Cummins/Onan — Charge-Air Cooler Leak Test
Testing & diagnosis
From a Cummins/Onan owner's manual covering: B3.9, B4.5, B5.9. Check it applies to your exact model before use.
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Before you start
- Secure safety chains on the test plugs to any convenient capscrew on the radiator assembly; this test must not be performed without securely fastened safety chains.
Procedure
- Remove the inlet and outlet hoses from the cooler.
- Install a plug or cap over the outlet side of the cooler.
- Install a pressure gauge and a regulated shop air supply line with a shutoff valve to the inlet side.
- Apply air pressure until the pressure gauge reads a steady 207 kPa [30 psi].
- Shut off the airflow and start a stopwatch; record the leakage at 15 seconds.
- If the pressure drop is 34 kPa [5 psi] or less in 15 seconds, the cooler is operational.
- If greater, check all connections with soapy water and repair or replace as necessary.
Tools required
- Pressure gauge and regulated shop air supply Amazon
- Spray bottle with soapy water Amazon
- Stopwatch Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Test pressure 207 kPa [30 psi]
- Acceptable pressure drop 34 kPa [5 psi] or less in 15 seconds
Source: Cummins/Onan owner's manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.