Did you use a gasket or RTV? If the pan is warped or damaged a gasket will not seal it. If the pan or case is cracked a gasket replacement will not fix it. Otherwise it could be leaking above the pan and you just can’t see it. Try an inspection mirror or camera.

 

I used a GM gasket.
I used a new pan.
The case is what the pan seals to with the gasket inbetween?
If "yes", I did inspect it carefully...seemed in very good shape, but a small crack might be easy to miss.. I will try the inspection camera approach to look above.. Great idea. Thanks.

My guess its the connecter to the transmission line that goes forward to the oil cooler in the radiator. They are a known failure its. Its an $18 part but a little difficult to reach. There is a thread out here someplace on it. Mine failed like clockwork at 75k miles.

Is this the connector for the line that drops down right below the trans fluid dipstick, or the connector (one of two) on the body of the transaxle it self? I think I can see one cooling line connector to the transaxle off to the right, near the passenger front wheel? The other connector I think is up front nearer the drivers side wheel and toward the front bumper, correct?

Forgot to say thanks for the inputs. Thanks!

 

My guess its the connecter to the transmission line that goes forward to the oil cooler in the radiator. They are a known failure its. Its an $18 part but a little difficult to reach. There is a thread out here someplace on it. Mine failed like clockwork at 75k miles.

 

Hopefully that will fix it, if not you might research drivers side output shaft bushing, it normally leaks while in reverse after sitting for a while. Lots of info here 4T80e Fix for leaky driver's CV shaft / output...

 

OK, jokes on me clip goes into the new fitting prior to the line going in. I was trying to insert the line into the fitting and then put on the clip. When reversed, the fitting/clip snapped as the line went in with a firm push (used a screw driver as a lever) . Found a nice youtube video:
How to Replace GM chevy Automatic Transmission Fluid Cooler Line Fittings - YouTube
Also, the new fitting is now costing $17.50 + tax.
I will post some photos when done, though it's a small little space up there where the fitting is, making the photos a little cryptic.
Gonna run it up on jacks (in park) with the heat shield not reinstalled for a moment and see if I get a leak.

 

Great news...12 miles of driving, 5 minutes of idling, and NO LEAK. So, Skyhawk, it looks as if the replacement of the fitting fixed the leak. Thanks to all for the great posts that were the only reason I was able to get this done. As promised..photos..(heat shield removed)

 

Glad to be of help. This is one of those things that WILL fail on the DTS. Now if you haven't already, replace the tensioner pillion the water pump. For less than $30 you will save yourself much grief. Its much easier than this job was.

 

Ordered parts today! Belt looked ok, but going to replace it as well.

BTW - car is for sale if you or anyone is interested. Mechanically I don't know a lot about the car history (that said my father in law was very punctual with oil changes per all the service slips in the car's document folder), but the paint, body and interior are fantastic.

 

 

I've posted some pics as requested by Skyhawk. Really a nice car.
I did the power steering belt tensioner pulley replacement ...thanks for the input.
I'm now trouble shooting just a slight pulsing when the car is braked hard. It's very subtle.
I inspected the rotors and brakes. Found the driver front caliper bolts weren't very tight. A little more than finger tight.
All the pads looked good.
I'm going to buy a dial gauge at Harbor Freight and check the rear rotors for flatness, as when the pulsing is felt, there is no steering while vibration.
Any thoughts on what this might be?

 

there is no steering while vibration.

This sounds serious, or you've flipped the words.

It could just be lack of use. The car's suspension is a bit sensitive about tire quality (but not as bad as the last Deville).