Valve Guide Seal: Service and Repair
Removing and installing valve-stem sealTools
Preliminary work
Note: The cylinder head can remain fitted while this work is carried out.
1. Remove engine.
2. Remove camshafts on both cylinder banks.
3. Take flat-base tappets out of the cylinder head and lay them on a clean surface, arranged according to cylinders and valves. Do not interchange components.
Information
Component overview
In the Turbo, the exhaust valve is fitted with internal and external valve springs and adapted concave washers (different to those shown in the figure below). The exhaust valve in the turbo engine has the same dimensions as the exhaust valve in the naturally aspirated engine; because of the sodium filling it is lighter however and when obtained as a spare part it features a colored dot to distinguish it. For further details, please see later chapter entitled "Valve dimensions".
Removing valve-stem seal
Note: When required, all valve-stem seals on both cylinder rows must be replaced.
Note: Before switching to another cylinder, the cylinder must be positioned at the bottom dead center and supplied with compressed air (see above).
Note:
^ Position the pistons of the relevant cylinder at the bottom dead center.
^ Each piston is pressed downwards as pressure builds up in the cylinder.
1. Set piston for the corresponding cylinder to bottom dead center. To do this, guide the timing chain carefully when turning the crankshaft.
2. Screw in compressed-air hose from the valve key assembly/disassembly tool for the Cayenne NR.54-1 tool set in the relevant spark plug bore so that it is tightly sealed. Apply compressed air constantly to cylinder (at least 6 bar overpressure). This builds up the pressure in the cylinder so that the valve does not fall into the cylinder while the work is being carried out. Replace all four valve-stem seals for a cylinder and refit valve keys. Only then fit compressed-air hose on the next cylinder and apply compressed air constantly.
3. Fit and adjust lever tool from the valve key assembly/disassembly tool for the Cayenne NR.54-1 set on the cylinder head. When doing so, ensure that the middle pipe is positioned centrally over the spark-plug recesses. The operating lever can be secured centrally or eccentrically. The fastening screws in the camshaft bearing caps in the front and rear bearing position are used to secure the tool brackets. Use the white plastic pressure piece with the magnetic insert to remove the valve keys. The assembly must be performed as shown.
4. Press the white plastic pressure piece with the magnetic insert against the top concave washer to remove the valve keys. The concave washer -2- and the valve keys -1- are attracted to the magnetic insert and release the valve (loosen valve keys with a screwdriver if they are stuck). Remove loose components (valve springs, top concave washer and valve keys). Repeat procedure for valves on pressurized cylinder (reposition tool accordingly).
5. Withdraw sliding sleeve of puller 3364. When positioning the puller 3364 on the fitted valve-stem seal, ensure that the metal edge of the valve-stem seal is positioned behind the corresponding metal edge of the puller.
6. When engaging the puller 3364, push sliding sleeve down and close tool. -arrow-
7. Remove valve-stem seal by activating the negative (slide) hammer. -arrow-. Repeat procedure for valves on pressurized cylinder (reposition tool accordingly).
Installing valve-stem seal
Note:
^ Position the pistons of the relevant cylinder at the bottom dead center.
^ Each piston is pressed downwards as pressure builds up in the cylinder.
Note: Before switching to another cylinder, the cylinder must be positioned at the bottom dead center and supplied with compressed air (see above).
Note: When required, all valve-stem seals on both cylinder rows must be replaced.
Note: Protective caps must be ordered as separate spare parts. They are reusable. They are used to protect the valve-stem seal so that it is not damaged at the valve stem end.
1. Prepare valve-stem seal -1-, protective cap -3- and assembly driver 9606/1-2-.
2. Push protective cap onto valve stem end.
3. Oil valve stem, protective cap and valve-stem seal. Push valve-stem seal with sealing lip upwards -1- over the protective cap -2- onto the valve stem. Remove protective cap.
4. Guide the assembly driver 9606/1 over the valve stem and fit the valve-stem seal by hand or by tapping it lightly using the rubber hammer as far as it will go.-arrow-
5. Fit valve springs, concave washer and valve keys. To do this, place valve springs (there are two in the exhaust valve in the turbo engine) on the bottom concave washer. Place top concave washer in position. Pull off the ring of the assembly tool -2- from the retaining springs -3- before inserting the valve keys. Position valve keys with the thin side facing upwards -1-.
6. Insert valve keys into the assembly tool with the thin side facing upwards -1-. Ensure that the valve keys fit symmetrically and are inserted as far as they will go in the assembly tool. The retaining springs are free -2-.
7. Secure the valve keys by pushing up the ring. Check that the valve keys are aligned correctly -1-.
8. Insert valve key assembly tool in tool setup and position in front of the valve stem.
9. When assembling the valve keys, ensure that the assembly tool is inserted at the valve stem end -2- and is then pushed down (the tool remains secured when this is done -1-). The valve keys click audibly into the valve grooves when the valve key assembly tool is pressed onto the valve. Check valve keys to ensure that they are installed correctly.
10. Replace all four valve-stem seals for a cylinder and refit valve keys. Only then fit compressed-air hose on the next cylinder and apply compressed air constantly.
Subsequent work
1. Fit flat-based tappets.
2. Install camshafts.
3. Install engine.
Information
Valve dimensions
