1 General information
How to use this Chapter
1 This Part of Chapter 2 is devoted to repair
procedures possible while the engine is still
installed in the car, and includes only the
Specifications relevant to those procedures.
Similar information concerning the V6 engines
will be found in Part B of this Chapter. Since
these procedures are based on the
assumption that the engine is installed in the
car, if the engine has been removed and
mounted on a stand, some of the preliminary
dismantling steps outlined will not apply.
2 Information concerning engine/trans-
mission removal and refitting, and engine
overhaul, can be found in Part C of this
Chapter, which also includes the Specifi-
cations relevant to those procedures.
Engine description
“M” series engine
3 The M16 engine fitted to Rover 820 models
is a water-cooled, four-cylinder, double-
overhead camshaft, four-stroke petrol engine,
of 1994 cc capacity. The engine was fitted to
Rover 820 models from 1986 until
approximately October 1991.
4 The combined crankcase and cylinder
block is of cast iron construction, and houses
the pistons, connecting rods and crankshaft.
The solid skirt cast aluminium alloy pistons
have two compression rings and an oil control
ring, and are retained on the connecting rods
by fully floating gudgeon pins. To reduce
frictional drag and piston slap, the gudgeon
pin is offset to the thrust side of the piston.
The forged steel connecting rods are attached
to the crankshaft by renewable shell type big-
end bearings. The crankshaft is carried in five
main bearings, also of the renewable shell
type. Crankshaft endfloat is controlled by
thrust washers which are located on either
side of the centre main bearing.
5 The twin overhead camshafts are located in
the cylinder head, and each is retained in
position by a housing bolted to the cylinder
head upper face. The camshafts are
supported by five bearing journals machined
directly into the head and housings. Drive to
the camshafts is by an internally-toothed
rubber timing belt, from a sprocket on the
front end of the crankshaft. An idler pulley and
adjustable tensioner pulley are fitted to
eliminate backlash and prevent slackness of
the belt. The distributor rotor arm is attached
to the rear of the exhaust camshaft, and on
early models, the power steering pump is
belt-driven from a sprocket attached to the
rear of the inlet camshaft. On later models, the
power steering is located at the front of the
engine, and is belt-driven from a sprocket on
the crankshaft.
6 The M16 engine utilizes four valves per
cylinder, mounted at an inclined angle, and
running in guides which are pressed into the
cylinder head. The valves are of small
diameter, to improve breathing efficiency and
reduce valve mass. Each valve is opened by a
hydraulic tappet, acted upon directly by the
lobe of the camshaft, and closed by a single
valve spring.
7 Blow-by gases from the crankcase are
vented by a positive crankcase ventilation
system back into the intake air stream for
combustion. The system incorporates an oil
separator, to return oil droplets to the sump,
and a diverter valve, which channels the
vapour to inlets on either side of the throttle
valve, depending on manifold depression.
8 The pressed-steel sump is attached to the
underside of the crankcase, and acts as a
reservoir for the engine oil. The oil pump
draws oil through a strainer attached to the
pick-up pipe and submerged in the oil. The
pump passes the oil along a short passage
and into the full-flow filter, which is screwed
onto the pump housing. The freshly filtered oil
flows from the filter and enters the main
cylinder block oil gallery, which feeds the
crankshaft main bearings. Oil passes from the
main bearings, through drillings in the
crankshaft to the big-end bearings.
9 As the crankshaft rotates, oil is squirted
from a hole in each connecting rod, to splash
the thrust side of the pistons and cylinder
bores.
10 A drilling from the main oil gallery feeds
the cylinder head gallery, via a restrictor
located just below the top face of the cylinder
block. The cylinder head contains an oil
gallery on each side, with drillings to lubricate
each camshaft journal and hydraulic tappet
bore. The oil then drains back into the sump
via large drillings in the cylinder head and
cylinder block.
11 On turbocharged engines, a take-off pipe
from the main oil gallery feeds the
turbocharger shaft bearings and then returns
to the sump via an oil return pipe.
12 A pressure relief valve is incorporated in
the oil pump housing, to maintain the oil
pressure within specified limits.
“T” series engine
13 The T16 engine fitted to later Rover 820
and Vitesse models is a development of the
“M” series unit and is similar in most areas.
The engine was fitted to Rover 820 models
from approximately October 1991 and is
currently still in production.
14 The main differences between the two
units is in the following areas.
15 The timing belt only drives the two
camshafts; the water pump now being situated
externally on the engine, behind the power
steering pump, and driven (in conjunction with
the power steering pump) by the auxiliary drive
belt. The timing belt incorporates an automatic
tensioner to maintain correct timing belt
tension for virtually the life of the belt.
16 The semi-floating pistons are retained on
the connecting rods by interference fit
gudgeon pins.
17 The engine mountings have been revised
to improve vibration resistance and power
unit stability.
18 Other detail modifications have been
incorporated, mainly in the area of ancillary
component attachments, and these will be
covered in greater detail where procedures in
this Chapter are likely to be affected.
2 Repair operations possible
with the engine in the vehicle
The following operations can be carried out
without having to remove the engine from the
car:
(a) Compression pressure - testing.
(b) Removal and refitting of the timing belt.
(c) Removal and refitting of the camshaft and
tappets.
(d) Removal and refitting of the cylinder
head.
(e) Removal and refitting of the sump.
(f) Removal and refitting of the big-end
bearings.*
(g) Removal and refitting of the piston and
connecting rod assemblies.*
(h) Removal and refitting of the oil pump.
(i) Removal and refitting of the engine
mountings.
(j) Removal and refitting of the flywheel or
driveplate (after first removing the
transmission).
* In extreme cases caused by a lack of
necessary equipment, repair or renewal of
piston rings, pistons, connecting rods and
big-end bearings is possible with the engine in
the vehicle. However, this practice is not
recommended, because of the cleaning and
preparation work that must be done to the
components involved, and because of the
amount of preliminary dismantling work
required - these operations are therefore
covered in Part C of this Chapter.
3 Compression test -
description and interpretation
2
1 When engine performance is down, or if
misfiring occurs which cannot be attributed to
the ignition or fuel systems, a compression
test can provide diagnostic clues as to the
engine’s condition. If the test is performed
regularly, it can give warning of trouble before
any other symptoms become apparent.
2 The engine must be fully warmed-up to
normal operating temperature, the oil level
must be correct, the battery must be fully
charged, and the spark plugs must be
removed. The aid of an assistant will also be
required.
4-cylinder engine – in-car engine repair procedures 2A•3
2A
1380 Rover 800 Series Remake
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