Question01 grand am w/2.4 automatic. my car idles rough while in drive, i thought it was a motor mount but it stays stout while shifting through the gears sitting still. a expierenced mechanic told me that on these particular motors in these years they would come back to the dealer. most of them had problems with the oil pump malfunctioning while idling, sending to much oil to the motor causing the hydraulic lifters to stay open making it miss. does this sound possible and common enough to spend 83 dollars on a new one (oil pump) and all the trouble? a second oponion would be great. Thanks for the time?
AnswerHi
I personally have never ran into this (Oil Pump) and I worked at a GM dealership for many years.
That being said I do see the possibility of this happening from the theroy given.
I would think though, there would be other syptoms from excessive oil pressure. Have him check pressure at idle. see if it is in specs.
Here is ACTUAL GM Bulletin for your mechanic:
CONDITION:
SOME VEHICLES MAY EXHIBIT ONE OF A NUMBER OF CONCERNS RELATED TO THIS CONDITION. THE MOST COMMON SYMPTOM WILL BE STALLING ON INITIAL COLD STARTING, FOLLOWED BY HARD RESTARTING. OTHER CONCERNS MAY INCLUDE OIL FILTER CANISTER EXPANSION OR LEAKAGE AND HIGH OIL PRESSURE WHEN CHECKED WITH A GAUGE. SOME VEHICLES MAY ALSO EXHIBIT DIAGNOSTIC TROUBLE CODES P0300, P0301, P0302, P0303, AND P0304 INDICATING ENGINE MISFIRE CONDITIONS. OIL PRESSURE AT OPERATING TEMPERATURE MAY EXCEED 827 KPA (120 PSI).
CAUSE:
DUE TO A CONDITION OF THE RELIEF VALVE AND THE RELIEF VALVE BORE, THE RELIEF VALVE MAY INTERMITTENTLY BECOME STUCK CAUSING HIGH OIL PRESSURE. THE INCREASED OIL PRESSURE MAY CAUSE THE HYDRAULIC VALVE LIFTERS TO RAISE THE VALVES OFF OF THEIR SEATS CREATING A LOSS OF COMPRESSION AND ENGINE MISFIRE OR STALLING ON INITIAL STARTUP.
DIAGNOSIS:
IF THE VEHICLE EXHIBITS ANY OF THE ABOVE CONDITIONS, INSTALL AN OIL PRESSURE GAUGE CALIBRATED TO READ AT LEAST 1034 KPA (150 PSI) IN THE OIL PRESSURE PORT ON THE INTAKE CAMSHAFT CARRIER AND OBSERVE OIL PRESSURE AT 3000 RPM. THE OIL PRESSURE, EVEN IN EXTREME COLD, SHOULD NOT EXCEED 689 KPA (100 PSI). WITH THE ENGINE OIL AT OPERATING TEMPERATURE, OIL PRESSURE SHOULD NOT EXCEED 586 KPA (85 PSI). AT 3000 RPM.
CORRECTION:
IF THE OIL PRESSURE EXCEEDS THESE LIMITS, REPLACE THE OIL PUMP COVER WITH AN OIL PUMP COVER THAT HAS AN IMPROVED PRESSURE RELIEF VALVE AND PRESSURE RELIEF VALVE BORE.
SERVICE PROCEDURE 1. REMOVE THE RADIATOR OUTLET PIPE AND THE ENGINE OIL PAN, USING PROCEDURES OUTLINED IN SECTION 6A7 OR THE ENGINE MECHANICAL SECTION OF THE APPROPRIATE SERVICE MANUAL.
2. REMOVE THE BALANCE SHAFT DRIVE CHAIN COVER.
3. REMOVE THE BALANCE SHAFT DRIVE CHAIN TENSIONER SHOE.
IMPORTANT: DO NOT REMOVE THE BALANCE SHAFT DRIVE CHAIN OR BALANCE SHAFT DRIVE SPROCKET.
4. REMOVE ONLY THE OIL PUMP COVER ASSEMBLY.
5. INSTALL THE NEW OIL PUMP COVER ASSEMBLY GM P/N 24577081.
6. TIGHTEN THE FOUR LONG BOLTS TO 12 NM (106 LB IN).
7. TIGHTEN THE SHORT BOLT TO 10 NM (89 LB IN).
8. INSTALL THE BALANCE SHAFT DRIVE CHAIN TENSIONER SHOE AND THE BALANCE SHAFT DRIVE CHAIN COVER USING PROCEDURES OUTLINED IN SECTION 6A7 OR THE ENGINE MECHANICAL SECTION OF THE APPROPRIATE SERVICE MANUAL.
IMPORTANT: DO NOT USE EXCESSIVE PRESSURE WHEN INSTALLING THE BALANCE SHAFT DRIVE CHAIN TENSIONER. EXCESSIVE BALANCE SHAFT DRIVE CHAIN TENSION WILL RESULT IN NOISE AND WEAR CONCERNS.
9. REINSTALL THE ENGINE OIL PAN AND THE RADIATOR OUTLET PIPE, REFER TO SECTION 6A7 OR THE ENGINE MECHANICAL SECTION OF THE APPROPRIATE SERVICE MANUAL
