D439E Service Manual 2. Engine Mechanical System (D439E)
107
Troubleshooting
Is oil pressure decreasin
?
Yes
Yes
Is oil level proper?
Check for oil leaks or mixture with
coolant.
Repair the damaged parts and replenish
it with oil to the proper level.
No
Yes
Is the oil viscosity normal?
Replace the oil with the proper viscosity.
Check fuel supply.
No
Yes
Do the oil pressure switch and
e unit
work?
Replace.
Yes
No
Is the filter element clogged? Replace the element.
Yes
No
Is the oil strainer clogged?
Is oil pump locked?
Is pipe cracked?
Repair or replace the faulty parts.
No
Yes
Do the relief valve and regulator valve
work?
Repair or replace.
Yes
No
Is there any damage or wear at the oil
pump body?
Replace the faulty parts
Yes
Is connecting rod or main bearing worn?
Repair or replace the faulty parts
No