each cylinder head, and is retained in position
by a housing bolted to the cylinder head
upper face. The camshafts are supported by
bearing journals machined directly into the
head and housings. Drive to the camshafts is
by an internally-toothed composite rubber
timing belt, from a sprocket on the front end
of the crankshaft. The belt also drives the
water pump pulley, and an automatic
tensioner is fitted to eliminate backlash and
prevent slackness of the belt.
6 The camshafts operate slippers which pivot
on hydraulic tappets, one for each valve. The
inlet valves are operated directly from the
camshaft slippers, whereas the exhaust
valves are operated indirectly from the
camshaft slippers by pushrods and adjustable
rocker arms (see illustration).
7 The 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.
8 The distributor is attached to the rear of the
front facing cylinder head and is driven off the
rear of the camshaft. The power steering
pump and alternator are mounted on top of
the engine and driven by separate drivebelts
from the crankshaft pulley.
9 Blow-by gases from the crankcase are
vented by a positive crankcase ventilation
system back into the intake air stream for
combustion.
10 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 passage and into
the full-flow filter and oil cooler assembly,
mounted on the front of the engine. The
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.
11 A drilling from the main oil gallery feeds
the cylinder head gallery, where the oil is
directed to the camshaft bearings, cams and
cam slippers, and to the hydraulic tappets,
rocker arm pivots and rocker arm shafts. The
oil then drains back into the sump via large
drillings in the cylinder head and cylinder
block.
12 A pressure relief valve is incorporated in
the oil pump, to maintain the oil pressure
within specified limits.
13 Apart from minor development
differences, both the 2.5 and 2.7 litre versions
of the engine are mechanically identical.
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.
Precautionary note
Due to the layout of the V6 engine, and the
very limited space available in the engine
compartment, access to most components is
extremely limited. Although it is physically
possible to carry out the operations described
above with the engine in the car, the space
restrictions, the number of components that
need to be removed for access, and the
complications involved when working on an
engine of this complexity, may present
unforseen difficulties.
Read through all the relevant procedures
and familiarize yourself with what’s involved
before proceeding; in many instances, it may
actually be easier to remove the engine from
the car, and carry out the repair with the unit
on the bench. Strictly speaking, much of the
work described in this Chapter is not for the
faint-hearted, and should really only be
undertaken by the more experienced DIY
owner.
3 Compression test -
description and interpretation
Refer to Part A, Section 3.
4 Top Dead Centre (TDC) for
number 1 piston - locating
2
General
1 Top Dead Centre (TDC) is the highest point
that each piston reaches as the crankshaft
rotates. While each piston reaches TDC both
at the top of the compression stroke and
again at the top of the exhaust stroke, for the
purpose of timing the engine, TDC refers to
the piston position (usually No 1 piston) at the
top of its compression stroke.
2 It is useful for several servicing procedures
to be able to position the engine at TDC.
3 No 1 piston and cylinder are at the right-
hand (timing belt) end of the engine (right- and
left-hand are always as seen from the driver’s
seat), on the rear bank (ie under the brake
master cylinder). The crankshaft rotates
clockwise when viewed from the right-hand
side of the vehicle.
Locating TDC
4 Remove the small plastic plug from the
viewing hole on the front of each timing belt
upper cover (see illustration).
V6 engine - in-car engine repair procedures 2B•3
1 Camshaft
2 Hydraulic tappet
3 Inlet valves
4 Inlet valve slippers
5 Exhaust valves
6 Exhaust valve
slippers
7 Pushrods
8 Rocker arms
9 Tappet body
10 Plunger
11 Check ball
12 Return spring
1.6 General arrangement of the V6 engine
valve gear
4.4 Remove the plastic plug from the
viewing hole on each timing belt upper
cover
2B
1380 Rover 800 Series Remake
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