Intake Manifold: Service and Repair

Fig. 9 Cylinder Component Removal:

Fig. 10 Exploded View Of Cylinder Heads:

Refer to Figs. 9 and 10 when removing and replacing cylinder head.
1. Disable airbag system as described under Technician Safety Information.
2. Drain coolant.
3. Remove camshaft timing pulleys. Refer to Timing Belt.
4. Disconnect accelerator, throttle and cruise cables from throttle body.
5. Remove spark plug wire clamps.
6. Remove lower spark plug wire cover, then the ignition coil.
7. Remove water inlet and inlet housing assembly, then the timing belt rear plates.

Fig. 11 Fuel Pressure VSV Removal:

Fig. 12 Vacuum Pipe Removal. LS 400:

Fig. 13 Vacuum Pipe Removal. SC 400:

8. Remove EGR pipe, then the fuel pressure VSV, Fig. 11.
9. Remove EGR VSV, then EGR valve and modulator.
10. On California models, remove EGR valve adapter.
11. Remove vacuum pipe, Figs. 12 and 13.
12. Remove ISC valve, then the throttle body.
13. Remove accelerator bracket, then the brake booster union.
14. Remove air intake chamber as follows:
a. Disconnect cold start injector.
b. Remove union bolt and gaskets, then disconnect cold start injector from righthand delivery pipe.
c. Remove bolts and nuts to intake chamber, then remove intake chamber.
d. Remove cold start injector, tube, wire assembly and gasket.
15. Disconnect engine wire from intake manifold.
16. Disconnect engine wire from wire bracket on righthand cylinder head.
17. Disconnect heater hoses.
18. Remove delivery pipes and injectors as follows:
a. Disconnect water temperature sensor, cold start injector time switch and water temperature sender gauge connectors.
b. Disconnect connectors from wire bracket on front side of lefthand delivery pipe.
c. Remove six engine wire bolts, then the engine wire.
d. Disconnect injectors.
e. Disconnect fuel hose from fuel tube, then from fuel return pipe.
f. Remove fuel return pipe.
g. Remove four nuts, wire bracket, two delivery pipes, eight injectors, four spacers and eight insulators. Do not drop injectors.
19. Remove intake bolts, then the intake manifold.
20. Remove front water bypass joint, then the rear water bypass joint.
21. Remove front exhaust pipe, then the main catalytic converters.
22. Remove righthand exhaust manifold.
23. Remove oil dipstick and guide.
24. Remove lefthand exhaust manifold.
25. Remove engine hangers.
26. Remove engine wire brackets from righthand head.
27. Remove cylinder head covers.
28. Remove semi-circular plugs, if necessary.
29. Remove camshafts as follows:

Fig. 14 RH Drive Gear/sub-gear Alignment:

Fig. 15 RH Exhaust Cam Alignment:

Fig. 16 RH Exhaust Cam Loosening Sequence:

a. Bring service bolt hole of righthand exhaust camshaft upward by turning exhaust cam with wrench. Secure cams by placing service bolt through sub-gear and driven gear, Fig. 14.
b. Set timing mark of exhaust camshaft driven gear at 10° angle by turning cam with wrench, Fig. 15.
c. Remove two bearing cap bolts holding oil feed pipe, then loosen and remove bearing cap bolts in sequence in Fig. 16. After bolts are removed, remove oil feed pipe, bearing caps and camshaft.

Fig. 17 RH Intake Cam Alignment:

Fig. 18 RH Intake Cam Loosening Sequence:

Fig. 19 LH Drive Gear/sub-gear Alignment:

d. Set timing mark of righthand intake camshaft at 45° by turning cam with wrench, Fig. 17.
e. Remove bearing cap bolts in sequence in Fig. 18. When all bolts are removed, remove bearing caps, oil seal and intake cam.
f. Bring service bolt hole of lefthand exhaust camshaft upward by turning exhaust cam with wrench. Secure cams by placing service bolt through sub-gear and driven gear, Fig. 19.

Fig. 20 LH Exhaust Cam Alignment:

Fig. 21 LH Exhaust Cam Loosening Sequence:

Fig. 22 LH Intake Cam Alignment:

Fig. 23 LH Intake Cam Loosening Sequence:

g. Set timing mark of exhaust camshaft driven gear at 15° angle by turning cam with wrench, Fig. 20.
h. Remove two bearing cap bolts holding oil feed pipe. Then loosen and remove bearing cap bolts in sequence in Fig. 21. After bolts are removed, remove oil feed pipe, bearing caps and camshaft.
i. Set timing mark of lefthand intake camshaft at 60° by turning cam with wrench, Fig. 22.
j. Remove bearing cap bolts in sequence in Fig. 23. When all bolts are removed, remove bearing caps, oil seal and intake cam.

Fig. 24 Cylinder Head Bolt Loosening Sequence:

30. Disconnect ground straps at rear of heads. Remove all cylinder head bolts in sequence shown in, Fig. 24, then remove cylinder heads.
31. Reverse procedure to install, noting the following:
a. Refer to Specifications for torque values.

Fig. 25 Cylinder Head Bolt Tightening Sequence:

Fig. 26 Seal Packing Locations:

b. Follow the head bolt tightening sequence, Fig. 25.
c. Install new circular plugs to heads. Apply seal packing to bearing caps, Fig. 26.

Fig. 27 RH Cam Installation Alignment:

Fig. 28 LH Cam Installation Alignment:

d. Once an intake and exhaust cam is installed, ensure to line up timing marks on the cams, Figs. 27 and 28.

Fig. 29 RH Cam Tightening Sequence:

Fig. 30 LH Cam Tightening Sequence:

e. Tighten camshaft bearing bolts in the sequence, Figs. 29 and 30.
f. Check and adjust valve clearance. Refer to Valve, Intake/Exhaust.
g. Rearm airbag system as previously described.