open gas tank FORD SIERRA 1988 2.G CVH Engines Workshop Manual

1.8 litre (R6A type) engine
Note: Unless otherwise stated, the Specifications for this later version of the 1.8 litre CVH engine are as given for the earlier R2A type above.
General
Engine code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .R6A
Maximum continuous engine speed . . . . . . . . . . . . . . . . . . . . . . . . . . . .5700 rpm
Maximum engine power (DIN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64 kW at 5200 rpm
Maximum engine torque (DIN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .145 Nm at 3000 rpm
Valve timing
Inlet opens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24º BTDC
Inlet closes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .116º BTDC
Exhaust opens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .110º ATDC
Exhaust closes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18º ATDC
1.6 litre engine
The 1.6 litre CVH engine was introduced in
September 1991, to replace the 1.6 litre
SOHC engine used previously in the Sierra
range. The engine is broadly similar to the 1.8
litre (R2A type) CVH engine described below.
The main differences are outlined in the
following paragraphs.
The centre main bearing is fitted with
thrustwashers to control crankshaft endfloat,
instead of a flanged bearing shell.
The hydraulic cam followers operate in a
similar manner to those described for the 1.8
litre (R2A) engine but no rollers are fitted, and
the base of each cam follower is in direct
contact with the cam profile.
A distributorless ignition system is used and
a blanking plate is therefore fitted to the cylinder
head in place of the distributor drive. The
electric fuel pump is mounted in the fuel tank.
A comprehensive emissions control system
is fitted, comprising Central Fuel Injection
(CFI), a sophisticated engine management
system, a crankcase ventilation system, a
catalytic converter, and a pulseair system (to
reduce exhaust gas emissions).
Unless otherwise stated, all procedures are
as described for the 1.8 litre (R2A) engine.
1.8 litre (R2A type) engine
The CVH (Compound Valve angle,
Hemispherical combustion chambers) engine
is of four-cylinder, in-line, single overhead
camshaft type. The engine was introduced to
replace the 1.8 SOHC engine previously used
in the range.
The crankshaft incorporates five main
bearings. The centre main bearing has a
flanged bearing shell (thrust bearing) fitted to
the cylinder block to control crankshaft endfloat
The camshaft is driven by a toothed belt and
operates the compound angled valves via roller
type hydraulic cam followers, which eliminates
the need for valve clearance adjustment. The
cam followers operate in the following way.
When the valve is closed, pressurised engine
oil passes through ports in the body of the cam
follower and the plunger into the cylinder feed
chamber. From this chamber, oil flows through
a ball type non-return valve into the pressurechamber. The tension of the coil spring causes
the plunger to press the rocker arm against the
valve and to eliminate any free play.
As the cam lifts the cam follower, the oil
pressure in the pressure chamber increases
and causes the non-return valve to close the
port to the feed chamber. As oil cannot be
compressed, it forms a rigid link between the
body of the cam follower, the cylinder and the
plunger which then rise as one component to
open the valve.
The clearance between the body of the cam
follower and the cylinder is accurately designed
to meter a specific quantity of oil as it escapes
from the pressure chamber. Oil will only pass
along the cylinder bore when pressure is high
during the moment of valve opening. Once the
valve has closed, the escape of oil will produce
a small amount of free play and no pressure will
exist in the pressure chamber. Oil from the feed
chamber can then flow through the non-return
valve into the pressure chamber so that the
cam follower cylinder can be raised by the
pressure of the coil spring, thus eliminating any
play in the arrangement until the valve is
operated again.
As wear occurs between rocker arm and
valve stem, the quantity of oil which flows into
the pressure chamber will be slightly more
than the quantity lost during the expansion
cycle of the cam follower. Conversely, when
the cam follower is compressed by the
expansion of the valve, a slightly smaller
quantity of oil will flow into the pressure
chamber than was lost.
To reduce valve clatter when the engine is
started, a small plastic stand pipe retains oil
inside the plunger. When the engine is started,
the reservoir in the plunger (and via the non-
return valve, the pressure chamber) are
immediately filled with oil. This reduces the
noise often associated with hydraulic cam
followers as they pressurise with oil after
engine start-up.
The cam follower rollers run in needle
bearings, which greatly reduces friction as the
rollers follow the cam profile.
The distributor and fuel pump are driven
directly from the camshaft and the oil pump is
driven directly from the front of the crankshaft.
The cylinder head is of crossflow design,
with the inlet manifold mounted on the right-
hand side and the exhaust manifold mounted
on the left-hand side.
Lubrication is by means of a bi-rotor pumpwhich draws oil through a strainer located
inside the sump and forces it through a full-
flow filter into the oil galleries where it is
distributed to the crankshaft and camshaft.
The big-end bearings are supplied with oil via
internal drillings in the crankshaft. The
undersides of the pistons are supplied with oil
from drillings in the big-ends. The hydraulic
cam followers are supplied with oil from the
camshaft bearings via short passages in the
cylinder head.
A semi-closed crankcase ventilation system
is employed whereby piston blow-by gases
are drawn from the crankcase, through the
camshaft cover via an external vent hose, out
to an oil separator built into the base of the air
cleaner.
1.8 litre (R6A type) engine
The 1.8 litre (R6A type) CVH engine,
introduced in March 1992, is a further
development of the earlier 1.8 litre (R2A type)
unit described above. Apart from minor
engineering modifications to provide
increased fuel economy, reliability and power
output, the engine is mechanically identical to
the earlier version.
In common with the 1.6 litre unit, a
distributorless ignition system is used,
together with a comprehensive emissions
control system comprising Central Fuel
Injection (CFI), a sophisticated engine
management system, a crankcase ventilation
system, a catalytic converter, and additionally,
an exhaust gas recirculation (EGR) system.
Unless otherwise stated, all procedures are
as described for the 1.8 litre (R2A type)
engine.
Refer to Section 2, Chapter 2, Part A.
Refer to Chapter 1, Section 35.
Refer to Section 5, Chapter 2, Part A.
4Compression test
3Crankcase ventilation system -
inspection and maintenance
2Engine oil and filter - renewal
1General information
CVH engines 2C•5
2C