low oil pressure MERCEDES-BENZ ML430 1997 Complete Service Manual

2
The fresh air openings, the windshield and the
front fenders must be generously masked off
before cleaning and preserving.
be determined by each workshop itself.
Masking is necessary in order to ensure that
no materials whatsoever, e.g. cold cleaning
solvent, wax or similar, penetrate inside the
car (difficult to clean).

3
The screw joint holding the brake fluid
reservoir must be masked off with adhesive
tape, which is to be removed again after
preservation of the engine compartment.

4
Mask off the ventilation hole for the
diaphragm chamber in the pressure control
valve in the cylinder head cover.
Engines 601, 602, 603
AP01.00-
P-8503-
01A
5
Cleaning is to be performed when the engine
is no hotter than hand-hot (at the exhaust)
using a demulsifying cold cleaning solvent
(short action time) and a high-pressure hot-
water cleaner, depending on how dirty the
engine is.
"Demulsifying" means that a mixture of oils
and greases in water separated in the oil
separator pipe.

6
When cleaning the component compartment
behind the engine compartment: Spray only as
much water as necessary under very low
pressure.Electronic control modul es must be covered
beforehand; any that become wet must be
dried afterwards.

7After washing/preserving the engineLubricate throttle cont rol linkage and check
for ease of movement and wear.
8
Preservation is to be performed only when the
engine compartment is dry and using properly
functioning commercially available
equipment.Only use approved wax preservation agents.
Airless devices produce the least
contamination.

9Do not spray the follow ing with preservation
wax:Electrical and electroni c components, belt
drive (belts and pulleys), exhaust pipe and
muffler in component compartment.


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CHECK ALL VISIBLE PARTS FOR SIGNS OF LEAKS AND DAMAGE - AP00.20-P-0053GH
MODEL 163.113 /128 /136 /154 /157 /172 /174 /175
INSPECTING CHASSIS AND LOAD-BEARING BODY PARTS FOR DAMAGE AND CORROSION - AP00.20-P-0090GH
MODEL 163
with Code Z04/Z07
Model 230AP00.20-P-0001L
Model 414AP00.20-L-0001A
Taxi serviceModels 202, 210AP00.20-P-0007A
Model 203AP00.20-P-0007C
Remove
Detach lower engine
compartment panelingModels 163.172/174/175AR61.20-P-1105GH
Remove noise
encapsulationModel 163.113/128AR94.30-P-5400GH
Check

2If traces of fluid are noted
(e.g. oil), then determine
and correct the cause (on a
separate work order).
Check for leaksEngine:
Transmission
Transfer case
Front axle
Rear axle
Pressure oil pump
3Check for leaks and fixingShock absorbers,
suspension struts
4Inspect for leaks and
conditionRubber boots of front axle
shafts
5Inspect lines and hoses for
leaks and condition, pay
attention to chafing points
and routingRadiator
Fuel system
Exhaust system
Clutch actuation
Automatic transmission
Power steering
Brake system
Install
Install lower engine
compartment paneling.Models 163.172/174/175AR61.20-P-1105GH
Install noise encapsulationModel 163.113/128AR94.30-P-5400GH
1Visual inspectionControl arm mountings and
control arms of front axle

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procedure or when
working near engine
5Start engine Allow to run at idle
speed until oil pressure is
displayed.
6Check refrigerant level of
air conditioning systemModel 129 up to 31.5.96
with automatic air
conditioning, code 581a,AP83.30-P-8312DA
Model 140 up to 31.5.95
with automatic air
conditioning, code 581a
with rear air conditioner,
code 582,
Model 202 up to 30.9.95
with automatic air
conditioning, code 581a,
Models 129, 170, 202,
208, 210, 220 with air
conditioning (or
Tempmatic for USA),
code 580
Models 461, 463 with air
conditioning, code H02AP83.30-P-8312G
7Move the pull switch of
the hydropneumatic
suspension into position N
and allow the engine to
run at increased idle speed
until the vehicle has
reached its normal levelOnly for Hydropneumatic
suspension with automatic
level lowering device and
controlled damping, code
215c, All-round
hydropneumatic
suspension, code 487
8Brake testing on test standModel 129, 140, 170, 202,
203, 208, 209, 210, 215,
220AP42.00-P-4290BA
Models 461, 463AP42.00-P-4290G
9Check brake disks for
signs of corrosion. For vehicles which
were parked for more than
6 months.
10Replace brake fluid For vehicles which
were parked for more than
6 months.
Model 140 as of 1.7.93
except code 471AP42.00-P-4280BA
Model 170 except code
471
Model 202 up to 31.5.94
except code 471

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1. Hypoid gear oils
Hypoid gear oils contain a high level of EP/AW additives (Extreme Pressure/Antiwear) and a highly
viscous base oil to prevent seizure when the hypoid gears mesh (mixed and boundary friction conditions)
and to ensure a high degree of protection against wear. The compatibility with radial shaft seals is
regarded as critical with such high concentrations of additives because the P/S additive systems become
thermally unstable at temperatures from 130°C to 140°C and this may lead to sludging of the hypoid oil.
The resultant deposits on the radial shaft seals then generally lead to thermal overload and this in turn
leads to leakage in this component.
The tooth engagement conditions of the hypoid gears result in a high proportion of sliding and a low
hydrodynamic proportion of tooth engagement between the pinion and ring gear. Due to the high
tribological load compared to adhesive wear (seizure) and pitting, the performance of hypoid gear oils
must be particularly high with respect to these types of wear. The formula of the oils is therefore
determined by a high concentration of EP/AW additives and a highly viscous base oil. Alternative oils,
e.g. engine oils, cannot be used for these drive types. Proof of performance that an oil fulfills the
requirements of DaimlerChrysler AG is provided by internal tests. However, the hypoid gear oils must at
least correspond to the US military specification MIL-L-2105 B/C/D and must be classed GL-5 in the
quality grade according to API (American Institute of Petroleum).
1.7 Viscosity requirements
The cold flow behavior is only specified for SAE, ... oils. Here, the limits apply according to SAE J 306
c, according to which the dynamic viscosity may be max. 150,000 mPas at -40°C for oils and at -12°C for
oils. As a result of the tendency to form deposits in the transmission, the polymer content is limited to
max.
1 percent by weight for pour point reducers. Polymers as VI improvers for thickening low-viscosity base
oils are not permitted. The kinematic viscosity at 100°C must be at least 16.5 mm
2 /s.
2. Transmission oils, sheet 235.1
The additive and viscosity properties of the transmission oils are adjusted so that they meet all the
requirements placed on manual transmissions with steel/molybdenum synchronization, spur gear axles,
MB and ZF transfer cases and reversing gears. Among other things, this results in the fact that the oils
ensure a defined friction coefficient of the synchronizer elements, even after a high number of shift
operations, without crunching noises.
With gear drives and roller bearings, the adhesive wear (seizure) and pitting in particular should be
minimized as far as possible.
2.1 Viscosity requirements
The cold flow behavior is only specified for SAE, 80W, ...oils. Here, the limits according to SAE J 306 c
apply, according to which the dynamic viscosity may be max. 150,000 mPas at -40°C for oils, at -26°C
for oils and at -12°C for oils. Due to the formation of deposits in the transmission, the polymer content is
limited to max. 1 percent b
y weight for pour point reducers. Polymers as VI improvers for thickening

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etc. of these coolant specifications also apply. It is imperative that the correct concentration (50/50) is
used in their application and, of course, further dilution is not permitted!
Approval status:
Coolants for all vehicle and engines (Basis 325.0) Sheet 326.0
Coolants for commercial vehicle and industrial engines (Basis 325.2) Sheet 326.2
Coolants for commercial vehicle and industrial engines (Basis 325.3) Sheet 326.3
The regulations for each respective Sheet 325.x are to be transferred correspondingly to Sheet
326.x.
At the time of compiling these regulations it is possible that not all the Sheets 326.x are represented with
approved products.
2.Coolant additives (General information)
Normally, coolant consists of water and anticorrosion/antifreeze agents. The anticorrosion/antifreeze
agents (ethylene glycol with corrosions inhibitors) in the cooling system have to fulfill, among other
things, the following functions:
to provide sufficient corrosion and cavitation protection for all cooling system components
freezing point depression (antifreeze)
increasing boiling point
For corrosion protection purposes the coolant
approx. 50 vol.-% Anticorrosion/antifreeze agents are added if the expected ambient temperatures do not
require an even higher concentration. This concentration (50 vol %) offers frost protection up to approx. -
37°C. A higher concentration is only necessary if the ambient temperatures are even lower.
Even with extremely low ambient temperatures, not more than 55 vol.-% anticorrosion/antifreeze agent
should be used, because at this level the maximum antifreeze protection is reached and a greater
concentration reduces the antifreeze protection again and decreases the heat dissipation (55 vol.-%
corresponds to antifreeze protection down to approx. -45°C).
Should these coolant regulations fail to be observed then corrosion and damage to the cooling
system are inevitable.
The admixture of anticorrosion/antifreeze agent serves to increase the boiling point. By raising the
pressure the boiling temperature can be increased yet further. Both physical relationships are put to use in
modern cooling systems - the maximum coolant temperature is raised, without increasing the danger of
boiling. In keeping with the higher temperature level the cooling performance is also greater. Only
approved products (Sheet 325.0/326.0 or 325.2 or 326.2, 325.3 or 326.3 as well as 312.0 or 311.0)

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GENERAL BRAKE FLUID - BB00.40-P-0330-01A
These specifications are valid for the Mercedes-Benz and smart brands.
General
The brake fluid in the brake system and in the hydraulic clutch operating system fulfills hydraulic tasks. Due to
the high heat build-up during braking, these tasks can only be fulfilled by brake fluids which comply with all of
today's technical requirements in terms of their various properties (viscosity-temperature-characteristic, boiling
point, corrosion protection, oxidation resistance, etc.).
The most important properties which a brake fluid must exhibit are:
High boiling point, to ensure that the brake fluid does not form vapor locks at high temperatures. Vapor
locks reduce the operating pressure and thus the braking effect and may ultimately lead to brake failure.
The boiling point should remain as constant as possible throughout the duration of use of the coolant and
not drop under varying atmospheric influences or operating conditions (pressure, temperature), i.e. the
"wet boiling point" should be as high as possible.
Low compressibility, in particular at high temperatures.
The low-temperature characteristic of the fluid - even when at 40°C - must permit operation, i.e.
primarily, the viscosity must not become too high in the cold.
Compatibility with the materials used in the brake units and clutch operating systems, e.g. the rubber
boots or any other seal materials (elastomers) included in the brake components may only swell to a
controlled extent, any shrinkage must be avoided.
Sufficient corrosion protection for all metals present in the brake system.
The brake fluids released for use in MB vehicle models are listed on Sheet 331.0. These brake fluids not only
comply with our requirements, but also those of the US safety specifications FMVSS 116, DOT 4. The released
"DOT 4 plus" brake fluids (internal designation) are more advanced DOT 4 brake fluids with higher wet boiling
point, standard change interval: 2 years. In order to be able to comply with this useful period without any
problem, we strongly advise the use of released products as per Sheet 331.0, during the warranty phase this is a
precondition for any acceptance of customer claims.
The brake fluid listed on Sheet 331.1 "DOT 4 Type 200" is released for special applications in the UNIMOG
range with more stringent thermal requirements. For this type of use, a brake fluid change interval of 1 year
must be adhered to.
Handling brake fluid
Brake fluid based on polyhydric alcohols in oligomer or polymer form and/or their
Esters are hygroscopic and thus absorbs moisture from the air. Water, however, reduces the boiling point of the
brake fluid, whereby the danger of vapor lock formation is present. Therefore it should be noted that brake fluid
is always stored in sealed vessels. Brake fluid that has been stored unsealed can absorb so much moisture in a
few hours that it is rendered unusable.

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Because the brake fluid also absorbs moisture through the vent bore on the expansion reservoir, the wheel brake
cylinder and the brake hoses, the brake fluid has to be changed for safety reasons at regular intervals, best done
in the spring. When performing this change, make sure that the old fluid is also drained off the clutch system.
Generally, it is vital for the brake/clutch system to be completely drained before being filled with new fluid!
For the above-mentioned reasons, used brake fluid must not be used again.
The brake fluid is amber in color and thus can be easily confused with mineral products.
Therefore, brake fluids should always only be taken from original containers and stored separately from other
mineral oils and fluids.
When performing maintenance operations and repairs on brake parts, make sure that fuel, mineral oil, grease or
suchlike do not enter the brake system. Hydrocarbon-based materials will lead to swelling of the elastomers in
the brake and clutch system and - even in low concentrations - will suffice to cause total failure of the systems.
Only new brake fluid may be used as a rinsing and cleaning agent for the cylinders, lines and the expansion
reservoir of the hydraulic brake system.
Experience shows that before handling brake fluid, the hands must be cleaned and any oil and grease removed.
Brake fluid acts aggressively towards paint and color. In the event of any brake fluid spills or splashes, it must
be rinsed away immediately using copious amounts of water (do not rub it away).
Brake fluid disposal
When disposing of brake fluid, the relevant national specifications must be observed. It is advisable to try to
have the brake fluid disposed of as economic good; this is contingent on
Strict separation of used brake fluid from other materials;
Presence of a disposal channel, which justifies its classification as an economic good, i.e. a proper
alternate usage must be assured.
If this procedure is not possible, used brake fluid is to be disposed of together with any, e.g. paint residue,
solvents and suchlike. Any adding of used oil must be avoided, as it will result in difficulties, if the used oil is to
be recycled; in several countries this is prohibited by the legislators.
MISCELLANEOUS NOTES
NOTES ON SCRAPPING GAS-FILLED HYDRAULIC COMPONENTS - OS00.00-P-1000-01A
all
Unusable gas pressure dampers, spring accumulators, pressure reservoirs and impact absorbers have to be
depressurized before being scrapped according to the respective valid accident prevention regulations. These
safety measures are necessary because gas pressurized hydraulic parts can explode if heat is applied. A risk of
explosion is
given, e.g. when scrapping with cutting torches, smelting or if gas pressurized parts in landfills start

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2000-01 MANUAL A/C-HEATER SYSTEMS
ML 320, ML 430 & ML 55
SPECIFICATIONS
SPECIFICATIONS
DESCRIPTION & OPERATION
A/C CONTROL PANEL
The A/C control panel contains switches to control A/C functions such as blower motor speed, mode control,
i
n-vehicle temperature, A/C on/off, and fresh/recirculated air control. See Fig. 1.
ApplicationSpecification
Compressor TypeNippondenso 7SB16 7-Cyl.
Compressor Belt Tension(1)
Compressor Oil Capacity(2) 5.6-6.3 ozs.
Refrigerant (R-134a) Capacity26.4 ozs.
System Operating Pressures(3)
(1)Belt tension is automatically adjusted by belt tensioner.
(2)Use Densooil 8 (A 001 989 08 03).
(3)Information is not available from manufacturer.
WARNING:To avoid injury from Accidental air bag deployment, read and carefully
follow all SERVICE PRECAUTIONS and DISABLING & ACTIVATING AIR
BAG SYSTEM procedures in AIR BAG SYSTEM SAFETY article in
GENERAL SERVICING.

2001 Mercedes-Benz ML320
2000-01 MANUAL A/C-HEATER SYSTEMS ML 320, ML 430 & ML 55

2001 Mercedes-Benz ML320
2000-01 MANUAL A/C-HEATER SYSTEMS ML 320, ML 430 & ML 55
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A/C housing. Disconnect control module connector. To install reverse removal procedure. Recode 5-digit radio
security code. Using HHT, check for DTC and erase, and set clock.
A/C PUSH BUTTON CONTROL PANEL
Removal & Installation
1. Obtain 5-digit radio security code from vehicle owner. Disconnect negative battery cable. Using radio
removal plates, remove radio. Disconnect electrical connectors.
2. Remove instrument panel center section. Remove 4 A/C control panel screws and remove control panel.
Release pull cables and disconnect connectors. To install, reverse removal procedure. Recode radio. See
RECODING RADIO
under PROGRAMMING.
BLOWER MOTOR
Removal & Installation
Remove passenger-side instrument panel under cover. Remove blower motor mounting screws from A/C
housing unit. Disconnect blower motor connector and remove blower motor. To install, reverse removal
procedure.
COMPRESSOR
Removal & Installation
1. Discharge A/C system, using approved refrigerant recovery/recycling equipment. Remove accessory
drive belt. Disconnect low pressure refrigerant line from compressor. Discard "O" rings. Plug exposed
openings to protect A/C system from debris and moisture.
2. Disconnect high pressure refrigerant line from compressor. Discard "O" rings. Plug exposed openings to
protect A/C system from debris and moisture. Disconnect electrical connector. Remove compressor
mounting bolts.
3. Raise and support vehicle. Remove compressor from under vehicle without spilling refrigerant oil. To
install, reverse removal procedure. Ensure refrigerant oil quantity in compressor is correct. See
COMPRESSOR REFRIGERANT OIL CHECKING under GENERAL SERVICING. Tighten bolts to
specification. See TORQUE SPECIFICATIONS
.
CONDENSER
Removal & Installation
1. Discharge A/C system, using approved refrigerant recovery/recycling equipment. Remove cooling fans.
See COOLING FANS
. Disconnect refrigerant line from receiver-drier. See Fig. 5 . Discard "O" rings.
2. Plug exposed openings to protect A/C system from debris and moisture. Remove refrigerant line from
condenser. Remove radiator upper rubber seal. See Fig. 6
. Remove condenser upper mounting screws.
Lift condenser upward and remove. NOTE: Each time A/C compressor is removed and installed, receiver-drier must be
replaced.

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Diaphragm pressure in the refrigerant compressor control valve (8) (approx. 2 bar)
Suction pressure of refrigerant compressor
The change in suction pressure which is dependent on the control current on the refrigerant compressor control
valve (8) induces a change of pressure in the crankcase (2) and thus a corresponding adjustment of the swash
plate (4).
Automatic air conditioning (AAC [KLA]) OFF
If the automatic air conditioning is regulated or manually switched off, the refrigerant compressor control valve
(8) is completely opened. Refrigerant flows unobstructed over the high pressure side into the crankcase (2). This
in turn leads to a rapid pressure rise in the crankcase (2). The coil body (10), for closing the refrigerant
compressor, is displaced here to the right against the valve plate (9) and thus stops the flow of refrigerant over
the intake side.
Refrigerant compressor lubrication when automatic air conditioning switched off
An internal lubrication circuit ensures the lubrication supply for all moving parts.
Lubrication is ensured at a minimum refrigerant compressor volumetric flow by means of two valves being
regulated. In doing so, the refrigerant is transported together with the compressor oil located in the crankcase
(2) over the bored refrigerant compressor shaft (13). The mixture enters the cylinder housing, where it is
compressed and then pumped into the refrigerant circuit.
REFRIGERANT COMPRESSOR, DESIGN - GF83.55-P-2100-03P

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