SERVICE MANUAL NUMBER 25
262 CID (4.3L) ENGINES
Cylinder Head
The cylinder heads are made of cast iron and have individual intake and exhaust ports for
each cylinder.
Stainless steel or graphite composition head gaskets are used to retard corrosion.
Valve Train
The valves and valve springs are of a heavy-duty design to withstand the high engine
speeds encountered. Valve tips have been hardened to extend valve life. Exhaust valve
rotators are used to help extend valve life.
Hydraulic valve roller lifters ride directly on the camshaft lobes and transmit the thrust of the
lobes to the push rods which in turn actuate the valves through the rocker arm.
In addition to transmitting thrust of the cam lobes, the hydraulic lifters also serve to remove
any clearance (lash) from the valve train to keep all parts in constant contact.
The roller lifters are restrained from rotating by two retainers (restrictors) located in the
valley. The valve lifters also are used to lubricate the valve train bearing surfaces.
Intake Manifold
The manifold is of the single level design for efficient fuel distribution. All passages are of
approximately equal length to assure more even fuel-air mixture to the cylinders.
Lubrication System
The engine lubrication system is of the force-feed type in which oil is supplied under full
pressure to the crankshaft, connecting rods, camshaft bearings and valve lifters, and is
supplied under controlled volume to the push rods and rocker arms. All other moving parts
are lubricated by gravity flow or splash.
A positive displacement gear-type oil pump is mounted on the rear main bearing cap and
is driven by an extension shaft from the distributor (which is driven by the camshaft). Oil from
the bottom of the pump in the rear of the oil pan is drawn into the oil pump through an oil
pickup screen and pipe assembly.
If the screen should become clogged, a relief valve in the screen will open and continue to
allow oil to be drawn into the system. Once the oil reaches the pump, the pump forces the
oil through the lubrication system. A spring-loaded relief valve in the pump limits the
maximum pump output pressure.
After leaving the pump, the pressurized oil flows through a full-flow oil filter. On engines with
an engine oil cooler, the oil also flows through the cooler before returning to the block. A
bypass valve allows oil to bypass the filter and oil cooler should they become restricted.
Some of the oil, after leaving the oil cooler and/or filter, is routed to the No. 4 crankshaft main
bearing. The remainder of the oil is routed to the main oil gallery, which is located directly
above the camshaft and runs the entire length of the block. From the main oil gallery, the
oil is routed through individual oil passages to an annular groove in each camshaft bearing
bore. Some of the oil is then used to lubricate camshaft bearings. The remainder of the oil
is routed to the valve lifter oil galleries and No. 1, 2 and 3 crankshaft main bearings by means
of individual oil passages which intersect with the annular grooves.
The camshaft bearings have holes which align with the oil passages or annular grooves in
the block and allow oil to flow in-between the bearings and the camshaft journals. The oil
that is forced out the front end of the No. 1 camshaft bearing drains down onto the camshaft
drive and keeps it lubricated.
Index
90-861328--1
NOVEMBER 1999
Page 3A-13
| Categories | Mercury MerCruiser Manuals |
|---|---|
| Tags | Mercury MerCruiser 1262 CID, Mercury MerCruiser 262 CID |
| Model Year | 1998, 1999, 2000, 2001 |
| Download File |
|
| Document File Type | |
| Copyright | Attribution Non-commercial |
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