Porsche 968 Cam Maintenance
The Porsche 968, 944S2 and 944 S all used dual overhead cams, unlike the previous 8v engines. This also introduces a slightly different maintenance schedule for the cam system. The 8v engines were all more or less cam maintenance free, with the exception of oil seal replacements as they started to leak. The DOHC heads though, all have tensioners, oil feed pipes, cam chains, and tensioner pads to worry about. The 944 line is fairly basic in terms of maintenance. The tensioner pads can easily be replaced without pulling the cams from the head. The 968 variocam system is a bit different. To replace the tensioner pads which wear due to the cam chain riding on them, the cams have to be pulled out of the head, tensioner removed from the cams, and then the pads can be replaced, so it is a bit more complex. A combination of the pads wearing, and the cam chain stretching over time will cause excessive wear on the teeth of the cam, which will become very expensive when you have to replace the cams, or the system fails, and takes out your head.
This 968 was coming up on it’s timing belt service, and since the cam maintenance records were non-existant from the previous owner, it was time to go in and check them out. The car spurng a fairly excessive oil leak over the winter, and so the maintenance had to be done.
First things first, was to tear into the belts and waterpump and get them replaced. The oil leak turned out to be a combination of the upper and lower balance shaft front seals leaking, so all the front seals were replaced, new waterpump, belts and rollers. To do the cam maintenance, the timing belt has to be at least removed from the cam pulley, so it is a good overlapping job.
With the top valve cover removed and everything lined up on TDC, you can see the cams lined up as they should be. Note the white paint marks I placed on the chain, and the cam. In that spot on the cam, there is a raised arrow, which is your guiding point for installing the cams. The arrows should be 7 links apart on the chain.
Next up was removal of the cams. The cams and tensioner must be removed as one unit.
Once out of the engine, the cams can be laid on a nice soft towel, and you can work on getting the tensioner out. The tensioner must be compressed in order to slide off the cams.
Once the tensioner is free from the cam and chain, you can remove and replace the chain pads. Typically the top pad is the most worn, but in this case, the bottom pad definitely showed more wear. Notice the grooves in the pad. The surface should be smooth. Also notice the old style pads are a dark brown, and the new pads are tan.
With the new pads installed, a new chain can be installed, and the tensioner reinstalled in the cams, and installed back on the car.
And the front end starting to go back together……
If you are careful, you can take steps to make sure your cam timing is not disturbed when doing this job. Make sure to use a lot of assembly lube on the cam and carriers when going back together!