hgoodwiniii

Hi all. I am changing out the lower oil pan gasket on my C5 with standard transmission. I pulled the pan and gasket and got to cleaning up the engine surfaces that meet the gasket. I noticed a round channel that is accounted for on the pan and old and new gasket. There are 2 oil pan bolts that hold this area down. However, I can put my finger all the way up this channel and touch a bolt in there. As is, this channel will be exposed open once I put the pan and new gasket back on. I'm wanting to ask if I missed something and if this channel is supposed to have a plug or something to cover it or does it remain open with the pan and gasket in place? I don't see anything that came off that would plug it when I removed the old pan and gasket. Thanks.

Russell Boulding

Nothing goes in that hole you are good to go.

hgoodwiniii

Awesome. Thanks.

rodsvet

Put some teflon tape on the bolt threads for the lower pan. I changed my lower gasket a year ago and it seeped around a bolt head or two. Redrained the oil, pulled and cleaned each bolt, installed some tape torqued to spec, and no more seepage.

hgoodwiniii

Ok, too late. I had already put it back by the time I read your last post. I'll keep an eye on it. Thanks for the advice. I'm surely hoping that top pan gasket is not leaking. Looks like a bear to replace.

martysauto

The top is more likely to leak, it has to contain oil pressure.

hgoodwiniii

Hi Martysauto, have you ever changed the top gasket on a C5?

martysauto

Yes, but my engine was on a stand. You would probably have to drop the subframe.

leadfoot4

That's not good to hear. I was just changing my oil, before parking the car for the winter, and noticed the lower portion of the oil pan was "wet" with oil. I probably should have just broken out the torque wrench and checked the bolts, but I didn't have the car high enough off the ground at the time, to get under there safely, and properly hold the wrench, and didn't have the time to jack the car up properly.

It will have to wait until spring.....

hgoodwiniii

Ok, looks like I still have an oil leak so I'll get under it to check the torque of the lower pan bolts. If that's not the problem, upper pan or maybe valve cover gaskets. I'm pulling for the valve cover gaskets. How much work is it to pull that sub frame to get the upper oil pan off? Fun fun

leadfoot4

I'd check the area around the crankshaft seal.....

Sigforty

The remote oil cooler adapter/block off plates are known to leak. If you are seeing the oil near the oil filter or back of the engine on the driver's side you may want to check that.

Bill Curlee

The UPPER oil pan seal is a ROBUST aluminum gasket with an embossed rubber seal. Its pretty much bullet proof!

I highly doubt that it is the only cause of the leak. You CAN re-torque the upper pan bolts without too much trouble. You will need some LONG 1/4" extensions and a 1/4" drive ratchet. After re-torque, clean everything up and take a good drive and re-inspect.

I had a FRONT Cover damper seal fail and you would have thought that the entire engine had failed!! Oil was EVERYWHERE! Give that a check also along with the oil pressure sensor and cam sensor.

Bill

hgoodwiniii

Ok, I'll check around these areas. That damper seal is new. I sure hope that's not the problem. I changed that whole timing cover when I replaced the harmonic balancer back in Sept. with a Delco that hadh the seal already installed. That oil pressure switch is a new one from Orielly so I sure hope that's not it either. Thanks for the tips.

Russell Boulding

Did you add sealant to the timing cover/block/oil pan mating area?

Did you lubricate the front crankshaft seal? (you shouldn't)

What did you use to align the cover? (there are special tools)

Happy Hunting.

hgoodwiniii

Yes, No, Yes. I got under there last night and I'm happy to say that front timing cover, timing cover seal and lower oil pan gasket areas are all dry so at least I won't have to redo those. I'll get back under there to check around some more this evening. Thanks.

martysauto

I know what kind of upper pan gasket is on there. I have replaced a few because they were leaking on older high mileage ls trucks. What I suggested in my earlier post is if the oil pan was leaking it's much more likely to be the upper gasket because it has to contain oil pressure. A lot of oil pressure.
Hopefully the op checked the oil pressure switch early on if he reads the threads on this forum.

hgoodwiniii

Ok all. my car has me completely puzzled with this oil leak. Seems it leaks oil sometimes and sometimes it does not. I let it set for varous periods. Just before now, it sat for about 10 days, and no leak or at least no oil on the ground. Most recently, it sat for almost 2 weeks and there was a hugh puddle of oil on the ground this time. Any thoughts?

YELLO C5

Not sure where you're seeing the leak but I had a lot of oil getting sucked up in my intake that leaked over the valley cover and down the back of the motor. Wasn't enough to create puddles but made a mess out of underside and back of my car.

hgoodwiniii

What was the cause of it?