Which areas have a problem?
Pick any that apply and we'll add those questions. Not sure? Skip ahead.
A · Diesel engine & fuel
B · Electrical
C · Emissions & aftertreatment
D · Fluid leaks
E · Air brakes, steering & suspension
F · Drivetrain
A · Diesel engine & fuel
Starting
Hard start when cold
Hard start when hot
Cranks but won't start
Won't crank
Long crank — approx. seconds
Wait-to-start light acting up
Block heater used
Power & performance
Low power / sluggish
Derate or limp mode
Surges or hunts at idle
Stalls — when:
Misfire / rough running / knock
Turbo whistle, surge, or no boost
Blow-by / oil from breather
Poor MPG — was / now
Runs hot / overheats
Using oil or coolant — how much:
Engine noise:
Where last fueled
Additives used
Problem started after a fill-up?
Yes
No
Not sure
Last fuel filter change — date
Miles at that change
Fuel concerns
Ran out of fuel
Suspected gelling
Winter blend / #1
Biodiesel B
Explain (engine & fuel)
B · Electrical
Electrical symptoms
Dead battery / won't hold charge
Lights flicker or dim
Accessory not working:
Only on rough roads / bumps
Recent electrical work or add-ons
Slow crank
Gauges erratic or dead
Blows fuses — circuit:
Only after running minutes
Explain (electrical)
C · Emissions & aftertreatment
Which emissions warning?
DPF / soot level
DEF level or DEF quality
SCR / NOx
EGR
High exhaust temperature
Derate countdown — mi. left
Already limited to MPH
Last DEF fill — where / when / from (pump, jug, tote)
DEF frozen, stored hot, or anything else added? Y / N
Explain (emissions)
D · Fluid leaks
Fluid color / type
Black or brown (engine oil)
Clear or amber, diesel smell (fuel)
Green, orange, pink, yellow (coolant)
Red (transmission / steering)
Clear, no smell, white crust (DEF)
Thick, strong smell (gear oil)
Don't know
Location
Front of engine
Under trans.
Rear of engine
Rear axle / diff
Wheel ends
Fuel tank / lines
DEF tank / lines
When
Only when running
Only when parked
Both
Puddle size overnight:
Explain (leaks)
E · Air brakes, steering & suspension
Air system
Slow air build-up
Air leak — location:
Compressor won't cut out / cycles a lot
Low air warning / buzzer
Air dryer purging constantly / never
Water or oil in air tanks
Brakes
Pulls to one side when braking
Wheel shakes when braking
Weak brakes / long stops
Brakes dragging or hot
Grabbing or uneven braking
Spring brake won't release / hold
Out of adjustment at inspection
Brake noise:
Suspension & chassis
Air ride leaning / not holding height
Rough ride / bottoms out
Fifth wheel won't lock / release / slide
Clunk over bumps — where:
Uneven tire wear — axle:
Explain (brakes, steering & suspension)
F · Drivetrain
Shifting
Grinds going into gear
Pops out of gear
Won't shift into gear
Shifts early, late, or harsh
Slips under load
Stuck in one gear / limp mode
Explain (drivetrain)
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