Timing chain tensioner, crank to IMS - Porsche 911 type 996 1999-2000, Boxster type 986 1997-2000

Porsche

Genuine Porsche timing chain tensioner for early dual-chain M96 engine cars, delivered between 1997-2000. This is not for use on later production single-chain M96 or M97 engines.

Fits:

Porsche Boxster type 986, 1997-2000*
Porsche 911 C2 / C4 type 996, 1999-2000*
*Please note: Since some earlier cars may have a later production replacement engine with the single row timing chain which requires a different timing chain tensioner. It is recommended to verify which version engine you have installed in your Porsche before replacing. Sometimes a visual inspection is the only option to do so. Please contact us with any additional questions. The single chain tensioner is available here.

Notes:

Latest available revision.
For dual-chain M96 engines only.
For crankshaft to intermediate shaft.
Single groove cut into head identifies position.
Professional installation recommended.

On the M96 / M97 family of engines from Porsche there are three timing chain tensioners which keep the crankshaft, camshaft banks and intermediate shaft in time and operating correctly. Porsche has released multiple updates on these over the years, and this is one of the most simple and relatively inexpensive maintenance updates which can be performed to help with long term reliability.

As the tensioners wear from use and mileage the piston will score and over time which this can lead to binding. Significant cases of tensioner binding or excessive slop (rattling) will increase the stress and tension on the timing chain and components, and in the most severe cases can break the chain. If this occurs on the primary crankshaft to intermediate shaft chain it can lead to catastrophic total engine failure, on occasion. If it occurs on one of the camshaft bank timing chains the damage can vary, but will always be costly.

A tell-tail sign of worn or less-than-optimal tensioner condition is a 'rattle' sound at start up and when cold. Generally speaking if your Porsche's engine begins to have a 'rattle' at cold start this could be an indication of weak or worn tensioners. The tensioner is pumped up by oil to maintain proper pressure and worn tensioners will typically bleed some of this pressure off after sitting for some time, resulting in this momentary rattle from having too little tension.

As a rule of thumb if you have had your M96 or M97 Porsche 911, Boxster or Cayman for some years and are unsure if the tensioner update has been done, or if you have a rattle at cold start, or are having an IMS bearing update procedure being done it is ideal to inspect and if necessary replace these three tensioners. Visible scoring on the tensioner piston, as shown above, is a good example of a worn tensioner needing replacement.