← Coolant loss on all engines
Symptoms · 6.7 Cummins 2007-2018
6.7 Cummins 2007-2018: losing coolant
3 documented failures on this engine list this among their signs. They are ordered from the most widespread down. Each one shows the signs in its record's own words, how to tell it from the others, the usual fix and any recall or bulletin.
Not sure which engine you have, or want the recalls for your exact truck? Check your VIN: it names the engine and lists the campaigns for that model year. Whether a recall is still open on your VIN: nhtsa.gov/recalls.
verified
How widespread: Common
30 NHTSA owner complaints match it, out of 1,355 checked
How it shows up
- coolant weep from the weep hole / front cover area
- coolant smell, occasional low-coolant warnings
Its other signs
- bearing noise from the front of the engine; overheating if run low
How to tell it apart
- trace the leak to the weep hole with a UV dye / clean-and-observe
- spin/listen for bearing play at service intervals
- check coolant condition and service history - abrasive coolant tells you the replacement needs a flush too
Usual fix
replace the water pump; flush and refill with spec coolant while open
Root cause, parts and sources →
verified
How widespread: Common
6 NHTSA owner complaints match it, out of 1,355 checked
How it shows up
- white sweet-smelling smoke, coolant loss with no external leak
- EGR cooler DTCs / flow codes; coolant smell at the exhaust
- pressurised cooling system (bubbles at the degas bottle)
Its other signs
- in bad cases: hydro-lock symptoms / white smoke clouds at startup
How to tell it apart
- block-test the coolant for combustion gas (careful: EGR cooler gas also shows)
- compare EGR cooler temp vs coolant temp PIDs at startup (should track until warm-up completes)
- pressurise the cooling system and watch for immediate pressure rise through the EGR side
Usual fix
replace the EGR cooler with the correct-era unit (2007.5-2009 vs 2010+ are different hardware); flush and refill with spec coolant
Recalls and bulletins
TSB 18-045-15 REV ATSB 18-045-15TSB 18-018-13 REV. ATSB 18-005-13
Root cause, parts and sources →
verified
How widespread: Rare
3 NHTSA owner complaints match it, out of 1,355 checked
How it shows up
- coolant loss, combustion gas in the cooling system, pressurised degas bottle
Its other signs
- white smoke, sweet smell; overheating events in history
- misfire on startup after sitting (fluid into a cylinder)
How to tell it apart
- block-test the coolant for combustion gas
- monitor cooling-system pressure rise vs RPM (combustion leak signature)
- compression / cylinder leak-down if a specific hole is suspected
Usual fix
fix the overheat cause first (fan clutch, coolant leak, DPF derate ignored) or the new gasket dies too
Root cause, parts and sources →
Other symptoms on the 6.7 Cummins 2007-2018
Hard start, long crank or no-startLoss of power, limp mode or derateWhite smoke from the exhaustOverheating or temperature creeping upOil leak, oil consumption or rising oil levelTicking, knocking, rattle or whineMisfire, rough idle, hesitation or surgingDEF, DPF and regeneration warnings
Everything on the 6.7 Cummins 2007-2018Its recalls and bulletins