LAND ROVER DISCOVERY 1999 Workshop Manual

MANIFOLDS AND EXHAUST SYSTEMS - V8
30-2-6 DESCRIPTION AND OPERATION
Exhaust manifolds
Two handed, cast iron exhaust manifolds are used on the V8 engine. Each manifold has four ports which merge into
one flanged outlet positioned centrally on the manifold.
Each manifold is attached to its cylinder head with eight Torx bolts. Each bolt is fitted with a 'cotton reel' shaped spacer
which allows for a longer bolt resulting in increased torque loading on each bolt. Two laminated metal gaskets seal
each manifold to its cylinder head. The flanged outlet on each manifold provides the attachment for the front pipe of
the exhaust system.
Exhaust system
The exhaust system comprises a front pipe assembly with two front pipes each incorporating a catalytic converter, an
intermediate pipe incorporating a silencer and a tail pipe assembly which also has a silencer. The exhaust system is
constructed mainly of 63 mm (2.48 in) diameter extruded pipe with a 1.5 mm (0.06 in) wall thickness. All pipes are
aluminized to resist corrosion and the silencers are fabricated from stainless steel sheet.
Front pipe assembly
The front pipe assembly is of welded and fabricated construction. A front pipe from each exhaust manifold merges
into one flanged connection. Two captive studs on the flange provide attachment to the intermediate pipe with
locknuts. Each front pipe has a welded flange which is attached to each manifold and secured with three studs and
flanged nuts and sealed with a metal laminated gasket. The gasket comprises a heat resistant fibre between two thin
metallic layers to enhance the sealing properties of the gasket.
A catalytic converter is located in each front pipe. The catalytic converters are different shapes to allow clearance
between the body and transmission. Both catalytic converters are of similar internal construction.

+ EMISSION CONTROL - V8, DESCRIPTION AND OPERATION, Emission Control Systems.
CAUTION: Ensure the exhaust system is free from leaks. Exhaust gas leaks upstream of the catalytic
converter could cause internal damage to the catalytic converter.
From the catalytic converters, the front pipes merge into one pipe which terminates at a flanged joint. The flange
connects with the intermediate pipe, sealed with an olive and secured with studs and locknuts.
Intermediate pipe and silencer
The intermediate pipe is of welded and fabricated tubular construction. It connects at its forward end with a flange on
the front pipe assembly and is secured with locknuts to captive studs in the front pipe assembly flange. The rear
section of the intermediate pipe connects to the tail pipe assembly via a flanged joint, sealed with a metal gasket and
secured with locknuts and studs.
The forward and rear sections are joined by a silencer. The silencer is fabricated from stainless steel sheet to form
the body of the silencer. An end plate closes each end of the silencer and is attached to the body with seam joints.
Perforated baffle tubes inside the silencer are connected to the inlet and outlet pipes on each end plate. Internal baffle
plates support the baffle tubes and together with a stainless steel fibre absorb combustion noise as the exhaust gases
pass through the silencer.
The intermediate pipe is attached by two brackets, positioned at each end of the silencer, and mounting rubbers to
the chassis. The mounting rubbers allow ease of alignment and vibration absorption. The two mounting rubbers are
fitted with removable heat deflectors to prevent heat from the silencer damaging the material.
Tail pipe assembly
The tail pipe is of welded and fabricated construction. It connects to the intermediate pipe with a flanged joint secured
with studs and locknuts and sealed with a metal gasket. The pipe is shaped to locate above the rear axle allowing
clearance for axle articulation. The pipe is also curved to clear the left hand side of the fuel tank which has a reflective
shield to protect the tank from heat generated from the pipe.
A fabricated silencer is located at the rear of the tail pipe. The silencer is circular in section and is constructed from
stainless steel sheet. A baffle tube is located inside the silencer and the space around the baffle tube is packed with
a stainless steel fibre. The holes in the baffle tube allow the packing to further reduce combustion noise from the
engine. The tail pipe from the silencer is curved downwards at the rear of the vehicle and directs exhaust gases
towards the ground. The curved pipe allows the exhaust gases to be dissipated by the airflow under the vehicle and
prevents gases being drawn behind the vehicle.
The tail pipe is attached by a bracket, positioned forward of the silencer, and a mounting rubber to the chassis. The
mounting rubber allows ease of alignment and vibration absorption.

MANIFOLDS AND EXHAUST SYSTEMS - V8
REPAIRS 30-2-7
REPAIRS
Front pipe
$% 30.10.09
Remove
1.Release front HO2S multiplugs from support
brackets and disconnect multiplugs.
2.Raise vehicle on ramp. 3.Where fitted, release rear HO2S multiplugs
from support brackets on transfer box and
disconnect multiplugs.
4.Remove 8 bolts securing cross member and
remove cross member.

MANIFOLDS AND EXHAUST SYSTEMS - V8
30-2-8 REPAIRS
5.Remove 2 nuts securing front pipe to
intermediate pipe/silencer.
6.Remove 6 nuts securing front pipe to exhaust
manifolds.
7.Release front pipe and collect front pipe to
manifold gaskets.
8.With assistance remove front pipe.
9.Remove HO2S from front pipe.
Refit
1.If refitting existing HO2S, apply anti-seize
compound to HO2S threads.
NOTE: A new HO2 sensor is supplied pre-
treated with anti-seize compound.
2.Fit HO2S to front pipe and tighten to 45 Nm (33
lbf.ft).
3.Clean front pipe and mating faces.
4.Position front pipe, with new front pipe to
manifold gaskets, and align front pipe with
intermediate pipe/silencer and exhaust
manifolds.
5.Fit and tighten exhaust manifold nuts to 30 Nm
(22 lbf.ft).
6.Fit and tighten intermediate pipe/silencer nuts
to 25 Nm (18 lbf.ft).
7.Fit chassis cross member and tighten bolts to
25 Nm (18 lbf. ft).
8.Connect HO2S multiplugs and secure to
support brackets.
Intermediate pipe/silencer
$% 30.10.11
Remove
1.Raise vehicle on ramp.
2.Remove 2 nuts securing intermediate pipe/
silencer to front pipe.
3.Remove 3 nuts securing intermediate pipe/
silencer to tail pipe.
4.Release intermediate pipe/silencer from
mountings and remove intermediate pipe/
silencer.
5.Collect intermediate pipe/silencer to tail pipe
gasket.
Refit
1.Clean intermediate pipe/silencer, front pipe and
tail pipe mating faces.
2.Position intermediate pipe/silencer and locate
on mountings.
3.Using a new intermediate pipe/silencer to tail
pipe gasket, align intermediate pipe/silencer
with tail pipe and front pipe.
4.Fit nuts to intermediate pipe/silencer and
tighten to 25 Nm (18 lbf.ft).

MANIFOLDS AND EXHAUST SYSTEMS - V8
REPAIRS 30-2-9
Tail pipe
$% 30.10.22
Remove
1.Raise vehicle on ramp.
2.Remove 3 nuts securing intermediate pipe/
silencer to tail pipe.
3.Release and remove tail pipe from mounting.
4.Collect intermediate pipe/silencer to tail pipe
gasket.
Refit
1.Clean silencer and tail pipe mating faces.
2.Position tail pipe and secure on mounting.
3.Using a new gasket, align tail pipe to
intermediate pipe/silencer.
4.Fit nuts to intermediate pipe/silencer and
tighten to 25 Nm (18 lbf.ft).
Heat shield - brake servo - Without
Secondary Air Injection
$% 30.10.48
Remove
1.Release fixings and remove battery cover.
2.Disconnect battery earth lead.
3.Remove nut securing heat shield bracket to
valance.
4.Remove 2 bolts securing heat shield and
remove heat shield.
Refit
1.Fit heat shield, tightening bolts to 25 Nm (18
lbf.ft) and nut to 10 Nm (7 lbf.ft).
2.Connect battery earth lead.
3.Fit battery cover and secure with fixings.

MANIFOLDS AND EXHAUST SYSTEMS - V8
30-2-10 REPAIRS
Heat shield - brake servo - With
Secondary Air Injection
$% 30.10.48
Remove
1.Release fixings and remove battery cover.
2.Disconnect battery earth lead.
3.Remove nut securing heat shield bracket to
valance.
4.Remove 2 bolts securing heat shield and
remove heat shield.
Refit
1.Fit heat shield, tightening bolts to 25 Nm (18
lbf.ft) and nut to 10 Nm (7 lbf.ft).
2.Connect battery earth lead.
3.Fit battery cover and secure with fixings.
Gasket - inlet manifold - lower
$% 30.15.08
Remove
1.Remove both rocker covers.
l

+ ENGINE - V8, REPAIRS, Gasket
- rocker cover - LH.
l

+ ENGINE - V8, REPAIRS, Gasket
- rocker cover - RH.
2.Release and disconnect LH injector harness
and multiplugs.
3.Release 3 clips securing top hose and remove
top hose.
4.Remove auxiliary drive belt.

+ CHARGING AND STARTING,
REPAIRS, Belt - auxiliary drive.

MANIFOLDS AND EXHAUST SYSTEMS - V8
REPAIRS 30-2-11
5.Remove 3 bolts securing ACE pump, release
pump and position aside.
6.Remove 2 bolts securing alternator and
remove alternator. 7.Remove 3 bolts securing PAS pump pulley and
remove pulley.
8.Remove jockey pulley.
9.Position tray to catch spillage, release PAS
pump high pressure pipe.
CAUTION: Always fit plugs to open
connections to prevent contamination.
10.Remove bolt securing oil cooling pipe and
release bracket from auxiliary housing.
11.Remove two bolts securing PAS pump.
12.Remove 5 bolts and one nut securing auxiliary
housing. Pull housing forward, release PAS
pump and remove housing.

MANIFOLDS AND EXHAUST SYSTEMS - V8
30-2-12 REPAIRS
13.Remove 4 bolts securing top hose outlet and
remove outlet pipe.
14.Remove and discard 'O' ring.
15.Position absorbent cloth to catch spillage.
16.Disconnect fuel pipe.
CAUTION: Always fit plugs to open
connections to prevent contamination.17.Using the sequence shown, remove 12 bolts
securing the inlet manifold.
18.Remove inlet manifold.
19.Remove 2 bolts securing inlet manifold gasket
and collect gasket clamps.

MANIFOLDS AND EXHAUST SYSTEMS - V8
REPAIRS 30-2-13
20.Remove inlet manifold gasket.
21.Remove gasket seals.
Refit
1.Clean all traces of sealant from cylinder head
and cylinder block notches.
2.Clean mating faces of cylinder block, cylinder
head and inlet manifold.
3.Apply sealant, Part No. STC 50550 to cylinder
head and cylinder block notches.
4.Fit new gasket seals, ensuring ends engage
correctly in notches.
5.Fit new inlet manifold gasket.
6.Position gasket clamps and fit bolts, but do not
tighten at this stage.
7.Position inlet manifold to engine. Fit manifold
bolts and, working in the sequence shown,
tighten bolts initially to 10 Nm (7 lbf.ft) then to
51 Nm (38 lbf.ft).
8.Tighten gasket clamp bolts to 18 Nm (13 lbf.ft).
9.Connect fuel pipe.
10.Clean top hose outlet pipe mating faces.
11.Fit new 'O' ring to outlet pipe.
12.Position outlet pipe, fit bolts and tighten to 22
Nm (16 lbf.ft).
13.Position alternator, fit bolts and tighten to 45
Nm (33 lbf.ft).
14.Position PAS pump to auxiliary housing and
locate housing on engine. Fit bolts and tighten
to 40 Nm (30 lbf.ft).15.Fit and tighten auxiliary housing nut to 10 Nm (7
lbf.ft).
16.Fit bolts securing PAS pump and tighten to 22
Nm (16 lbf.ft).
17.Position oil cooling pipe bracket fit bolt and
tighten to 22 Nm (16 lbf.ft).
18.Fit and tighten PAS pump high pressure pipe.
19.Position jockey pulley and tighten bolt to 50 Nm
(37 lbf.ft).
20.Clean PAS pump pulley mating faces.
21.Position PAS pump pulley, fit bolts and tighten
to 22 Nm (16 lbf.ft).
22.Clean ACE pump dowels and dowel holes.
23.Position ACE pump, fit bolts and tighten to 22
Nm (16 lbf.ft).
24.Fit auxiliary drive belt.

+ CHARGING AND STARTING,
REPAIRS, Belt - auxiliary drive.
25.Secure injector harness and connect injector
multiplugs.
26.Position top hose and secure clips.
27.Fit rocker covers.
l

+ ENGINE - V8, REPAIRS, Gasket
- rocker cover - LH.
l

+ ENGINE - V8, REPAIRS, Gasket
- rocker cover - RH.
28.Check and top up PAS fluid

MANIFOLDS AND EXHAUST SYSTEMS - V8
30-2-14 REPAIRS
Gasket - exhaust manifold
$% 30.15.12
This procedure is the same for both exhaust manifold
gaskets.
Remove
1.Raise front of vehicle.
WARNING: Do not work on or under a
vehicle supported only by a jack. Always
support the vehicle on safety stands.
2.Remove 3 nuts securing front pipe to exhaust
manifold, release front pipe and collect gasket.3.Remove 8 bolts and spacers securing exhaust
manifold.
4.Remove exhaust manifold.
5.Remove 2 manifold gaskets.
Refit
1.Clean exhaust manifold and cylinder head
mating face.
2.Position exhaust manifold and new gaskets on
cylinder head.
3.Fit spacers and exhaust manifold securing
bolts and, working from the centre outwards,
tighten bolts to 38 Nm. (28 lbf.ft).
4.Clean front pipe and manifold mating faces.
5.Using a new gasket, position front pipe, fit nuts
and tighten to 30 Nm. (22 lbf.ft).
6.Remove stand(s) and lower vehicle.

MANIFOLDS AND EXHAUST SYSTEMS - V8
REPAIRS 30-2-15
Gasket - inlet manifold - upper - Without
Secondary Air Injection
$% 30.15.24
Remove
1.Release fixings and remove battery cover.
2.Disconnect battery earth lead.
3.Remove bonnet.

+ EXTERIOR FITTINGS, REPAIRS,
Bonnet.
4.Release MAF sensor harness from clip.
5.Loosen clips securing air intake hose. Release
and remove air intake hose.
Note: Pre 03 MY air intake hose illustrated.
6.Disconnect throttle and cruise control cables.
Release cables from abutment bracket and
position aside. 7.Disconnect EVAP pipe from inlet plenum.
8.Disconnect multiplug from throttle body.
9.Remove clip securing breather hose to throttle
body and release breather hose.
10.Position a drain tray beneath the engine to
collect coolant.
11.Release clips securing coolant hoses to
throttle body and disconnect hoses.