The following example is a 2002 Orion® Series 50


This guide will take you through the installation of an oil/carbon separator system for Orion® buses with series 50 engines.  The oil/carbon separator system will prevent contamination of the air system by oil migrating from the Bendix® TU-750 air compressor.
Shut front door air valve off in driver's compartment and open defroster compartment door.
Disconnect drain tube from bottom of filter.  Disconnect the inlet and outlet air hoses from filter fittings.  Remove the two bolts and mounting brackets, saving them for later use.  Discard the removed unit.
Remove the pre-assembled front door water/oil vapor separator unit from the box.  Place the two previously removed P-clamps on the water filter and install the complete assembly with the water filter towards the door.  The air flow is from right to left.  Note that the assembly has arrows on top of each filter unit.

secure the complete unit to the original mounting bracket using original nuts and bolts.  From the parts bag, select a straight tubing fitting; 1/4" tube by 1/8" male npt.  Screw the fitting into the knurled knob.  Attach the water filter drain hose to the new fitting. 

Trim 1/8" from the end of the inlet and outlet airlines.  Install the provided brass inserts into inlet and outlet air lines.  Attach the inlet and outlet hoses.  Make sure that the fit is secure.

Place one of the provided yellow decals as shown in the photo.

Leave the door open, we will be testing for leaks at completion.

Move to the rear door access panel.

Open the panel.

Locate the water filter and remove it. 

Save the mounting brackets for re-use.

Take the oil/carbon filter from the box and remove the mounting bracket, it will not be used here.  Also remove the right angle fitting and replace it with a straight fitting provided.

Cut 1/8" off from each line.  Insert the brass eyelets in the inlet and outlet tube.

Attach the new oil/carbon filter to the same location the water filter was using the same p-clamps.

Attach the tubing to the oil/carbon filter.

Install one of the provided decals as shown in the photo.

Leave the access door open, we will be testing for leaks at completion.

Open the curb side engine compartment access door.
Locate the tee fitting shown in the photo.

Remove the quick disconnect on top of the tee.

Save the quick disconnect for re-use.

Remove the copper line from the tee fitting.

Remove the tee fitting.

Take a look at the bulk-head fitting...

The black material shown in the photo is an oil/carbon mixture.

The filter you are installing will prevent this from happening!

Install the two 3/4" street elbows on the bulk-head thread as shown.
Disassemble the filter and attach the filter head to the street elbow.

The filter head is stamped on one side with the word "IN".  Make sure that this word is on your left.  The decal on the filter head should face you.


Attach the threaded rod to the filter head as shown.

Attach the filter element and baffle as shown. 

NOTE:  The filter element will only fit in one direction.

The ID on top and bottom are different.

Take a look at the design of the element:  It not only contains

a metal screen on the outside, but also has one on the inside.

This heavy duty element is build to last!


Check the O-Ring on the bowl, making sure it is in proper position.

Carefully screw on the metal bowl to the filter head.

Move it into a vertical position.

Install the quick disconnect, copper tubing fitting and safety relief valve as shown in the photo and attach to the filter inlet.

Cut the tubing as shown in the photo.

Connect the tubing to the fitting.  Remember to use a new ferrule.

Note:  A new ferrule is provided for you in the kit!

Check your work.

Affix the last decal to the engine compartment door.

The installation should look like this.


Note:  The oil/carbon/air/water mixture will enter the filter from the left.  The carbon will become trapped inside of the element as the oil/water and air mixture pass through. 

The oil will fall into the collection bowl as the air and water mixture go on to the (now protected) air dryer.

Since the air dryer will not be exposed to oil and carbon, it can do a much better job removing the water.

As a bonus, the temperature of the mixture will cool about 50° as it passes through the filter!  This enables the air dryer to remove even more water.

Check your work, and power up the bus to check all three work areas for air leaks. 

Think you can benefit from the above?

We look forward to speaking with you.

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