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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 

Summary of Contents for 968 - ASSEMBLY INSPECTION PROCEDURE AND MAINTENANCE SCHEDULE

Page 1: ...ny 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...

Page 2: ...er pistons each having a plastic rubbing pad that acts directly onto the upper and lower chain runs The distance between the upper and lower tensioner pads is maintained by an internal spring supplemented by constant engine oil pressure when the engine is running This spring and oil pressure maintains correct chain tension in a similar fashion to the earlier 944 series cars The vertical position o...

Page 3: ...effective pitch of the chain links accelerating wear of the camshaft sprockets 3 Variocam on off action As described above the Variocam is on intake timing advanced in the 1 500 to 5 500 rpm range and off outside this range The engagement of the chain with the intake exhaust camshaft sprockets differs between these two positions and this may affect the wear patterns on the sprocket teeth The weari...

Page 4: ...rces Also when working on the engine it s very easy to dent the front wings fenders by leaning on them Place soft covers old blankets are ideal over them to prevent scratches and don t lean on them Tools Required 17mm and 19mm good quality open ended spanners wrenches Strong light source Old rags Inspection mirror small dentists type is ideal Hexagon drive bits sizes 4mm and 5mm and suitable drive...

Page 5: ...e or stay attached to the cam cover When withdrawing the cover it s often needed to peel the seal away from parts of the engine or cover IF COVER SCREWS ARE STILL IN THE COVER TAKE CARE THAT THEY DON T FALL OUT AND DROP INTO THE EXPOSED ENGINE 13 Note that there are four black circular rubber seals around the spark plug recesses These will hopefully stay attached to the engine when the cover is re...

Page 6: ...h is visibly worn on my old cams figure 3 and this will be accompanied by stretch of the chain It s very much a subjective judgement call as to how much wear is permissible but you should be able to spot an imminent disaster at least 23 It s a good idea to take your own close up photos if possible both for seeking second opinions and for later comparison purposes if all looks ok this time 24 With ...

Page 7: ...spection procedure use a small mirror to carefully inspect it as much as the limited access allows Any signs of cracking more probable at pad corners means the pads need to be changed Pay attention to signs of age leading to brittle pads more prone to future cracking the age is denoted by Dark brown color of pads new ones are light brown This is not a definitive criterion but comparing fig 4 5 6 y...

Page 8: ...tion about previous Variocam inspection maintenance as soon as possible carry out the inspection procedure detailed above Miles Km Action Unknown or greater than 60 000 Unknown or greater than 100 000 Immediately inspect the Variocam following the procedure above See also the section above regarding wear limits It is highly recommended to do the Variocam inspection before buying a new car as part ...

Page 9: ...urposes only subject to the user accepting full responsibility for any consequences resulting from use of the information contained herein Constructive feedback comments or questions are most welcome Derek Holliday drholliday compuserve com Ugo Manfredi ugo manfredi mail wind it Issue 1 April 2003 ...

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