BENDIX TCH-001-032 Manual Do Utilizador
Technical
Bulletin
Bulletin No: PRO-01-32
Effective Date: 2/1/98
Cancels: PRO-01-32 dated 8/1/88
Page: 1 of 3
Subject:
TROUBLESHOOTING COMPRESSOR OIL PASSING
GENERAL COMMENTS
Some oil carryover from the air compressor into the air brake system occurs as a normal part of all air compressor
operation. It is typical to find some presence of oil at the inlet and discharge ports of the air. Oil present at the
exhaust of drain valves, air dryers or aftercoolers is normal and indicative these components are functioning
properly, removing contaminants from the system.
operation. It is typical to find some presence of oil at the inlet and discharge ports of the air. Oil present at the
exhaust of drain valves, air dryers or aftercoolers is normal and indicative these components are functioning
properly, removing contaminants from the system.
Vehicles equipped with a desiccant type air dryer that incorporates a filter (separator) for removing oil from the
air will normally minimize oil passed through to the reservoir. The oil collects in the air dryer with condensed
moisture and is periodically purged. Often, the routing or location of the air dryer exhaust port can amplify
concerns about oil passing, depending on where the purged oil / water mixture is expelled on the vehicle, e.g. on a
rear fender or onto a fuel tank. This can mistakenly be identified as “problem” oil passing, when in actuality the
air dryer and compressor are functioning as intended.
air will normally minimize oil passed through to the reservoir. The oil collects in the air dryer with condensed
moisture and is periodically purged. Often, the routing or location of the air dryer exhaust port can amplify
concerns about oil passing, depending on where the purged oil / water mixture is expelled on the vehicle, e.g. on a
rear fender or onto a fuel tank. This can mistakenly be identified as “problem” oil passing, when in actuality the
air dryer and compressor are functioning as intended.
Oil Passing & Air Dryers
If excessive oil is passing from the air compressor, the air dryer filter element and desiccant may become
saturated. One of the first signs of an oil saturated filter element or desiccant cartridge is moisture appearing in
the reservoirs. In this case, the air dryer filter element and desiccant need to be serviced and the reason for
excessive water and oil must be determined.
saturated. One of the first signs of an oil saturated filter element or desiccant cartridge is moisture appearing in
the reservoirs. In this case, the air dryer filter element and desiccant need to be serviced and the reason for
excessive water and oil must be determined.
Areas that should be explored are:
* Frequency of reservoir draining.
* Length of time in service; i.e. age of the compressor and desiccant cartridge.
* Brake system maintenance, particularly the leakage of air from the vehicle system.
* Vehicle accessories which may cause high air usage; i.e. air suspension, air wipers, air starters,
kneeling systems, etc.
* Vehicle vocations that may cause high air usage.
* Length of time in service; i.e. age of the compressor and desiccant cartridge.
* Brake system maintenance, particularly the leakage of air from the vehicle system.
* Vehicle accessories which may cause high air usage; i.e. air suspension, air wipers, air starters,
kneeling systems, etc.
* Vehicle vocations that may cause high air usage.
Vehicles may be equipped with condensing type aftercoolers or drain valves instead of an air dryer. These devices
have little or no effect on preventing oil or water from being passed through the system and into the reservoir.
have little or no effect on preventing oil or water from being passed through the system and into the reservoir.