Kia Niro: Engine Mechanical System / Troubleshooting

Troubleshooting
Symptoms
Suspected area
Remedy
Engine misfire with abnormal internal lower engine noises

Worn crankshaft bearings

Loose or out of specification engine flywheel

Replace the crankshaft and bearings as required.

Repair or replace the flywheel as required.

Worn piston rings
(Oil consumption may or may not cause the engine to misfire.)
Inspect the cylinder for a loss of compression.
Repair or replace as required.
Worn crankshaft thrust bearings
Replace the crankshaft and bearings as required
Engine misfire with abnormal valve train noise
Stuck valves
(Carbon buildup on the valve stem)
Repair or replace as required.
Excessive worn or miss-aligned timing chain
Replace the timing chain and sprocket as required.
Worn camshaft lobes
Replace the camshaft.
Engine misfire with coolant consumption

Faulty cylinder head gasket or other damage to the cylinder head and engine block cooling system

Coolant consumption may or may not cause the engine to overheat

Inspect the cylinder head and engine block for damage to the coolant passages and/or a faulty head gasket.

Repair or replace as required.

Engine misfire with excessive oil consumption
Worn valves, guides and / or valve stem oil seals
Repair or replace as required.
Worn piston rings
(Oil consumption may or may not cause the engine to misfire)

Inspect the cylinder for a loss of compression.

Repair or replace as required.

Engine noise on start-up, but only lasting a few seconds
(Check and compare with known good vehicle to determine normal condition.)
Incorrect oil viscosity

Drain the oil.

Install the oil of the correct viscosity.

Worn crankshaft thrust bearing

Inspect the thrust bearing and crankshaft.

Repair or replace as required.

Upper engine noise, regardless of engine speed
Low oil pressure
Repair or replace as required.
Broken valve spring
Replace the valve spring.
Worn or dirty valve lifters
Replace the valve lifters.
Stetched or broken timing chain and/or damaged sprocket teeth
Replace the timing chain and sprockets.
Worn timing chain tensioner, if applicable
Replace the timing chain tensioner as required.
Worn camshaft lobes

Inspect the camshaft lobes.

Replace the camshaft as required.

Worn valve guides or valve stems
Inspect the valves and valve guides, then repair or replace as required.
Stuck valves (Carbon on the valve stem or valve seat may cause the valve to stay open.)
Inspect the valves and valve guides, then repair or replace as required.
Worn drive belt, idler, tensioner and bearing
Replace as required.
Lower engine noise, regardless of engine speed
Low oil pressure
Repair or required.
Loose or damaged flywheel
Repair or replace the flywheel.
Damaged oil pan, contacting the oil pump screen

Inspect the oil pan.

Inspect the oil pump screen.

Repair or replace as required.

Loose, damaged or blocked oil pump screen

Inspect the oil pump screen.

Repair or replace as required.

Excessive piston-to-cylinder bore clearance

Inspect the piston, piston pin and cylinder bore.

Repair or replace as required.

Excessive piston pin-to-piston clearance

Inspect the piston, piston pin and the connecting rod.

Repair or replace as required.

Excessive connecting rod bearing clearance
Inspect the following components and repair or replace as required.

The connecting rod bearings.

The connecting rods.

The crankshaft pin journals.

Excessive crankshaft bearing clearance
Inspect the following components, and repair or replace as required.

The crankshaft bearings.

The crankshaft main journals.

The cylinder block

Incorrect piston, piston pin and connecting rod installation

Verify the piston pins and connecting rods are installed correctly.

Repair as required.

Engine noise under load
Low oil pressure
Repair or replace as required.
Excessive connecting rod bearing clearance
Inspect the following components and repair or replace as required:

The connecting rod bearings

The connecting rods

The crankshaft

Excessive crankshaft bearing clearance
Inspect the following components, and repair or replace as required:

The crankshaft bearings

The crankshaft main journals

The cylinder block

Engine will not crank.
Crankshaft will not rotate.
Hydraulically locked cylinder

Coolant/antifreeze in cylinder

Oil in cylinder

Fuel in cylinder

1)

Remove spark plugs and check for fluid.

2)

Inspect for broken head gasket.

3)

Inspect for cracked engine block or cylinder head.

4)

Inspect for a sticking fuel injector and/or leaking fuel regulator.

Broken timing chain and/or timing chain gears
1)

Inspect timing chain and gears.

2)

Repair as required.

Material in cylinder

Broken valve

Piston material

Foreign material

1)

Inspect cylinder for damaged components and/or foreign materials.

2)

Repair or replace as required.

Seized crankshaft or connecting rod bearings
1)

Inspect crankshaft and connecting rod bearing.

2)

Repair as required.

Bent or broken connecting rod
1)

Inspect connecting rods.

2)

Repair as required.

Broken crankshaft
1)

Inspect crankshaft.

2)

Repair as required.


Repair procedures
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Special service tools
Special Service Tools Tool Name / Number Illustration Description Crankshaft front oil seal installer A : 09231-G2100 (installer ...

Other information:

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Kia Niro 2017 (DE HEV) Service Manual: Special service tools
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