- Guardian Liquid-Cooled, Prepackaged Standby Generator Owner's Manual

1.10 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.
1.11 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 quali-
ty 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 radia-
tor, recovery 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 poisonous to them.
Do not use any chromate base rust inhibitor
with ethylene glycol base antifreeze, or chromi-
um hydroxide (“green slime”) will form and
cause overheating. Engines that have been oper-
ated 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 equip-
ment.
1.12 EMISSIONS CONTROL SYSTEM
(MODELS 0046262, 0046263 & 0046264)
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 spe-
cific requirements.
Figure 1.4 - Emissions Control System
1.12.1 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 cat-
alytic muffler (closer to the engine), continuously moni-
tors the exhaust gas composition. A feedback signal is
sent from the oxygen sensor to the air fuel ratio con-
troller, which controls the fuel system to maintain the
optimal, stoichiometric air fuel ratio. The air fuel mix-
ture 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 con-
troller determines the amount of vacuum signal sent to
the fuel regulator. The more vacuum sent to the regula-
tor, 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