GM Gen III oil pumps (LS1, LS6, LS2, etc.)

NYSpeed Automotive
1

Figured I would write a little tech article on GM Gen III oil pumps after I heard of an uninformed local doing a camshaft / oil pump swap and put the whole thing back together to find little or no oil pressure. Little or no oil pressure can destroy an otherwise good engine very fast

2001+ GM Gen III oil pump (known as LS6 oil pump) - GM # 12566665 [SIZE=3]([COLOR=Gray]formerly 12563964)

This pump is a great upgrade for 98-00 LS1 engines and is a direct replacement. Along with the new oil pump you will need GM# [/COLOR][/SIZE]12557752 which is the oil pump pickup tube seal. They are $4.99 from most GM dealers. The new oil pump does not come with a seal. It is also VERY important that you do not reuse the old tube seal especially if it was the older seal GM# 12557075 that was used on the earlier LS1 oil pumps. The older seals were thinner and made out of black rubber. The newer GM# 12557752 is thicker and blue in color. Using the wrong O-ring or incorrect installation will cause air to be sucked into the oil pump instead of oil from the pickup tube. This aeration will cause little or no oil pressure.

TIPS:

  • never use an old O-ring - is your engine worth more than $4.99 + tax
  • lubricate internal pump with engine oil, if it is going to sit for a while you can use engine assembly grease, assembly lube, Lucas, Gel lube, etc. (something that will not run/drip off easily)
  • always install the NEW O-ring onto the oil pump pickup tube NOT the oil pump itself. If you were to install the O-ring into the pump you could cut a new O-ring while tightening or pushing the tube into the pump assembly

OIL PUMP

Removal

  1. Remove the engine front cover. Remove the engine oil pan.
  2. Remove the oil pump screen bolt and nut. Remove the oil pump screen and “O” ring seal. Remove the “O” ring seal from the pump screen. Discard the “O” ring seal.
  3. Remove the remaining crankshaft oil deflector nuts. Remove the crankshaft oil deflector. Remove the oil pump bolts. Remove the oil pump.

    Disassembly
  4. Remove the oil pump cover bolts. Remove the oil pump cover. Remove the drive gear. Remove the driven gear.
  5. Remove the pressure relief valve plug. Remove the pressure relief valve spring. Remove the pressure relief valve. Inspect the oil pump components.

    Inspection
  6. Clean the parts in solvent. Dry the parts with compressed air. Inspect the oil pump housing and the cover for cracks, excessive wear, scoring, or casting imperfections. Inspect the oil pump housing to-engine block oil gallery surface for scratches or gouging.
  7. Inspect the oil pump housing for damaged bolt hole threads. Inspect the relief valve plug and plug bore for damaged threads. Inspect the oil pump internal oil passages for restrictions.
  8. Inspect the drive gear and driven gear for chipping, galling or wear. Minor burrs or imperfections on the gears may be removed with a fine oil stone.
  9. Inspect the drive gear splines for excessive wear. Inspect the pressure relief valve and bore for scoring or wear. The valve must move freely in the bore with no restrictions.
  10. Inspect the oil pump screen for debris or restrictions. Inspect the oil pump screen for broken or loose wire mesh.

    Reassembly
    WARNING: DO NOT allow dirt or debris to enter the oil pump, cap the ends as necessary.
    NOTE: The internal parts of the oil pump assembly are not serviced separately, excluding the spring. If the oil pump components are worn or damaged, replace the oil pump as an assembly. The oil pump pipe and screen are to be serviced as an assembly. DO NOT attempt to repair the wire mesh portion of the pump and screen assembly.
    NOTE: Prior to assembling the oil pump, coat all wear or internal surfaces with clean engine oil
  1. Install the driven gear into the pump housing. Install the driven gear with the clean engine oil orientation mark facing the pump cover. Install the drive gear into the pump housing. Install the oil pump cover.
  2. Install the oil pump cover bolts. Tighten the oil pump cover bolts to specification. Install the regulator valve. Install a NEW regulator valve spring.
  3. Install the pressure relief valve plug. Tighten the pressure relief valve plug to specification. Inspect the oil pump for smoothness of operation by rotating the drive gear.

    Installation
    1. Align the splined surfaces of the crankshaft sprocket and the oil pump drive gear and install the oil pump. Install the oil pump onto the crankshaft sprocket until the pump housing contacts the face of the engine block.
  4. Install the oil pump bolts. Tighten the oil pump bolts to specification.
  5. Install the crankshaft oil deflector. Install the crankshaft oil deflector nuts. Tighten the crankshaft oil deflector nuts to specification.
  6. Lubricate a NEW oil pump screen “O” ring seal with clean engine oil. Install the NEW “O” ring seal onto the oil pump screen.
  7. Install the oil pump screen. Install the oil pump screen bolt and nut. Tighten oil pump screen bolt and nut to specification.
  8. Install the engine oil pan. Install the engine front cover.

NOTE: Inspect the engine block oil gallery passages. These surfaces must be clear and free of debris or restrictions.
NOTE: Push the oil pump screen tube completely into the oil pump prior to
tightening the bolt. DO NOT allow the bolt to pull the tube into the pump. Align the oil pump screen brackets with the correct crankshaft bearing cap studs.

:smiley: Happy modding