Where does oil typically leak from on 3100s?

[daswulfkralle]

I've actually, apparently, got a leak right at the sump. speaking of which, once my car is back on the ground, i need to check my oil....

[supreme_style21]

Nope I'm not losing that much yet, but soon enough I suppose.

[PCGUY112887]

For those who think their oil pump drive may be leaking on their 3100/3400, this is an easy fix that will save you a lot of money in oil! My old car had this gasket leaking, it's typically standard to replace it when a mechanic replaces the lower intake manifold gasket (since those all leak too!).

 

To just change the oil pump drive seal, first you need to get the gasket. There is a GM part number for it around here somewhere... it's super cheap. You will want to pull off your throttle body, and you should see the round top of the oil pump drive on the rear of the block above the transmission. It is right next to the lower intake, it's a close fit to pull it out.

 

There is a little bracket holding it down with a bolt through the bracket. Unbolt the bracket, and slowely pry up on the whole pump drive (round metal part sticking up). You should be able to get a screw driver between the block/pump drive. It will slowely come out, it's a few inches long and has some gears on it.

 

Don't let anything fall down this hole! It could cause a mess of problems trying to get it out.

 

What you pull out will be dirty, wipe it off a bit and you should see where the oring is on it. Pry it off, and carefully install your new oring on.

 

Wipe all of the leaked oil off your tranny/block (if you care), get the gear on the pump drive all oily with some fresh oil, along with the o ring. Side it back into the hole it came from, GENTLY tapping it down with a mallet or something. It will take a bit of force to get it to gear up correctly again, but you should not be hammering on the thing. This is sliding into place with your cam!

 

Make sure it's down tight, reinstall your bolt and anything else you took off, and clean up. You should be keeping your oil in your motor now.

[mfewtrail]

From your picture, it probably is the oil pump drive o-ring. When it leaks badly, oil will pool right where the drive is and then begin to run down the front of the engine in that area(right where the engine/trans meet).

[supreme_style21]

thanks.. that seems to be the source of the problem. It isn't getting fixed I don't think. Once my new house closes and I sell the one I have now, the GP will be retiring and will be replaced. It's getting up there in miles and beginning to show its age and I'm just not putting any more cash into it. And since I'm moving further away, I'll be running 50 miles a day for work, so I'm just not gonna put the GP out on that. She'll probably end up being a spare car.

[Masterchief362]

Great, that is exactly how the oil leak on my 3100 is looking. Time to replace that o-ring... all the oil spots in the driveway where I park is starting to look like I own a ford.