fine. Headgaskets are fine.
What happened? My stock lifter pins have been backing out over time and created a groove inside the bore. The lifter then got stuck, which caused my piston to hit my valve.
*Had nothing to do with tuning.
*Had nothing do with pump gas.
*Had nothing to do with power.
Todd Knighton told me he has seen this 3 times now. The other two cars were K16 cars.
When Mike used the boroscope, he saw a reflection that looked at the time like it was a bowed out/bulged liner. A mirage.
Regardless, Mike stopped what he was doing and thus saved my head and pistons.
We are now pressing forward with replacing my rods, liners, cam housing and intake valves.
Pics to follow...
#3
05-05-2010, 09:14 AM
Join Date: Jun 2005
Location: Virginia, USA
Posts: 8,510
Rep Power: 788 Thanks.
One thing to note is that a few of the other lifter pins in my car have started to back out as well. Thus, I think it's probably happening on quite a few cars out there.
#4
05-05-2010, 10:23 AM
Is this related to mileage? Boost? something else? I wonder what specifically is causing them to back out.... Thanks for posting.. I will get mine checked next time I have the Car at my Mechanic...
#6
05-05-2010, 10:43 AM
Join Date: Jun 2005
Location: Virginia, USA
Posts: 8,510
Rep Power: 788
Todd at Protomotive told me it has nothing to do with boost, and/or power...and my car only has 8k miles on it.
#7
05-05-2010, 10:45 AM
Any and all information on what caused yours to back out would be very useful.
Glad you caught it before it caused a major problem for you.
Keep us up to date on how your rebuild goes...
Cheers.
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#10
05-05-2010, 11:39 AM
Join Date: Jun 2005
Location: Virginia, USA
Posts: 8,510
Rep Power: 788
Here's an email from Todd K.:
Originally Posted by protomotive
After removing the valve cover and looking at the lifter bore, you'll be able to see evidence of this problem on a fully assembled engine. Besides the factory machined groove around 4 oclock, you may see two approximately 4mm grooves being worn/machined into the housings by the lifter pins backing out.
They'll be a 3 and 9 oclock in the bore and should not be there. So if there's any 3 or 9 oclock grooves, there's gonna be a problem!
The lifters have been superceded for the 996t, not only for the 997t, so this was obviously a problem on the first revision of these lifters.
Scott's car is a 2003 GT2, so it's not just relegated to the early 01's or 02's.
Hennessey's car we fixed was an 01 996t. The other car at Prototech I'm not sure of the year.
They'll be a 3 and 9 oclock in the bore and should not be there. So if there's any 3 or 9 oclock grooves, there's gonna be a problem!
The lifters have been superceded for the 996t, not only for the 997t, so this was obviously a problem on the first revision of these lifters.
Scott's car is a 2003 GT2, so it's not just relegated to the early 01's or 02's.
Hennessey's car we fixed was an 01 996t. The other car at Prototech I'm not sure of the year.
#13
05-05-2010, 11:58 AM
Join Date: Jun 2005
Location: Virginia, USA
Posts: 8,510
Rep Power: 788
The lifter pins are pressed. If they did a bad job at the factory pressing them in, they can fail.
My last turbo never had this issue and it had a lot more miles on it.
Regardless, my motor will be stonger tha ever when it's complete.
My last turbo never had this issue and it had a lot more miles on it.
Regardless, my motor will be stonger tha ever when it's complete.
#14
05-05-2010, 12:05 PM
I guess if the lifter pins back out and score the lifter bores you need to replace the cylinder heads or can the bores be repaired?
Also can you inspect the lifters with the camshafts in?
Also can you inspect the lifters with the camshafts in?