Porsche 968 Variocam Assembly: Inspection Procedure and
Maintenance Schedule
Background
There have been a number of documented failures relating to the Variocam
mechanism fitted to the Porsche 968. Porsche has not published any periodic
inspection or maintenance requirements for the Variocam. Consequently even cars
with a full Porsche main dealer service history may suffer undetected excessive wear
or even catastrophic failures. In the worst case this will result in bent valves and
major engine damage. Cars that have not yet reached the stage of catastrophic failure
may still be suffering serious wear to the camshaft sprockets, requiring camshaft
replacement.
This document was produced by Derek Holliday and Ugo Manfredi. Both of us have
first hand personal experience of Variocam problems, which in each case required
replacement of both camshafts, chain, and tensioner pads. The information contained
here is based on our own experiences, and additional information obtained from the
“968.net” community and other sources.
Purpose and Scope
The purpose of this procedure is to describe a method for home inspection of the
camshaft sprockets, cam chain, and Variocam chain tensioner pads. The procedure
does not include any necessary repair work that may be necessary as a result of the
inspection findings. This procedure should be suitable for all normally aspirated 968
models. Also included is a suggested schedule with recommended inspection
intervals. These periodic inspections will provide regular checks of the health of your
Variocam and its related parts and should ensure that wear or other problems are
detected before they result in catastrophic failure.
Overview of Variocam Operation
Due to the apparent lack of detailed information on Variocam operation from
Porsche, the following section is based on the authors’ understanding, derived from
various articles and personal observations.
Variocam is a mechanism that allows the intake camshaft timing to be varied for
different engine operating conditions, thereby maximizing torque. In the 968 engine,
the exhaust camshaft is driven by a toothed rubber belt from the crankshaft. Halfway
along the length of each camshaft is a toothed sprocket and a connecting chain that
transfers drive to the intake camshaft from the engine driven exhaust camshaft.
Earlier variants of Porsche’s 16 valve engines (2.5 liter 944S and 3.0 liter 944S2) used
a similar setup but without the Variocam mechanism. Instead, they used a simple
spring and hydraulic operated chain tensioner whose purpose was simply to maintain
constant chain tension. A fundamental difference between these earlier engines and