278681R | Genuine Bendix® Tu-Flo 500 Air Compressor

1. Compatible Engine Platforms

The specification is commonly mounted on classic and heavy-duty diesel engines, including:

• Cummins®: Big Cam, Small Cam, N14, N855, PT series, and L10/M11 engines (flange or belt/gear-driven mounting depending on housing configuration).

• Detroit Diesel®: 2-Stroke Series (6V71, 8V71, 6V92, 8V92) and early Series 60 engines.

• Caterpillar®: 3406A, 3406B, 3406C, and 3306 engine series.

• Mack® & International®/Navistar®: Classic Mack E6/E7 and International DT466 / MaxxForce/Navistar V8 platforms.

2. Compatible Vehicle Makes & Models

Used across a wide range of Class 7 & 8 commercial trucks, buses, and vocational machinery:

• Freightliner: FLD, Classic, Century Class.

• Kenworth: W900, T600, T800, K100.

• Peterbilt: 379, 359, 378, 357.

• International / Navistar: 4000, 8000, 9000-series heavy trucks and Paystar models.

• Mack Trucks: R-Series, CH, CL, Granby series.

• Buses & Coaches: MCI, Prevost, Gillig, and Blue Bird transit/school buses.

1. What is it?

Part is the heart of a heavy vehicle's compressed air system. Driven by the vehicle's engine (via gears or belts), it draws ambient air, compresses it, and feeds high-pressure air into the primary and secondary air reservoirs to power critical pneumatic systems.

2. Core Functions & Applications

• Air Brake System Supply: Generates the continuous air pressure required to operate pneumatic service brakes, spring parking brakes, and trailer brake systems.

• Auxiliary Pneumatics: Supplies compressed air for air suspension systems, air horns, cab air seats, and automated transmission shifters.

• Cooling & Lubrication Integration: Utilizes an engine coolant-cooled cylinder head to prevent oil carbonization and is lubricated directly by the engine's oil system.

1. Excessive Oil Carryover into Air Tanks

Worn piston rings or scored cylinder walls allow engine oil to bypass the compressor pistons into the air system:

• Symptom: Liquid oil or sludge discharging from the air dryer purge valve or draining out of the primary air tanks.

• Consequence: Contaminates brake valves, degrades rubber diaphragms in brake chambers, and clogs the air dryer desiccant cartridge.

2. Slow Air Pressure Build-Up (Low CFM Delivery)

As internal valves or piston rings wear, the compressor loses efficiency and struggles to pump air:

• Symptom: Taking significantly longer than standard time (typically >3–5 minutes) to build pressure from 85 PSI to 100+ PSI at high idle.

• Consequence: Triggers low-air warning buzzers and dashboard lights; delays vehicle departure.

3. Excessive Noise & Knocking

Worn connecting rod bearings, wrist pins, or excessive crankshaft end-play create mechanical knocking noises:

• Symptom: Loud clattering or rhythmic metallic knocking coming from the front/side of the engine where the compressor is mounted.

4. Coolant Leaks / Overheating Air System

A blown head gasket or cracked cylinder head on the Tu-Flo 500 can cross-contaminate cooling and air passages:

• Symptom: Coolant disappearing with no external leaks, white milky residue in air tanks, or air bubbling into the radiator/expansion tank.

• Consequence: Engine overheating or severe carbon build-up in the discharge line due to extreme compressed air temperatures.

5. Air Leaks & Failure to Unload

If the internal unloader valve mechanism sticks or fails:

• Symptom: The compressor continuously pumps air past the governor setpoint (causing air safety pop-off valves to trigger) OR fails to pump air at all because the unloader remains stuck open.