Engine - Camshaft Knock
10/2/9512/02/95/US
SUBJECT:
Camshaft Knock
MODEL:
Range Rover Classic Discovery
AFFECTED VEHICLES:
1994 and 1995 Model Year Discovery up to LJ 137600
1995 Model Year Range Rover Classic 3.9 up to LH 660001
DETAIL
Land Rover Engineering has developed a service procedure to repair a diagnosed camshaft knock on '94 and '95 MY Discovery and '95 MY Range Rover Classic 3.9 engines (Serpentine belt drive system engines). Vehicles built after the above VIN numbers have a "keeper plate" to prevent cam knock occurring.
ACTION REQUIRED
Upon customer complaint only, follow procedure below.
PARTS INFORMATION
CAM1000 - Cam Button
Order necessary fluids/gaskets for a front cover gasket replacement.
PROCEDURE
To properly diagnose a camshaft knock ensure the following procedures are completed.
The engine must reach normal operating temperature. Run the engine at approximately 2000 rpm for 2 - 3 minutes to ensure lifters are properly primed. Finally allow engine to idle. Ensure that the symptom is not a result of contamination of the drive belt (undercoating on belt and/or pulleys). It is necessary to remove the drive belt and run engine briefly to assist in the diagnosis. If the knocking/tapping noise is eliminated when the belt is removed, then the noise is being generated from the ancillary drive system, and not the camshaft.
If camshaft knock is diagnosed then proceed with the following installation instructions on page 2.
WARRANTY
COMP.CODE: 1S2K
SRO: 12.65.89/26 - Fit cam button - 3.40 hrs
1. Remove the front cover assembly following the procedure in the shop manual for replacing the front cover gasket (section 12.65.04) Do not discard the old gasket, it is required later in this procedure.
2. Using a rubber or hide mallet drift the camshaft as far into the block as possible. Tap the cam bolt until the thrust face on the camshaft is tight up to the front face of the block.
3. Remove the bolt and washer securing the camshaft sprocket and discard them.
4. Install the new replacement bolt (with the thrust button installed) and the new conical spacer. Take care not to damage the nylon button. Use a deep socket and torque to 55-60 Nm (41-44 lb.ft.)
5. Because of component tolerances engine to engine it is necessary to check the clearance of the button to the inside surface of the front cover. Use the following procedure:
Obtain a small piece of waterproof dum-dum and apply (stick) it to the exposed outermost end of the button. Leaving the old front cover gasket in place, refit the front cover and torque the 4 uppermost bolts to specification.
Now remove the bolts and the front cover and observe whether there is a film of dum-dum covering the tip surface of the button. If there is not and the nylon tip is either partially or totally exposed then this suggests the button is "hard" contacting the front cover.
If this is the case the button must be removed and it's tip filed down. The front cover clearance must then be rechecked with the dum-dum.
Do not try and file the tip of the button with the bolt installed in the camshaft nose the button will easily damage. Use a vice to hold while filing or carefully file the tip using a grinding wheel.
When a film of dum-dum is achieved over the full end surface of the button then the clearance is acceptable. (The clearance should be 0.005 - 0.010 in)
6. Remove the old front cover gasket and using a new one refit the front cover and reassemble the front end of the engine as described in section 12.65.04 of the work shop manual.