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1.9 ENGINE OIL RECOMMENDATIONS
The unit has been filled with 15W-40 engine oil at the
factory. Use a high-quality detergent oil classified “For
Service CC, SD, SE or SF.” Detergent oils keep the
engine cleaner and reduce carbon deposits. Use oil hav-
ing the following SAE viscosity rating, based on the
ambient temperature range anticipated before the next
oil change:
Any attempt to crank or start the engine before it
has been properly serviced with the recommended
oil may result in an engine failure.
1.10 COOLANT
Use a mixture of half low silicate, ethylene glycol base
antifreeze and half soft water. Use only soft water and
only low silicate antifreeze. If desired, add a high qual-
ity rust inhibitor to the recommended coolant mixture.
When adding coolant, always add the recommended 50-
50 mixture.
Do not remove the radiator pressure cap while the
engine is hot or serious burns from boiling liquid or
steam could result.
Ethylene glycol base antifreeze is poisonous. Do not
use mouth to siphon coolant from the radiator, recov-
ery bottle or any container. Wash hands thoroughly
after handling. Never store used antifreeze in an
open container because animals are atracted to the
smell and taste of antifreeze even though it is poison-
ous to them.
Do not use any chromate base rust inhibitor with eth-
ylene glycol base antifreeze, or chromium hydroxide
(“green slime”) will form and cause overheating.
Engines that have been operated with a chromate
base rust inhibitor must be chemically cleaned before
adding ethylene glycol base antifreeze. Using any
high silicate antifreeze boosters or additives also will
cause overheating. Generac also
recommends that any soluble oil inhibitor NOT be
used for this equipment.
1.11 EMISSIONS CONTROL SYSTEM
(Model 004626-0)
This model is equipped with an active exhaust emis-
sions control system to comply with certain California
air district regulations for natural gas emergency gener-
ating sets, including the South Coast Air Quality
Management District. Do not tamper with or disable
any part of this system, including the exhaust catalyst,
carburetor, oxygen sensor, air-fuel ratio controller, sole-
noid valve and gas regulator. These items are not sub-
ject to periodic maintenance or adjustment.
This model is of a size (greater than 50 brakehorse-
power) that may require a review by air permitting
authorities prior to installation and operation. Consult
the local air management district for details and specif-
ic requirements.
Figure 1.3 - Emissions Control System
AIR FUEL RATIO CONTROLLER
The air fuel ratio controller is an advanced micro-
processor designed to work with a three-way catalyst
and a feedback (rich bias) carburetor to provide close-
loop fuel management. Its digital adaptive control is
able to compensate for variations in fuel mixtures and
engine tunes. It is time based activated. (For example, it
will activate after 45 seconds from receiving the power
signal.) The part number for the air fuel ratio controller
is 0D4221.
Principle of Operation: The oxygen sensor, installed on
the exhaust pipe, between the engine and the catalytic
muffler (closer to the engine), continuously monitors
the exhaust gas composition. A feedback signal is sent
from the oxygen sensor to the air fuel ratio controller,
which controls the fuel system to maintain the optimal,
stoichiometric air fuel ratio. The air fuel mixture to the
engine is controlled by biasing the diaphragm in the fuel
regulator using vacuum (from the carburetor). This
vacuum signal is directed to the fuel regulator via the
control valve. The air fuel ratio controller determines
the amount of vacuum signal sent to the fuel regulator.
The more vacuum sent to the regulator, the more
restricted the fuel flow will be, therefore the leaner the
air fuel mixture.
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Section 1 — General Information
Guardian Liquid-cooled 40 kW Generator
Generac
®
Power Systems, Inc. 7
Temperature Oil Grade(Recommended)
Above 80º F (27º C) SAE 30W or 15W-40
32º to 80º F (-1º C to 27º C) SAE 20W-20 or 15W-40
Below 32º F (0º C) SAE 10W or 15W-40