Toyota 1 MZ–FE Manual page 3

EG2–3
1MZ–FE ENGINE – ENGINE MECHANICAL
The 1 MZ–FE engine has 6 cylinders in a V arrangement at a bank angle of 602. From the front
of the RH bank cylinders are numbered 1–3–5, and from the front of the LH bank cylinders are
numbered 2–4–6. The crankshaft is supported by 4 bearings inside the crankcase. These
bearings are made of copper and lead alloy.
The crankshaft is integrated with 9 semi counterweights for balance. Oil holes are placed in the
center of the crankshaft for supply oil to the connecting rods, bearings, pistons and other
components.
This engine's firing order is 1–2–3–4–5–6. The cylinder head is made of aluminum alloy, with
a cross flow type intake and exhaust layout and with pent–roof type combustion chambers. The
spark plugs are located in the center of the combustion chambers.
At the front and rear of the intake manifold, a water passage has been provided which connects
the RH and LH cylinder heads.
Exhaust and intake valves are equipped with irregular pitch springs made of special valve spring
carbon steel which are capable of following the cam profile at all engine speeds.
The RH and LH exhaust camshafts are driven by a single timing belt, and a gear on the exhaust
camshaft engages with a gear on the intake camshaft to drive it. The camshaft journal is
supported at 5 places between the valve lifters of each cylinder and on the front end of the
cylinder head. Lubrication of the cam journals and gears is accomplished by oil being supplied
through the oiler port in the center of the camshaft.
Adjustment of the valve clearance is done by means of an outer shim type system, in which valve
adjusting shims are located above the valve lifters. This permits replacement of the shims without
removal of the camshafts.
The timing belt covers consist of the resin type No.2 and No.1 above and below the engine RH
mounting bracket.
Pistons are made of high temperature–resistant aluminum alloy, and a depression is built into the
piston head to prevent interference with the valves.
Piston pins are the full–floating type, with the pins fastened to neither the piston boss nor the
connecting rods. Instead, snap rings are fitted on both ends of the pins, preventing the pins from
falling out.
The No.1 compression ring is made of steel and the No.2 compression ring is made of cast iron.
The oil ring also is made of a combination of steel and stainless steel. The outer diameter of each
piston ring is slightly larger than the diameter of the piston and the flexibility of the rings allows
them to hug the cylinder walls when they are mounted on the piston. Compression rings No. 1 and
No.2 work to prevent gas leakage from the cylinder and the oil ring works to clear oil off the
cylinder walls to prevent it from entering the combustion chambers.
The cylinder block is made of aluminum alloy with a bank angle of 602. It has 6 cylinders which
are approximately 1.6 times the length of the piston stroke. The top of the cylinders is closed off
by the cylinder heads and the lower end of the cylinders becomes the crankcase, in which the
crankshaft is installed. In addition, the cylinder block contains a water jacket, through which
coolant is pumped to cool the cylinders.
The No. 1 and No.2 oil pans are bolted onto the bottom of the cylinder block. The No. 1 oil pan is
made of aluminum alloy. The No.2 oil pan is an oil reservoir made of pressed sheet steel. An oil
pan baffle plate keeps sufficient oil in the bottom of the No.2 oil pan even when the vehicle is
tilted. This dividing plate also prevents the oil from sloshing when the vehicle is stopped suddenly
and the oil shifts away from the oil pump suction pipe.
Plastic region tightening bolts are used for the cylinder head, main bearing caps and connecting
rods.