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How to Replace the oil pump drive shaft o-ring

About This How-to
Added: 07.27.03
Updated: 11.28.04
Discuss (18)

This how-to was written up by Mark West (with a few slight changes and images added by myself), and shows you how to replace the oil pump drive shaft o-ring. On the top of your 3.1, and newer 2.8, there is a round cover where the distributer used to be, before GM switched over to the DIS ignition. This is a very common place for an oil leak to develope, and this how-to will show you how to fix it.


  • O-ring, PN 10477565 - $2.60
  • TB coolant lines (optional, but I would replace them), the curved one is 10115742, $11.60, for the straight one I used a scrap I had. Or you can just bypass the TB heater!\
  • Some antifreeze to replace what you lose
  • Carb cleaner, since you might as well clean the TB while you in there


  • Basic Tools

How To Do It

Step 1

This cover is held down with a “C” bracket and one bolt and is actually the top of the oil pump drive shaft assembly. This assy is a shaft/bearing assy that has a gear on the top that meshes with the camshaft and a 6 sided hole on the bottom that mates to the oil pump. There is an O-ring on the top of this assembly that is right next to an oil journal. This O-ring breaks down and causes the oil leak that runs down the side of the engine and oil ends up EVERYWHERE. Mine only leaked when the engine was cold, when the engine was warmed up the flow would stop. This made it harder to find the leak.

Fix: The fix is to replace the O-ring on the oil pump drive shaft assy. The PN is 10477565 and the cost for me was $2.60. The entire oil pump drive shaft assy has to come out to replace the O-ring.

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Step 2

Remove the air hose that runs from the air cleaner can to the TB. There are two hose clamps that hold it on.

Disconnect the 3 vacuum lines on top of the TB, they are attached together.

Remove the two bolts that attach the TB to the intake plenum.

Remove the two coolant lines running to the TB. This was a PITA, I cut mine off and replaced them with new ones.

Remove the electical connectors for the TPS and IAC

Rotate the TB up and toward the master cylinder to lay it out of the way. Leave the mechanical cables attached. Also clean the TB while you have it out.

Click Here and/or here if you need more help removing, cleaning or bypassing the TB

Step 3

Depressurize the fuel system. Be very cautious here since you are dealing with fuel. Press in the release valve on top of the fuel rail while holding a rag over the top to absorb the fuel that will squirt out.

Disconnect the two fuel line fittings at the fuel rail.

Rotate the two fuel lines to the right (toward the drivers’ side front wheel) to lay them out of the way.

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Step 4

Remove the single bolt from the "C" clamp holding the oil pump drive shaft assy. Remove the bolt and "C" clamp.

Using pliers carefully grab the lip of the oil pump drive shaft assy and work the assy out. It took a bit of wiggling, but was not hard to get out.

Remove the old O-ring. Mine disintegrated into pieces.

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Step 5

Pour some motor oil on the new O-ring and oil pump drive shaft assy and work the O-ring onto the assy from the bottom up. The O-ring fits into the groove

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Step 6

Push the oil pump drive shaft assy back into the hole. This seems to be a "trial and error" thing to get it all to line up. I got it on my third try. If it won’t go in, don’t force it. Remove it, rotate the shaft a bit then try it again.

Replace the "C" clamp and bolt

Reattach the fuel lines

Reattach the TB and all of its assorted hoses and wires. After all of this my 3.1 does not leak a single drop of oil

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Step 7

Now hopefully your oil leak problem should be solved :)

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