← Overheating on all engines
Symptoms · 6.7 Cummins 2007-2018
6.7 Cummins 2007-2018: overheating or temperature creeping up
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
- bearing noise from the front of the engine; overheating if run low
Its other signs
- coolant weep from the weep hole / front cover area
- coolant smell, occasional low-coolant warnings
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
7 NHTSA owner complaints match it, out of 1,355 checked
How it shows up
- temperature climbs only under load/towing/AC-high but stays normal unloaded
Its other signs
- fan roars constantly (stuck engaged) or never engages
- fan-clutch DTCs; belt noise from a wobbling clutch
How to tell it apart
- command the fan on with a scan tool and watch RPM response
- watch coolant temp vs fan-speed PID on a loaded drive
- inspect for wobble/free-play mechanically
Usual fix
replace the fan clutch (electric-controlled unit); verify the cooling stack isn't debris-plugged at the same time
Root cause, parts and sources →
verified
How widespread: Rare
3 NHTSA owner complaints match it, out of 1,355 checked
How it shows up
- white smoke, sweet smell; overheating events in history
Its other signs
- coolant loss, combustion gas in the cooling system, pressurised degas bottle
- 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 exhaustLosing coolantOil 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