H2

This is not out of my 968 BTW...but a 928...but the timing gears are similar. Warn cam gears are not uncommon in 928s, usually caused by a too tight Tbelt. In this case, the hub behind the gear was bent causing the gear to rotate a bit "off" wearing out the gear....but it took 40K miles to do it!

When worn the cam gears' plated covering wears off or gets shiney, sharp edges occur, and you sometimes get some cupping on top of each gear. Guess which gear is new?

Harvey

RajDatta

Harvey, just curios, what kind of tensioners do 928's use? Also, how is it adjusted?
Thanks.
Raj

H2

Raj,

The 928's weak point (other than the longest cam belt on a car in history) is the belt tensioner. It is not auto adjusting, like the 968. It's a unit filled with bronze washers and oil that expands as the engine heats up...thereby increasing the tension a bit. It's not precise and is the cause of a lot of heart failures, if not grenaded engines. You adjust it by a tensioning screw until you get a belt tension of 5.2..then recheck it at 1500 miles or when the Belt Tens warning light comes on.

A friend of my in Portland, OR has adapted a Ricer auto tensioner to the 928 and is driving it around in Alpha test mode right now. Would be great if it works. But because of the seriousness of the effects if it doesn't work, no one else is experimenting with it right now. The very early 928s were non-interference engines but all the rest can experience serious head damage, just like the 968...only there are TWO heads to repair.

Why Porsche never adopted the much better design of the 968 auto tensioner for their high priced GTS, I'll never know.

I'll post pics of the 928 tensioners.

Harvey

PorscheDude1

YIKES!

RajDatta

Thats what I say as well!!
Raj