FITMENT
- 2003-2007 Dodge Ram Cummins 5.9L (Only Manual Transmission!).
- 2007.5-2018 Dodge Ram Cummins 6.7L (Manual & Automatic Transmissions.).
DESCRIPTION
Product Overview
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Stagnant coolant flow at the rear of the engine block is a silent killer on 2003–2018 5.9L and 6.7L Cummins diesels. The factory cooling system starves cylinder #6 of adequate circulation, allowing coolant to boil and build dangerous thermal pressure—frequently resulting in blown head gaskets, cracked cylinder heads, and dropped valve seats.
- This Coolant Bypass Upgrade addresses this critical OEM design flaw by creating a secondary flow path at the rear of the block. By continually venting trapped heat and pressure back to the cooling system, it keeps rear cylinder temperatures stable, protects critical head gasket seals, and ensures bulletproof reliability for heavily loaded or high-horsepower Cummins builds.
Key Features
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Prevent blown head gaskets, cracked blocks, and dropped valve seats caused by localized overheating at the back of the engine.
- Lean on a built-in inline thermostat that only opens when the rear cylinders demand additional cooling, preserving fast cab heat in freezing conditions.
- Trust leak-free, vibration-proof AN O-ring fittings paired with a durable braided hose that handles high-pressure coolant spikes without failure.
- Rely on materials that hold up: high-quality aluminum fittings, braided stainless hose, and robust metal and polyester construction throughout.
FAQ
Q: Will this kit work on my automatic transmission truck?
A: It depends on your model year. For 2003–2007 5.9L Cummins engines, this kit fits manual transmission trucks only due to tight clearance around the early automatic bellhousing. For 2007.5–2018 6.7L engines, it’s fully compatible with both manual and automatic transmissions.
Q: Why does a Cummins engine even need an external bypass line?
A: The factory cooling circuit pumps coolant front-to-back, and the flow weakens so much by cylinder 6 that coolant effectively boils in place. This bypass kit creates a continuous, high-flow cooling loop to end that dangerous stagnation behind the block.
Q: Will running this bypass kit in winter cause my cab heater to take forever to warm up?
A: No. Unlike cheap unregulated bypass hoses that stay wide open 24/7, this kit features a thermostatically controlled valve. It remains closed during cold starts and only opens when the rear block temperature rises, so your heater gets hot fast on freezing mornings.
Q: Do I need a tuner or ECU flash after installing this?
A: No — this is purely a mechanical cooling upgrade. It doesn’t interact with emissions sensors or factory engine electronics, so it will never trigger a check engine light or fault code.
