common sources of vortec oil leaks?

I've got a small oil leak coming from above the oil filter area.  Definitely not from the seal on the filter itself, but it is difficult to pinpoint due to all the view obstructions. 

Does anyone know what parts can be easily and/or quickly removed to aid visibility in this area?  For instance, I have read that there is an inspection cover for the bell housing.  Not sure if this would help. 
It is impossible to see any sort of oil from the top of the engine looking down.

You can try looking in through the bell housing's inspection cover but I'm not sure that would help very much.  I guess if things look dry in there you can rule out the rear main seal but about all you can see is the flexplate teeth.

I wonder if you are getting a leak from around the oil pressure sending unit on the top back of the engine on driver's side?

It definitely appears to be drivers side.  Of course, once it hits the oil pan it goes everywhere and drips down near the oil drain plug.  I'll look at the sending unit.  I'm probably going to have to get an endoscope with a light to be able to see better.

Well the manual says this, but you can try the oil leak detection kits that uses dye and a blacklight.

I don't know if yours has it or not, but mine has a factory aux oil cooler.

That thing has always leaked a little bit where it attaches to the engine for as long as I've owned the truck.

I've had new gaskets and had it tightened at several oil changes along the way.

I had a whole new fitting and tube set installed the last time I had an oil change because I was tired of seeing little oil spots on the driveway.

I just noticed it was leaking again.

Piece of junk.

EXT4ME said:

I don't know if yours has it or not, but mine has a factory aux oil cooler.

That thing has always leaked a little bit where it attaches to the engine for as long as I've owned the truck.

I've had new gaskets and had it tightened at several oil changes along the way.

I had a whole new fitting and tube set installed the last time I had an oil change because I was tired of seeing little oil spots on the driveway.

I just noticed it was leaking again.

Piece of junk.

Click to expand...

That's what you get for buying a caddie, LOL!

enoniam said:

That's what you get for buying a caddie, LOL!

Click to expand...

Its been a while since I followed up here.  I ended up changing the sender, but it was not the source of the leak unfortunately.    I don't think there is an oil cooler in the '03 Z71.  Since oil is not visible from the top half of the engine, I figured it was the pan or the rear main (neither of which I want to do myself).  Took it in to the shop, and they now suspect the valve cover gasket, but we put in some dye to confirm.  I'm bringing it back in next week.  I will be surprised if it really is the valve cover, because I can see that from the top... hmmm...  I may have to bust out the black light to look one more time before taking it back in next week.  Leaks can be tough to find... 

Rear valley plug maybe. I sure hope it's not.

marzahld said:

Its been a while since I followed up here.  I ended up changing the sender, but it was not the source of the leak unfortunately.    I don't think there is an oil cooler in the '03 Z71.  Since oil is not visible from the top half of the engine, I figured it was the pan or the rear main (neither of which I want to do myself).   Took it in to the shop, and they now suspect the valve cover gasket, but we put in some dye to confirm.   I'm bringing it back in next week.   I will be surprised if it really is the valve cover, because I can see that from the top... hmmm...  I may have to bust out the black light to look one more time before taking it back in next week.   Leaks can be tough to find... 

Click to expand...

Funny they mention that...

I noticed a couple of very small oil spots under our 2013 toward the end of the summer. I dismissed it as our neighbor parking in our spot while we were away(because you wouldn't expect oil leaks on a truck with 24k miles)... Then there was a point in the fall where the truck sat for a couple of weeks after a trip to Ohio. When it was moved next, there was a significant oil spot on the gravel underneath... When I discovered it, you could have knocked me over with a feather...  

When I crawled underneath, I noticed the oil had been dripping right at the drain plug. I could tell it was coming from above, running down, and collecting at the plug, but couldn't see exactly where it was coming from..

I dropped it off at the dealer, and they tried to tell me it was the Rear Main Seal leaking at first.. But, when they got in and looked at it, they discovered a leaking valve cover gasket.....

So if it is the valve cover gasket, I honestly wouldn't be surprised.. I am not sure how common it is on the 5.3 though. Our 02 never leaked a drop of oil up until the day we traded it in with 170k+ miles

>Rear valley plug maybe. I sure hope it's not.

Yikes!  that looks like you need to pull the engine to get to...    that valve cover looks relatively simple to replace, I'm keeping my fingers crossed...

Actually the tranny and flywheel.

Had valve cover gaskets replaced, and its still leaking...  they seem to swear up and down that the rear main is good...  hmmm...  what a pain.