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Home >> Jaguar >> 1990 >> XJ-S Base, 2D Convertible >> Repair and Diagnosis >> Engine Performance >> Engine Controls - Adjustments >> Engine Mechanical >> Valve Clearance

Valve Clearance

NOTE: Chain Tensioner Releaser/Retainer (JD50), Camshaft Sprocket Retainer (JD40), and Timing Gauge (C3993) are tools needed when valve adjustment is necessary.
  1. Release fuel pressure. Disconnect wire from inertia switch. Inertia switch is located on driver's side footwell on the front door pillar. Remove coil wire leads and crank engine for 5 seconds.
  2. Disconnect negative battery lead. Discharge A/C system and disconnect A/C hose from fuel cooler. Disconnect Air Temperature Sensor (ATS) from left air filter housing. Release clips and remove both air filters and housings. Disconnect auxiliary air valve hose from left air filter backplate.
  3. Disconnect auxiliary air valve inlet hose. Disconnect crankcase breather hose from air filter backplate. Remove both left and right air filter backplates and gaskets from throttle housing. Disconnect fuel pipe retaining bolts from left and right side overrun valves. See Fig 1 .
    Fig 1: Exploded View Of Overrun Valve
    G90C15570Courtesy of JAGUAR CARS, INC.
  4. Mark and disconnect vacuum lines from intake manifolds. Disconnect fuel regulator from fuel rail. Disconnect fuel lines from fuel cooler. If necessary, remove fuel injector rail. Disconnect canister purge hose and crankcase vent hose from intake manifolds.
  5. Disconnect ignition amplifier connections and remove amplifier from intake manifold. Disconnect throttle cable from throttle pedestal. Remove both throttle rods (left and right side) from bell-cranks. Disconnect wire connectors from transmission kickdown switch.
  6. Disconnect brake vacuum hose from rear of left intake manifold. Remove both air rail hoses to check valve. Remove manifold nuts and washers. Remove air rails from intake manifold. Remove intake manifolds and gaskets from cylinder head. Remove cam cover nuts, bolts and washers. Remove cam covers and gaskets.
  7. Ensure camshaft bearing caps are tight. Check valve adjustment with engine cold. Rotate engine and check valve clearances between heel of cam and cam follower. Record each valve clearance reading. Remove rubber grommet from front of timing cover. Grommet is located on right side of timing cover just above the water pump.
  8. Insert chain tensioner releaser/retainer through the timing cover access hole. With a twisting motion, release the locking catch on the timing chain tensioner. See Fig 2 . Install chain tensioner releaser/retainer.
    Fig 2: Retracting Timing Chain Tensioner
    G90D15571Courtesy of JAGUAR CARS, INC.
  9. The hook on chain tensioner releaser/retainer arm fits into a slot on tensioner. Pull up on chain tensioner releaser/retainer and retract the timing chain tensioner until the locking catch is engaged. See Fig 2 .
  10. Rotate engine until timing gauge can be inserted into the recess in the left camshaft. See Fig 3 . Note the 2 upper uppermost camshaft sprocket retaining bolts. Remove timing gauge and rotate engine until the 2 lower camshaft sprocket retaining bolts become accessible.
    Fig 3: Checking Camshaft Timing
    G90E15572Courtesy of JAGUAR CARS, INC.
  11. Using a punch, open lock tabs and remove the 2 lower retaining bolts. Rotate engine to TDC position and refit timing gauge. Remove 2 remaining camshaft sprocket bolts and fit camshaft sprocket retainer to camshaft sprockets. See Fig 4 .
    Fig 4: Securing Camshaft Sprocket
    G90F15573Courtesy of JAGUAR CARS, INC.
    CAUTION: DO NOT  rotate engine while the camshaft sprocket is disconnected from camshaft. Serious damage can occur to valve train components.
  12. Remove camshaft bearing caps one at a time, starting from center. Note bearing cap to camshaft tower relationship. Corresponding numbers are marked on the bearing cap and cam tower. Remove left camshaft. Note original location and remove cam followers.
  13. Remove valve adjusting pads one at a time. Measure pad thickness using a 1" micrometer and note reading. Subtract correct valve clearance from clearance obtained. Select adjusting pads equal to measurement and install on top of valve spring collar.
  14. Adjusting pads are available from .085-.110" (2.16-2.79 mm) in increments of .001" (.03 mm). Pads are coded with letters "A" to "Z", each letter corresponding to a thickness increase of one size. Install camshaft followers into their original locations.
  15. Lubricate camshaft journals with clean engine oil. Install camshaft using timing gauge to position camshaft correctly. Install bearing caps and progressively tighten nuts to 96-120 INCH lbs (11-13.5 N.m). Ensure timing gauge is in position.
  16. Engage camshaft sprocket to the camshaft. Install 1 lock tab and bolt. Remove timing gauge and camshaft sprocket retainer. Rotate engine and install remaining lock tabs and cam sprocket retaining bolts. Tighten to 17-20 ft. lbs. (23-27 N.m). Recheck valve clearances and repeat adjustment procedure if necessary. Repeat steps 12) through 16) for right side valve adjustment.
  17. Fit chain tension retainer and raise the timing chain tensioner slightly. Insert release tool through the timing cover access hole. Release the locking catch and allow tensioner to expand. Remove chain tension retainer and release tool.
  18. Install new rubber grommet in front timing cover. Clean cam cover gasket surfaces. Install new rear cam cover seals and gaskets. Install cam covers. Tighten bolts to 96 INCH lbs. (11 N.m). To complete installation, reverse removal procedure. Service A/C system.
XJS VALVE CLEARANCE SPECIFICATIONS (1)

Application In. (mm)
Intake & Exhaust .012-14 (.30-36)
(1) Adjust valves with engine cold.
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