REV F 4-6 604345
mowers and supplies clean combustion air to the engine. Figure
4-7
These mowers are equipped with a safety filter. The filter
element slides over the safety filter. Figure 4-8
The safety filter does not require servicing unless it becomes
contaminated with dirt or moisture.
Recommended service procedure
1. Release clamps and remove element. Clean the canister
with a damp cloth.
2. Before installing a new element, inspect it by placing a
bright light inside and rotating the element slowly,
looking for any holes or tears in the paper. Also check
gaskets for cuts or tears. Do not attempt to use a damaged
element which will allow abrasive particles to enter the
engine.
3. Reinstall the dust cup. Make sure it seals all the way
around the air cleaner body, then tighten the clamps.
Figure 4-7
4. Check all fittings and clamps periodically for tightness
and inspect hoses for holes or cracks.
5. Periodically check the intake hose for signs of ingested
dust. Locate and repair the source of ingested dirt.
6. Never operate the machine without an air filter installed.
Overservicing
Overservicing occurs when an air filter element is removed
for cleaning or replacement before it is necessary. Each time the
filter is removed a small amount of dirt and dust could fall in the
intake system. This accumulated dirt can cause a dusted engine.
It only takes a few grams of ingested dirt over the normal
service life of an engine to cause a dusted engine.
Do not clean the element, but replace with a new element
only. Cleaning used air filter elements, through improper
cleaning procedures, can get dust on the inside of the filter
causing dirt ingestion and engine failure.
It is important to note that whenever an air filter element is
cleaned by any method, the person or company performing the
cleaning assumes responsibility for the integrity of the filter
from then on. The warranty for air filters expires upon
cleaning or servicing in any manner because the condition of
the filter after servicing is completely out of the filter’s
control. Therefore, on a dust ingested engine failure, there
will be no warranty consideration if the air filter element
has been cleaned or serviced in any manner.
A partially dirty air filter element works better than a new
element. Therefore, a dirty filter element is not bad for the
engine unless it is excessively restricting the air flow and engine
performance is affected. The reason is simple. The media in the
filter must be porous to allow air to pass through it. When dirty
air passes through the filter, the dirt plugs some of the holes in
the media and actually acts as part of the filter media. When the
next round of dirt enters, the first dirt helps filter out even
smaller particles making the filter more efficient at stopping dirt
from entering the engine. This is referred to as barrier filtration.
Of course, at some point the filter media becomes too clogged
to allow air to pass.
The mowing conditions will determine the frequency of air
filter element changing.
Air restriction indicator
These units have an air restriction indicator installed in the air
cleaner. Figure 4-9
Replace the element whenever the restriction indicator
Figure 4-6
Figure 4-7
Pre-cleaner
Canister
Dust cap
Figure 4-8