Engine starting
Engine is hard to start when cold
If starting is difficult after a long stop but the engine then runs and restarts normally all day, focus on cold-start conditions: cranking speed, battery/power connections, preheating, fuel supply and air ingress, starting pressure, injectors, temperature sensors and compression. Smoke and its color during cranking are important clues.
Normal cranking speed first
Cold oil increases resistance and the battery supplies less current. Check battery, terminals, grounds, power cables, starter and actual RPM. Address slow cranking first. Also consider a hydraulic pump that fails to unload during starting.
Preheating
Depending on the engine, this may mean glow plugs, an electric intake heater, a heater grid or other cold-start aids. A fault can cause prolonged cranking, intermittent cylinder firing, rough running and white/grey smoke. Check the heater, power supply, relay, fuses, command and operating duration.
Smoke during cold cranking
Distinguish the following two patterns.
No smoke
Check fuel supply, air ingress, lift pump, low pressure, Common Rail, RPM, synchronization and injection permission.
White or grey smoke
Fuel enters but does not ignite properly. Check cranking speed, preheating, compression, injector atomization, injection timing, synchronization and the temperature seen by the ECM.
Air after standing
Typically it cranks for a long time after standing overnight, starts well all day and repeats the fault next morning. Check fuel drain-back or air ingress through hoses/connections, filter housing/seals, hand primer, check valve, lift pump and lines. Fuel need not leak outward. A major improvement after hand priming is a useful clue.
Fuel pressure
On Common Rail, observe how quickly cranking pressure builds. A slow rise may involve weak supply, air, filter, lift/high-pressure pump, metering valve, regulator or injector return leakage.
Injectors
Poor atomization particularly affects cold ignition: prolonged cranking, white smoke and rough running in the first seconds. On Common Rail also check excessive internal return leakage.
Temperature sensors
After a long stop, coolant, fuel and air readings should reasonably match ambient conditions. If the ECM sees a fully cold engine as hot, its starting strategy may be wrong.
Compression
A cold diesel is especially sensitive to low compression: long cranking, white smoke, rough initial running and improvement after warming up. Consider cylinders/rings, valves, clearances, valve gear, cylinder head and timing.
Fuel and freezing weather
Consider unsuitable seasonal fuel, waxing, a blocked filter, water and freezing in the separator.
What to observe
Cranking speed/duration, smoke, preheating, effect of hand priming, faults, first seconds of running and service-menu temperatures/fuel pressure.
Related problems
Further service support
Have a fault code?
Problem still there?
If these checks have not identified the cause or the fault returns, contact TSV Servis. The more initial information you provide, the sooner we can identify the next diagnostic direction.
What to send us
Machine/engine model, S/N, hours, ambient temperature, standing time, cranking speed, smoke, preheating operation, controller temperatures and actual/desired fuel pressure.
Include the make and model, S/N or a nameplate photo, engine model if known, operating hours, exact code or display photo and when the fault occurs.
Also tell us what you have already checked or replaced and the results. Include a photo or short video of the symptom where useful.
+420 722 307 850 · tsvcz@seznam.cz