Overview
Note. When repairing engines, all parts must be contamination free. If contamination/foreign material is present when repairing an engine, premature engine failure may occur.
Note. For specifications refer to the appropriate engine mechanical article. For 2.0L GTDI, refer to the GENERAL SPECIFICATIONS , or for 3.5L Ti-VCT, refer to the GENERAL SPECIFICATIONS tables.
Note. This information contains, steps and procedures that may not be specific to this engine.
This information covers general procedures and diagnosis and testing of the engine system, except for exhaust emission control devices, which are covered in the appropriate service information articles .
The engine incorporates the following features
- Crankcase ventilation or breather system.
- Exhaust emission control system.
- EVAP control system.
Some engines incorporate a fail-safe cooling system. REFER to ENGINE COOLING .
Correct engine identification is required to order parts. For complete vehicle and engine identification codes, REFER to IDENTIFICATION CODES .
Normal Operation and Fault Conditions
Oil is drawn into the oil pump through the oil pump screen and pickup tube in the sump of the oil pan. Oil is pumped through the oil filter and then enters the main gallery where it is distributed to the crankshaft main journals, to both cylinder heads. From the main journals, the oil is routed through cross-drilled passages in the crankshaft to lubricate the connecting rod bearings. Controlled leakage through the crankshaft main bearings and connecting rod bearings is slung radially outward to cool and lubricate the cylinder walls as well as the entire connecting rod, piston and piston ring assembly. The cylinder heads are fed from a drilling into the supply passage feeding the main gallery. Main gallery pressure is sent through VCT circuit and reduced as it enters the cylinder head galleries through fixed serviceable orifices, located at the upper part of the feed passages. It is this reduced pressure in the cylinder head galleries which feed the camshaft journals, rocker arm shafts and the primary and/or secondary timing chain tensioners. The camshaft lobe, roller followers, rocker arms and valve tappets are lubricated by splash created through valve train operation.
Low oil pressure can be attributed to internal engine conditions including
- Excessive crankshaft end play
- Excessive main bearing clearance
- Excessive connecting rod bearing clearance
- Excessive camshaft bearing cap clearance
- Loose oil galley plugs
- Loose timing chain tensioner bolts
- Oil pump screen and pickup tube
- Restricted oil flow passages
- Worn or damaged oil pump