Removal of Oil Pump Drive

[truc0011]

I am in the process of replacing my lower intake and was told by the dealer I should replace the oil pump drive o-ring. I have removed the retainer bolt and clamp but the oil pump drive doesn't pull out very easy. What does everyone do to remove it? Pry on it with a screw driver or do you pull on it from the top??

Thanks for the info!

[cdru]

Pull on it from the top. The first time I tried to get mine off, I had a heck of a time getting it. What I ended up doing was getting a pair of sharp channel lock pliers that got a good grip on the top. I then used a pry bar in a gap between the pliers and the top of the shaft to pop it up.

Don't worry about screwing up the top of the cap; only worry about screwing up the surface where the cap meets the block. This means try to avoid forcing something between the two and prying up on it.

[gkindub]

Why replace the oil pump drive o-ring??? CDRU, you seem to have done alot of work on your 98 or 99 Montana--why or have you replaced the above mentioned o-ring??

[Glen_T]

Mind if I make a comment? I seem to recall that this 3.4L is an offshoot of the older 3.1L engine that used to have a distributor coming out the top of the engine. The oil pump drive is also driven off the camshaft in the same location, and I believe on that engine, the bottom of the distributor shaft had a recess in it that the long oil pump shaft plugged into (coming up from the pan). When they went distributorless, they put a plug in there that was basically just the bottom end of the distributor, with an o-ring at the top. On my old 1990 3.1L, the o-ring would begin to leak slightly at around 70k miles. Not sure if it was the wrong material choice by GM, but I suspect it gets pretty hot there and they may have a hard time keeping any polymer from drying out. I seem to recall my dealer didn't even charge me for the o-ring because it was such a common problem.

If the 3.4L is an offshoot from the 3.1L, then the o-ring may still leak on occasion....Glen

[truc0011]

Originally Posted by gkindub

Why replace the oil pump drive o-ring??? CDRU, you seem to have done alot of work on your 98 or 99 Montana--why or have you replaced the above mentioned o-ring??

Because it is the perfect time too. If it was to fail it would be alot harder to replace with the intake on the vehicle.

[cdru]

What Glen and truc0011 posted are exactly the reason. GM originally used a o-ring that wasn't designed well enough for the extreme temps and pressure it is subject to right there. As a result, the o-ring hardens and eventually leaks oil since it is subject to direct full oil pressure.

You will never have a easier time getting to it then when the lower intake manifold is off, so it's one of those things that you replace just on general principal. It's a $2 part that can save you a lot of money/hassle down the road if you had to fix it later. Some people also use the paper gasket the older distributor engines used as a "backup" gasket although I don't think it's really necessary.

There are also 2 other o-rings I suggest replacing. One is where the heater core pipe plugs in near the thermostat housing, and the other is where the bypass pipe plugs in near the water pump. Checking/replacing the clamps and hoses back in the heater core plumbing also will never be easier. Trust me, you don't want to have to replace a hose or clamp back there with the manifold on. There is no room. The 02 sensor also is right there...