One of the most common issues that cause Porsche engine noise for about five to ten seconds during startup is a weak timing chain tensioner that does not maintain hydraulic pressure when the engine is turned off and parked for an extended period.
- Engine rattle noise at startup
- Excessive timing chain slack
- Check engine light on
- Engine runs rough
- Engine won't stay running.
- Record the timing marks before you start work.
- Replace one tensioner at a time.
- Verify timing marks before starting the engine.
- After you replace each tensioner, crank the engine by hand two full revolutions before you start it.
What you will need
In this guide, we will go over the instructions on how to change Porsche left lower timing chain tensioner with the engine in the car.
Pictures in this guide are from a Porsche Cayenne with a V8 engine, but the procedure should help you change the tensioners on other Porsche models as well.
- Park the Porsche on a level surface and allow the engine to cool down.
- Jack up the vehicle and remove the lower engine covers. On top of the engine, remove the plastic trims and, if needed, the intake air hose to access the front of the engine.
- Place a socket on the crankshaft pulley and rotate the crankshaft to bring it to TDC. Use the Porsche timing tool or an 8mm Allen wrench to lock the crank pulley to the block.
- Lock the crankshaft (and, when required, the camshafts) in position. It is crucial to lock the crankshaft to prevent the timing chain from jumping when the tensioner is removed. Also, we recommend locking the camshaft as well. To lock the camshaft, you need to remove the green cam seals on each cam cover.
- Locate the tensioners. Porsches have up to three tensioners. IMS chain tensioner and bank 4-6 tensioner can be replaced with the engine in the car. Bank 1-3 tensioner may require accessories to be removed to access it.
- Use a 27mm socket and ratchet to break loose the tensioner. Note that the tensioner has lots of threads; therefore, it will take a lot of turning to remove it. Replace one tensioner at a time.
- Prime the new tensioner. Soak the new tensioner in engine oil; while it is soaked in oil, pump it a few times to prime it.
- Install the new tensioner.
- Replace the next tensioner.
- Don't start the engine yet. Remove the locking pins. Turn the engine by hand two full revolutions to make sure there is no interference.
- Next check, the timing marks are lining up correctly. This will allow you to make sure the timing didn't jump.
Always replace one tensioner at a time. Check your work by turning the engine by hand two full revolutions.
In some cases, a rattle noise is present when the vehicle is parked for several weeks or months. This is normal unless you experience engine noise on startup when the vehicle is parked overnight.
It is recommended to get your car diagnosed by a professional Porsche mechanic to confirm the tensioners are the culprit.
Another common problem on Porsche vehicles is IMS bearing failing and is often misdiagnosed as a bad timing chain tensioner.