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Exhaust back pressure too high
Cause
Corrective action
SCR substrate clogged with:
• Soot (resulting from engine
malfunction, e.g. injector
failure)
• Ash (resulting from wrong fuel)
1. Briefly connect engine load to blow off SCR substrates (soot
emission possible).
2. If exhaust back pressure does not fall: Contact Service.
Acrid and pungent smell in engine room or at exhaust outlet
Cause
Corrective action
SCR system faulty / leak in urea
solution system
1. Switch SCR system off, “Manual Switch-off SCR / IMO II / IMO III”.
• IMO III emissions requirements are no longer complied with.
2. Contact Service.
Black exhaust gas
Cause
Corrective action
Excessive load
u
Reduce load.
Air filter clogged
1. Check signal ring position of service indicator (→ Page 173).
2. Replace air filter (→ Page 171).
Injector faulty
1. Replace (→ Page 148).
2. Check exhaust back pressure.
SCR system clogged
1. Check exhaust back pressure.
2. Briefly connect engine load to blow off SCR substrates (soot
emission possible).
3. If exhaust back pressure does not fall: Contact Service.
Blue exhaust gas
Cause
Corrective action
Too much engine oil in the engine
u
Drain engine oil (→ Page 204).
Note: Engine oil burns in SCR system. Visually inspect SCR system
for damage resulting from overheating, leakage and signs of
sooting.
Oil separator of crankcase
breather contaminated
u
Replace oil separator (→ Page 135).
Exhaust turbocharger faulty
u
Replace (→ Instructions for Exchange of Sub-assemblies).
Note: Engine oil burns in SCR system. Visually inspect SCR system
for damage resulting from overheating, leakage and signs of
sooting.
Cylinder head faulty
1. Check cylinder compression.
2. Replace cylinder head (→ Instructions for Exchange of Sub-
assemblies).
Piston rings or cylinder liner faulty
1. Check cylinder compression.
2. Carry out endoscopic examination of cylinder liner (→ Page 131).
3. Replace piston rings (→ Instructions for Exchange of Sub-
assemblies).
4. Replace cylinder liner (→ Instructions for Exchange of Sub-
assemblies).
5. Contact Service.
86 | Troubleshooting | MS150123/01E 2017-05
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