78801T Mercruiser LEVER, INTERMEDIATE THROTTLE

Removing And Refitting Cylinder Head
Removing The Head:
1. Remove manifolds, air cowling and baffles, fuel piping.
3-1 Important:Be sure to plug up all open fuel pipe connections. When removing No. 2 head on F2L, remove fan to gain access to rear stayplate of baffles. Fastenings of stayplate of F2L are shown in Fig. 3-2.
3-22. Remove injector, if necessary using puller No. 110030 and tool No. 150800 (see Section 7).3. Remove rocker chamber cover and rocker arm bracket.Fig. 3-3
3-34. Remove pushrods and plugs.Fig. 3-4
3-45. Release cylinder head bolts crosswise and in stages by wrench No. 120040/120050 and remove.Fig. 3-5
3-56. Remove head and pushrod cover tubes.2. Refitting:
7. Position cylinder head. Note for Refitment:Should work on the head have affected the piston top clearance, adjust clearance (see Section 2).8. Insert head bolts with washers and preload. On F2L align heads by steel rule after intake flanges.Fig. 3-6
3-6 Note for Refitment:Replace any strained bolts. (Maximum length see Specification Data).9. Tighten bolts crosswise through specified torques, using wrench No. 120040/120050 and device No. 101900.Fig. 3-7
3-710. Fit brass plugs and new washers in head.Fig. 3-8
3-8 Note for Refitment:Use only brass plugs for replacement.11. Fit spring on cover tube and compress by special tool No. 125300.Fig. 3-9
3-912. Fit washer and seal at tube bottom end and seal at top end.Fig. 3-10
3-1013. Introduce tube with spring end into tappet hole of crankcase and introduce opposite end into hole of cylinder head. Withdraw spring compressing tool.Fig. 3-11
3-1114. Insert pushrods and fit rocker arm bracket.Fig. 3-12
3-1215. Set valve clearance (see Section 2).16. Stick new gasket with sealing compound to rocker chamber cover, position cover, align and screw in bolt with new washer.17. Fit injector with washer or heat shield, as applicable to the particular model. (See also Section 7).18. Fit injector bridge and tighten nut as specified.Fig. 3-13
3-1319. Fit new gaskets for manifolds.20. Mount manifolds.Fig. 3-14
3-1421. Fit air baffles.22. Fit fan. Tighten bolts as specified.Fig. 3-15
3-1523. Connect fuel piping.Fig. 3-16
3-16Overhauling The Rocker Arm Bracket
1. Dismantle bracket.Fig. 3-17
3-172. Replace any worn parts.3. When replacing bearing bush, check that oil holes mate.Fig. 3-18
3-18 Note for Refitment:The rocker arms are provided with an oil metering screw, the chamfered face of which should point to the thrust pad (Fig. 3-19). Check that one thread turn of the screw projects beyond the locknut.When the screw is finally adjusted under idling conditions on the engine test bench or in a vehicle, the position of the chamfered face is irrelevant. All you have to make sure is that a small oil flow toward the thrust pad is still visible.
3-19Inspecting Pushrods, Cover Tubes And Tappets
Fig. 3-201. Check that rod ends are tightly seated and free from wear.2. Check that rods are straight and oil hole is free.3. Check that tubes are straight and free from defects.4. Check that tappets are not worn and oil hole is free.Replace parts as required.
3-20Overhauling The Cylinder Head
1. Mount head on bracket No. 120900 c/w plate No. 120910.2. Compress valve springs by tool No. 121120 (Fig. 3-21). Remove taper collets, springs with caps, rotators and valves.
3-213. Clean head, inspect for external defects and replace as required.4. For overhauling head, proceed as follows.5. Check that head seat is smooth and flat (Fig. 3-22). Remachining is possible, provided the head bottom/seat distance is not smaller than stated in the Specification Data.Fig. 3-23
3-22
3-236. Minor defects of the seat can be removed by grinding head on liner with compound. Major damage is eliminated by cutter No. 124480 (Fig. 3-24) or clamping device No. 125500 for a lathe as described hereafter.
3-247. Clamp down head by device No. 125500 in lathe and align.Fig. 3-25
3-25 Important:Remove no more material than absolutely necessary.Fig. 3-26
3-26 Note for Refitment:Check that head bottom/seat distance does not exceed the limit provided in the Specification Data.Inspecting Valves, Valve Stems And Seats
Inspecting Valve Guide:
8. Measure stem/guide clearance by regular gauge (see Specification Data).Fig. 3-27
3-27Replacing Valve Guide:
9. Heat cylinder head to 220°C or so in an oven.10. Press out old guides by arbor No. 123310.Fig. 3-28
3-28 Important:For fitting oversize guides, enlargen bore in head by precision borer accordingly. Any seat inserts should be replaced along with the guides as long as the head is heated to 220°C.11. Provide new guides with circlips and introduce into heated heads with chamfered ends outside.Fig. 3-29
3-2912. When head has cooled off, ream guides by tool No. 123510.Fig. 3-30
3-3013. Gauge distance between tulip face centre and head seat.Fig. 3-31
3-31Remachining Valve Seat Inserts:
14. Remachine inserts by cutter No. 122320.Fig. 3-32
3-32 Note for Refitment:If remachining limits (see Specification Data), are liable to be exceeded, replace inserts or valves respectively.