Oil Leak on a 98 Yukon

[OilBurner2003]

Hello! I have a 1998 GMC Yukon, which just had a oil pan gasket, and new oil cooler lines replaced. But yet, the drip still persists. After spending 15 mins under the truck, it looks like the pan has oil on it, but where the transmission and oil pan meet, I can see this drip. Now my first thought was the oil cooler "Block" I'm not sure what it's called, but the starter on the other side is completely covered, but the oil cooler is fairly clean. So unfortunately, to me this looks like a rear main seal leak, even though I could be completely wrong. Any ideas?




Update! I crawled under today and realized the starter, which is covered in oil, Is HIGHER than the rear main seal. It's also on the side where the Engine oil pressure sensor is, right next to the cap and rotor. I believe I have found the issue; I will remove the cap and rotor to verify, but it just makes sense. If not, back to the drawing board. But with both valve cover gaskets done, Oil pan Gasket, oil cooler lines and fittings, this is the highest point in the engine that could physically leak, thanks to all the users here, I have a great place to start! Wish me luck!

 

[exp500]

Wash it well, take another look. Looks like rear main seal at first look.

 

[OilBurner2003]

Wash it well, take another look. Looks like rear main seal at first look.

I've cleaned that drip and the pan with everything around it a few times, and it keeps showing up in that main spot. I'm starting to believe it is the rear main seal, but I don't know if there's a way to check it somehow.

 

[exp500]

Wash seal area and flexplate with brakekleen or similar to near spotless. Run very short time and look again. Really sounds like you just dont want to believe it's leaking.
You could also try snake oil, works once usually, ask any used car lot.

 

[OilBurner2003]

Wash seal area and flexplate with brakekleen or similar to near spotless. Run very short time and look again. Really sounds like you just dont want to believe it's leaking.
You could also try snake oil, works once usually, ask any used car lot.

Only reason I'm not sure is because I need to look at the Engine oil pressure sensor too, which can also have this leak appear in this spot. I will brakekleen and come back with a update, thank you!

 

[Eman85]

Start at the top, oil sending unit and rear of intake manifold will run down. If you get everything clean iy will help. Spray foot powder will show you the trail sometimes when you're tracing an oil leak.

 

[OilBurner2003]

Thank you for that! I will check that sensor today, will update what I find.

 

[OilBurner2003]

Start at the top, oil sending unit and rear of intake manifold will run down. If you get everything clean iy will help. Spray foot powder will show you the trail sometimes when you're tracing an oil leak.

I think you had the right idea! I crawled under today and realized the starter, which is covered in oil, Is HIGHER than the rear main seal. It's also on the side where the Engine oil pressure sensor is, right next to the cap and rotor. I believe I have found the issue; I will remove the cap and rotor to verify, but it just makes sense. Thank you!

 

[exp500]

Oil pressure sensor located on engine left(driver) side top on bellhousing flange, behind fuel manifold lines and intake manifold. Starter normally right side lower block boss.

 

[OilBurner2003]

Oil pressure sensor located on engine left(driver) side top on bellhousing flange, behind fuel manifold lines and intake manifold. Starter normally right side lower block boss.

To me, it looks like the drip is coming from the sensor and travelling down to the bell housing. But the sensor IS leaking, put my hand on it and felt wet oil. I'm going to check it out and decide what to do there. I guess I should have also taken to consideration that the old leaky pan and lines might have also done that to the starter. But none the less, a leak was found, and I will fix it. Thank you for your input!