3.4L Oil Leak

[Backfire]

For quite some time I have been investigating an oil leak. It became progressively worse, until a few months ago when I pulled the intake manifold and redid the gaskets. I couldn't really see where the leak was, so I just did as good a job as possible resealing it with new gaskets and RTV. With the intake off, I was able to search the rear of the motor a little better, and it didn't seem like there was a leak from under the heads, as both seems dry at the rear of the motor.

Well, now a few months later the leak is back and better than ever. It has the same symptoms as before. There is oil on the starter bolts, front of trans pan, behind the manifold, and dripping on the y-pipe in the single tube area. The oil pan is dry on all sides, which had me ruling out rear main seal or pan gasket. The presense of oil on top of the block behind the intake also leads me to believe the bottom of the motor is fine. I can feel a small pool of oil on the driver's side of the block, but all of the underbody signs indicate a leak on the passenger side of the motor.

Aside from the intake and heads, is there anything on the back or top of the motor that would leak oil?. There is no sign of coolant in the oil which also had me looking for things other than the head gasket. Considering the leak is showing identical symptoms as before the new gaskets, I have a hard time believing that I could redue it and the leak would be in the same place if its only a gasket issue.

I am getting frustrated because it is so difficult to check anything on the rear of the motor, so I am stuck trying to reach around the sided and probe blindly! [img]tongue.gif[/img] Any suggestions would be greatly appreciated.

[ December 04, 2002: Message edited by: Backfire ]</p>

[3.4 slow to go]

the o-ring on the oil pump cover/decapitated distributor may have craped out. unfortunately, to get to it, you must remove the upper plenum. take the assembly to AZ, nappy, schlep boys, etc.. and match up the o-ring. while you're there, get a distributor gasket for any late 70's/early 80s chevy 350 motor. this will give you twice the protection than just the o-ring alone. This is apparantly a common problem on the 2.8/3.1 motors also.

[stagen]

<blockquote>quote:</font><hr>Originally posted by 3.4 slow to go:
the o-ring on the oil pump cover/decapitated distributor may have craped out. unfortunately, to get to it, you must remove the upper plenum. take the assembly to AZ, nappy, schlep boys, etc.. and match up the o-ring. while you're there, get a distributor gasket for any late 70's/early 80s chevy 350 motor. this will give you twice the protection than just the o-ring alone. This is apparantly a common problem on the 2.8/3.1 motors also.<hr></blockquote>

Yes and No. He is correct in that it is the O-ring in the oil pump gear drive. But, its a rather easy fix IMHO. You can buy the O-ring from the dealer, a few bucks plus ge the upper intake plenum gasket. At this point if you haven't replaced the o-rings on the fuel injectors I highly suggest you do.

1,2 ,3 - take the fuel rail out, take the upper plenum off, pull the oil gear drive out. Replace O-Ring, drop gear drive in, upper intake plenum gasket, plenum. New o-rings for fuel injectors, replace with fuel rail and your done. 4 to 6 hours tops taking your time :D

BTW - with my CAM'ed 3.4 i never had a problem with a leak using stock GM rings and seals

[ December 05, 2002: Message edited by: stagen ]</p>

[Backfire]

Darn it!!! When I had it torn apart I should have done some more research! :D I bet you two are correct, as that is the area the oil is pooling up top. From your descriptions is sounds like I just need to remove the upper plenum for clearance/room to work reasons, and that I shouldn't need to pull the lower manifold? How is the pump drive held in? My repair manual says something about a clamp but doens't show any images, is it pretty straight forward once you can see it in front of you?

I appreciate the help, my garage floor and I thank you!! Hopefully this will take care of the leak :cool:

[stagen]

Yes, upper intake and fuel rail need to come off. There is a clamp that goes over the gear drive. It's held in with a screw. Take that off. Next is the fun part. if the gear has never been out then you'll most likely need some muscle to pull it. If pulls straight up. I had to work mine for about 45 minutes with various tools. once it's off you'll see the O-ring.

Just a FYI - if you ever do a CAM swap this will have to come off in order for the CAM to come out. Replace the O-ring each time it's pulled.

[Backfire]

Ok, so I am through the easy part. I removed the fuel rail and plenum. I also removed the clamp from the oil pump drive. Now I am trying to remove the drive itself. What kind of tools did you use to pull it out? Right now all I can seem to fit are a few different pliers. I can just pinch the side and pull up. The top of the drive is free spinning but it doesn't feel like I have opened up any sort of gap between the bottom of the drive and the engine block. There also insn't enough room to wedge a screwdriver under it and pry it up. I just don't see my current method making any headway. Any thoughts/suggestions??

[img]graemlins/thumbsup.gif[/img] Update [img]graemlins/thumbsup.gif[/img]
I resorted to the vice grips and was able to free it up. I was cautious initially because I didn't want to ruin the cap of the pump drive, but said screw it and was able to loosen it up. Looked like there was a lot of oil above the O-ring groove, so I bet you guys were right. Is there supposed to be a soft O-ring in that groove, or just the 'hard' plastic ring that is there? I didn't see any signs of what I would call an O-ring when I removed the drive. If it is just the hard ring it looks like it could be a pain to replace. Or maybe the O-ring just fell apart, that would explain the large oil leak I guess.

When installing the new ring, do I need to lube it up will oil before install? Or should it be installed dry? I don't want to tear it when installing, and have the same problem right away.

[ December 08, 2002: Message edited by: Backfire ]</p>

[stagen]

The hard plastic black thing you are seeing is teh aged o-ring.

that needs to be removed and replaced. when installing it caot with oil and your good to go.

[Backfire]

<blockquote>quote:</font><hr>Originally posted by stagen:
The hard plastic black thing you are seeing is teh aged o-ring.
<hr></blockquote>

Knowing that now, I can see why the thing was leaking so much oil. I might as well have had it in there without the O-ring at all!!

Thanks again for all your help.