BENDIX 360CC, Manual

A-14

Tests

Exterior leaks at the head gasket are not a sign that oil is being passed into 
the air charging system.  Oil weepage at the head gasket does not prevent 
the compressor from building air.  

Observe the amount of weepage from the head gasket.  

If the oil is only around the cylinder head area, it is acceptable (return the vehicle 
to service), but, if the oil weepage extends down to the nameplate area of the 
compressor, the gasket can be replaced.  

Test 1:  Excessive Oil Leakage at the 
Head Gasket 

Inspect for air leaks when working on a vehicle and 
repair them promptly.  
Park the vehicle on level ground and chock wheels.  
Build system pressure to governor cut-out and allow 
the pressure to stabilize for one minute.  

Step 1: 

Observe the dash gauges for two additional 

minutes without the service brakes applied.  

Step 2:

 Apply the service brakes and allow the 

pressure to stabilize.  Continue holding for two 
minutes (you may use a block of wood to hold the 

pedal in position.) Observe the dash gauges.
If you see 

any noticeable decrease

 of the dash air 

gauge readings (i.e.  more than 4 psi, plus two psi 
for each additional trailer) during either two minute 
test, 

repair the leaks

 and repeat this test to confi rm 

that they have been repaired.
Air leaks can also be found in the charging system, 
parking brakes, and/or other components - inspect 
and repair as necessary.

Test 2:  Air Brake System and Accessory Leakage

Caution: The temperatures used in this test 
are not normal vehicle conditions.
Above normal temperatures can cause oil (as 
vapor) to pass through the air dryer into the 
air brake system.  

This test is run with the engine at normal operating 
temperature, with engine at max. rpm.  If available, 
a dyno may be used.
1.  Allow the compressor to build the air system 

pressure to governor cut-in.  

2.  Pump the brakes to bring the dash gauge 

pressure to 90 psi.

3.  Allow the compressor to build pressure from 

95 to 105 psi gauge pressure and maintain 
this pressure range by cycling the brakes

 for 

fi ve (5) minutes.  

4.  Then, while maintaining max rpm and 

pressure range, measure and 

record the 

surface temperature 

of the

 fi ttings

:

 

at the compressor discharge port.  (T1).

 

at the air dryer inlet fi tting.  (T2).

Use a touch probe thermocouple for measuring 
the temperature.

5.  See table below.
6.  Re-test before returning the vehicle to service.

Test 3:  Air Compressor Discharge 
Temperature and Air Dryer Inlet 
Temperature*

Compressor Air 

Dryer 

 Discharge 

Inlet 

 Fitting 

Fitting

Action

under  

under 

Temperatures are within 

360°F 

200°F 

normal range for this test, check 

other symptoms.  Go to 4.0 (h). 

under 

over 

This could indicate a discharge 

360°F 

200°F 

line problem (e.g.  restriction).  

  Call 

1-800-AIR-BRAKE

  (1-800-247-2725) 

and speak with our Tech Team.  

over 

__ 

Compressor is running hot.

360°F 

Check coolant 4(f) and/or 

discharge line 4(g). 

T1 T2 

(* Note that only vehicles that have passed Test 2 
would be candidates for this test.)

Discharge Line

T1

T2

Look

for

Weepage