KIA Niro: Engine Mechanical System / Troubleshooting

Symptoms :

 

Engine misfire with abnormal internal lower engine noises

 

Suspected area †’ Remedy

 

  • Worn crankshaft bearings  †’ Replace the crankshaft and bearings as required.

     

  • Loose or out of specification engine flywheel  †’ 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

 

Symptoms :

 

Engine misfire with abnormal valve train noise

 

Suspected area †’ Remedy

 

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.

 

Symptoms :

 

Engine misfire with coolant consumption

 

Suspected area †’ Remedy

 

  • Faulty cylinder head gasket or other damage to the cylinder head and engine block cooling system †’ Inspect the cylinder head and engine block for damage to the coolant passages and/or a faulty head gasket.

     

  • Coolant consumption may or may not cause the engine to overheat †’ Repair or replace as required.

     

Symptoms :

 

Engine misfire with excessive oil consumption

 

Suspected area †’ Remedy

 

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.

     

Symptoms :

 

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

 

Suspected area †’ Remedy

 

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.

Symptoms :

 

Upper engine noise, regardless of engine speed

 

Suspected area †’ Remedy

 

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.

 

Symptoms :

 

Lower engine noise, regardless of engine speed

 

Suspected area †’ Remedy

 

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.

Symptoms :

 

Engine noise under load

 

Suspected area †’ Remedy

 

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

Symptoms :

 

Engine will not crank.

Crankshaft will not rotate.

 

Suspected area †’ Remedy

 

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.

 

Special Service Tools

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