Cam Chain Tensioner Replacement

Cam Chain Tensioner Replacement

Ahhhh yes, the infamous Cam Chain Tensioner. New to the 944 S2 world ?.... well, here is a brief explanation:

The exhaust cam is driven by the Cam Sprocket, which is turned by the timing belt. Simple enough, right ?

The intake cam is driven by the exhaust cam via a small cam chain that is located in the center of the cams. This chain is tensioned by a small tensioner that actually sits inbetween the top and the bottom parts of the chain.

The pictures say more than a thousand words.

Camshaft arrangement, note chain connecting middle of cams

Here it is, the infamous tensioner itself. The orangish-red plastic ramps are the wear surfaces.

When I removed the old plastic ramp, it was so brittle it broke into two pieces.

Here is the new tensioner pad installed on the existing tensioner.

The replacement interval on this part is the topic of a lengthy and ongoing debate. Some guys say 45,000 miles. Some guys say 60,000 miles, and some guys say 100,000 miles. The reason for the debate is that PCNA, to my knowledge, has never specified a replacement interval for this part .

So here's the punchline..... when this thing breaks, the plastic ramp breaks off and the chain then catches the metal clip just below the plastic. Porsche conveniently made this piece perfectly square so that the chain would catch the tab, break the chain and likely the tensioner assembly. When the chain breaks, valves and possibly pistons are destroyed, and potentially even the head is destroyed. The cost of this failure is usually between $3000.00 and $5000.00. The part costs about $250.00. The repair can be performed by even a novice in about an hour or so. Cheap insurance, right ?

Now, there is another route available to make matters more complicated.... The plastic ramp is now available from Zims Autotechnik. It is the general consesus of the most knowledgable S2 gurus that replacing only the ramp is not a good idea. Their opinion is that when the original ramp has worn down, the hydraulic part of the tensioner is also ready for replacement. However, some guys are taking this route to save money....The ramp is only $25.00. The jury is still out on who is right because the ramp has only been available for a few months. I recently replaced just the ramp on my 1989, at 92,000 miles. I plan on replacing the entire assembly within a year.

Replacement Procedure

Read the entire procedure through several times and visualize each step before beginning this repair. I do not take any responsibility for any damage done to your car while using this procedure.

Remove the spark plug wires and spark plugs. If you keep the plug wire holders "clipped" together, it makes it easier to keep the wires in order. Just unscrew the holders and remove the wires as a group.
Remove the xx bolts that secure the cam cover to the head. They do not unscrew all the way out, but they can be pulled through the rubber grommets in the cam cover. Removing the bolts makes it easier to remove the cover itself and reduces the risk of catching a bolt on a cam, bearing, etc.
The cam cover can be removed without removing the fuel rail hoses with just the right amount of twisting, lifting and turning. Be patient and work it out slowly.
Once the cam cover is removed, place some paper towels or clean rags into the spark plug holes. (See 2nd picture above) You don't want a washer or bolt falling into the cylinder, do you?
Remove the two bolts that hold the "J-tube" onto the tensioner and head. There are four small copper "crush" washers that form a seal for the oil that feeds the tensioner, two on top of the J-tube and two on bottom.Carefully remove these after removing the bolts. Remove the J-tube and then remove the bottom two crush washers. The bottom washers may stick to the J-tube if you are lucky, saving you the experience of trying to fish a small, thin, oil covered washer out of your head.
Carefully press down on the chain with your hand and compress the tensioner. As the tensioner is compressed, insert a very small allen wrench into the hole in the metal tensioner tab and above the plastic ramp. This will hold the tensioner in the compressed position for removal.
Remove the two bolts that hold the tensioner to the head. Once these bolts are removed the entire tensioner assembly can be removed.
Reverse the procedure to install, make sure you use new crush washers and preferably, new bolts as well. Torque the tensioner bolts to 7 ftlbs and the valve cover bolts to 7 ftlbs.