Cummins/Onan — Siphon Break Installation
Installation · Siphon break (anti-siphon)
From a Cummins/Onan service manual covering: 2.5A, 2.5L, 2.7 AJ, 4.0CCK, 6.0CCKB, 6.5 NH, JC - 3CR / 96 T. Check it applies to your exact model before use.
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Before you start
- Be sure the slotted opening in the vacuum relief valve is open to atmospheric pressure.
Procedure
- Locate and hang siphon break vertically within 5 feet (1.5 m) of the exhaust water injection elbow and 12 inches (305 mm) or more above the load waterline.
- Disconnect exhaust water (raw) discharge hose at the exhaust water injection elbow.
- Connect exhaust water discharge hose between engine water outlet and siphon break inlet elbow.
- Connect hose between siphon break outlet elbow and exhaust water injection elbow; tighten all hose clamps.
Tools required
- Pipe straps Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Mount at least 12 inches (305 mm) above load waterline
- Within 5 feet (1.5 m) of exhaust water injection elbow
Source: Cummins/Onan service 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.