spun camshaft probs in Mezger?
10-22-2015, 10:15 PM
#1
Racer
Thread Starter
spun camshaft probs in Mezger?
Have any of you guys had, or heard of this spun camshaft problem with the Mezger engine in the GT2/GT3 cars? Some guys with 997.1 Turbos have reported this problem, and it is expensive to fix. Apparently the 997.2 Turbo does not b/c it is 9A1 engine. I was just curious with the rev range so much higher on GT3, is the Mezger in the GT3 a different engine? Closer tolerances? Or are we bedeviled with this same issue...
https://rennlist.com/forums/997-turb...aft-story.html
https://rennlist.com/forums/997-turb...aft-story.html
10-23-2015, 02:12 AM
#2
Rennlist Member
Not unless you have some serious overrevs going. The variocam actuators act as a bit of a buffer in the event of an overrev, so you really need quite a bit of abuse to throw the cams out of alignment...
10-23-2015, 08:41 AM
#3
Racer
Thread Starter
^^^
I was not thinking of causing it by over revs per se, I was just wondering if the Mezger engine in a GT3 is different than the 7.1 turbo. I mean any window sticker (on a GT3) that says "Titanium connecting rods" seems to be built stout. And I know the cams are much bigger in a GT3, hopefully differnt design re the steel sleeve inside the camshaft. Apparently these camshaft spins in the turbos are happening just under normal driving in traffic. I don't know the frequency, that's why I was curious if you guys had heard of it.
A quote from a knowledgable poster on 997 turbo forum:
"This failure is a mechanical material/engineering failure. A stamped steel sleeve that is pressed into a cast iron camshaft rotates inside the hollow camshaft bore. It's random with zero notice or pattern. It's like a lottery.
There are a few theory's as to why the sleeve is turning, but they are unrelated to engine oil or lubrication as the cause.. However, when the sleeves turn, they do affect the oil movement to the variocam module.. "
I was not thinking of causing it by over revs per se, I was just wondering if the Mezger engine in a GT3 is different than the 7.1 turbo. I mean any window sticker (on a GT3) that says "Titanium connecting rods" seems to be built stout. And I know the cams are much bigger in a GT3, hopefully differnt design re the steel sleeve inside the camshaft. Apparently these camshaft spins in the turbos are happening just under normal driving in traffic. I don't know the frequency, that's why I was curious if you guys had heard of it.
A quote from a knowledgable poster on 997 turbo forum:
"This failure is a mechanical material/engineering failure. A stamped steel sleeve that is pressed into a cast iron camshaft rotates inside the hollow camshaft bore. It's random with zero notice or pattern. It's like a lottery.
There are a few theory's as to why the sleeve is turning, but they are unrelated to engine oil or lubrication as the cause.. However, when the sleeves turn, they do affect the oil movement to the variocam module.. "
10-23-2015, 11:09 AM
#4
Rennlist Member
Doesn't sound like a GT3 problem TBH
10-23-2015, 12:13 PM
#5
Racer
Thread Starter
Just confirmed with my dealer friend, the GT3 Mezger does not have this problem. It is only on the turbo, has to do with the Vario Cam Plus system. A metal sleeve can move, shut off oil to the lift of the intake valves. GT3 is fine.
10-24-2015, 09:57 AM
#6
Racer
Thread Starter
Some on the 997 Turbo forum argue it could be a harmonic, from the crankshaft, sent to the cam through the timing chains causes the little sleeve in cam to move, blocking the oil passage. It may also be more prevalent in turbo b/c of higher compression pressures. Maybe, in general, running GT3 Mezger at higher RPM than a turbo, the harmonic is maybe lessened?