1999 Mercury MerCruiser GM V-8 305 CID (5.0L) & 350 CID (5.7L) Marine Engine Service Manual #24 (P/N 90-861327--1)

Mercury Marine Service Manual No. 24 covers 1999 MerCruiser GM V-8 305 CID (5.0L) and 350 CID (5.7L) marine engines in Alpha/Bravo sterndrive and MIE inboard/Ski configurations. The base publication is 90-861327--1, October 1999.

Text search, bookmarks and wiring detail: Body text is searchable, including the supplement; some illustration labels are not. Small wiring codes require zooming. Section bookmarks are provided, but the 5E bookmark opens the supplement, and the Models Covered link points to a separate file that is not included.

• Engine repair: Removal and installation, cylinder-head and valve-train service, crankshaft and piston inspection, oil-pump disassembly, and bearing-clearance specifications.

• Fuel systems: Mercarb 2-barrel carburetor overhaul and adjustment, Cool Fuel system repair, Throttle Body EFI service, and multi-port injection component replacement.

• MEFI diagnostics: MEFI 1, MEFI 2 and MEFI 3 circuit checks, trouble-code charts, injector balance testing, and idle-air-control functional tests.

• Electrical systems: Thunderbolt V ignition testing, base timing procedures, starter and alternator service, instrumentation checks, and starting/charging and fuel/ignition harness diagrams.

• Cooling and exhaust: Seawater-pump overhaul, closed-cooling pressure tests, winterization, exhaust manifold and riser service, and Silent Choice exhaust troubleshooting.

• Transmissions and shafts: Velvet Drive and Hurth removal, installation, shift-cable adjustment and pressure testing, plus drive-shaft repair and propeller-shaft alignment checks.

• Power steering: Pump and pulley replacement, hose and cooler service, system bleeding, and serial-specific serpentine-belt routing.

Mercury Marine wrote this manual for dealer mechanics and company service personnel already trained in marine service procedures and the required shop tools.

Engine Service and Alignment

The engine repair section documents component identification, rotation, and internal lubrication clearances for crankshafts, piston assemblies and valve trains. Cylinder-bore inspection, valve-seat conditioning, camshaft-bearing installation and torque tables support internal overhaul work. Separate maintenance schedules cover MCM and MIE installations.

Installation coverage distinguishes MCM engine-to-drive alignment from MIE engine-to-propeller-shaft alignment. It identifies Quicksilver alignment tool 91-805475A1 and covers engine-coupler spline lubrication.

Carburetion, Fuel Injection and MEFI Diagnosis

Mercarb service includes choke, accelerator-pump and idle-mixture adjustments. The injection chapters distinguish 350 Mag MPI, Black Scorpion and Throttle Body EFI assemblies, with exploded views, fuel-system flow diagrams and vacuum/vent hose-routing views.

Separate ECM connector and EFI symptoms charts for MEFI 1/2 and MEFI 3 help match a suspect circuit to the correct controller before condemning an ECM. Normal scan-tool data, sensor reference values and diagnostic flowcharts support checks for no-start, fuel-pump relay, MAP-sensor and IAC faults, including symptoms without stored codes.

The tool lists identify the MerCruiser scan tool, Code Mate tester and Quicksilver DDT. IAC service notes explain how forcing the valve pintle can damage its internal worm drive.

MX 6.2 supplement: Publication 90-861327000, July 2000 adds Section 5E disassembly and reassembly coverage for MX 6.2L MPI and MX 6.2 Black Scorpion fuel-injection components. This addition is limited to fuel injection; it is not a complete 6.2L engine overhaul manual.

Ignition, Starting and Charging Systems

Electrical coverage separates Mercury Marine and GM EST distributors, Delco 14MT direct-drive and PG260F1 starters, and Mando and Delco Remy alternators. Mando repair procedures and Delco Remy specifications accompany battery-isolator diagrams, gauge/sender checks and audio-warning circuits.

Cooling, Winterization and Exhaust

Water-flow diagrams distinguish Alpha cooling layouts from Bravo, inboard and Ski arrangements. Procedures cover Quicksilver sea strainers, seawater-pump bearing housings, water circulating pumps, thermostat testing, heat-exchanger checks and winterization drain points.

Exhaust coverage includes manifolds, elbows, risers and shutters. Silent Choice material adds air-tube routing and compressor/system troubleshooting. Observe the manual's precautions for pressurized fuel, electrical isolation and hot cooling systems during service.

Transmission Service and Driveline Limits

Velvet Drive coverage includes 71C in-line, 72 Series V-drive and 5000A/5000V units; Hurth coverage includes 630A, 630V and 800A. The chapters provide fluid specifications, external service and operational tests. Internal transmission overhaul requires separate service literature. Walter RV-36 information covers identification and lubricant/capacity data.

Hurth rotation notes explain that coupling these transmissions to a right-hand-rotation engine can cause severe transmission damage. Drive-shaft extension sections cover output-shaft housings and bearing supports; sterndrive-unit repair requires the separate drive manual.

Steering Pump and Belt Variants

Serpentine-belt diagrams distinguish 0L618999 and below from 0L619000 and above. The latter also marks the alternator change to 65 amps. Steering-pump replacement and bleeding are covered; detailed steering testing and repair refer to the appropriate sterndrive manual.

PDF Contents and Included Supplement

One printable English 895-page PDF combines 853 pages of the base manual with the 42-page fuel-injection supplement. The base-manual count already includes 18 cover/front-matter pages and 38 marked blank pages; the supplement is included in the total.