Yeah inner cv boot. Better get it fixed before all the grease leaks out and you ruin the axle. They are not cheap...

Sent from my SM-G900P using Tapatalk

 

Clean off the inner boot and recheck, just because its dripping doesn't mean its the cause. I'm not sure of the color of the fluid, but if the motor mount above gave up it could have splooged its contents out onto the CV and then been flung around. Also in my experience CV grease is much thicker than what your pictures represent. Lift your coolant resevoir out of the way and see if you have fluid up by the mount.

 

That fluid is dark brown/black. I was going to say that if it isn't the CV boot and OP isn't using OE spec power steering fluid (should be green) then I'd check for oil on the underside of the oil cooler, around the cam gears, and under the plastic valve cover.

 

Hmmm...this is interesting guys. It's not the motor mount because I replaced that at 44,000 miles and did not see anything leaking in the area. I did replace the coolant expansion tank last month and it looked clean, also rechecked the tank for leaks as I'd initially thought. No signs of anything leaking under there. Perhaps I'll look again carefully. The fluid - I also thought it's kind of weird for cv boot/axle grease because this looks somewhat like transmission fluid. I test-tasted the coolant, brake fluid and oil and they are all different so I'm thinking the last thing it has to be is either transmission or power steering fluid. Could this be leaking from the seal connecting to the transmission?

 

Likely trans fluid running up the axle unless your power steering fluid isn't OEM green. Do you see it on the axle shaft going into the trans itself?

 

Had the same thing, it was the passenger side motor mount. Couldn't tell from the top, but it had cracked and leaked fluid out everywhere. But in this case it looks thinner than the viscous filling of the mount. I would also say the power steering fluid or maybe a cam seal leak.

 

The fluid isn't green that's for sure. I couldn't see that far in but whole boot is coated in fluid. When I parked at a gas station last night to check it was dripping (slow drop) from that boot. I guess when the car is running that whole rod spins? I can see residue as it splashed all over the area.

 

Just checked again and it is not the passenger side engine-mount, nice and dry. I'm suspecting trans fluid leaking through the axle seal. Also, what is that other pump? The little one pictured further. I see that boot is also coated, perhaps from flinging debris...?

 

That other boot is covering the joint on your steering rack. That's definitely not the culprit as it doesn't spin, so it wouldn't be flinging this liquid substance around. But it is in direct line to be covered by anything the inner CV has to throw.

I'm ruling out coolant or engine mount. Coolant would look very different, the engine mount doesn't hold enough fluid to saturate things that much.

Sorry if I missed it, but have you checked your oil level?
What's your mileage? Could be leaking cam seals. But that should show signs of oil dripping down the pan and block before getting to your CV boot.

Power steering fluid is possible since the pump is on that side...

I have a hard time believing this is transmission fluid since we're talking about the passenger side of the car. In order for transmission fluid to make it all the way to the boot, it would have to be riding down the entire axle shaft. You would have noticed the leak coming from the center of the car before coming from this side. Unless your skid plate has been collecting all of it.
Get under the car and check under your oil pan to see if there's any fluid leaking, or if it's clearly starting at the CV boot.

Also, are these original axles?
My bet is that this is CV grease. It's going to get very thin and oily once water gets to it and when it gets hot.

Remove the wheel and wipe off the boot. Then you can see if there are any cracks. Though, if these are original axles, at 9 years old, it's like the boot is just not tight to the axle anymore. The rubber expands and deteriorates with time, so even when there are no cracks, it can start leaking CV grease through the ends. Once you've cleaned off the boot, squeeze it by hand and watch to see if any grease squeezes out, also listen to hear if any air gets pushed out. The boots aren't going to be air tight, but it should have some resistance and not be like a dog toy squeaker.

 

I don't have an s40, but I'd bet cam seal too. Did you pull the cover and clean really well to see if it could be in there? Took my indy a bit to figure mine out on the R, and that's what it eventually was. Dye can be added and then using glasses and a light, you can begin to trace the source. He added it to the PS fluid and the oil to see which one it was. Two different dye colors, of course...

 

I had this exact same problem... at first thought it was an oil leak because of the small puddle on the garage floor and because the fluid was thin like oil and not as thick as I thought CV grease would be. Turned out to be a torn CV boot. Boot had a crack along one of the inner folds that allowed the grease to be flung all over the place. Take a good look & inspection of the boot... I really had to go all around each fold to find the crack in the rubber.

 

The reason it is leaking by the right tire is because my garage has a slight angle slope, so the passenger side is tilted about 8-10 degrees. I checked the oil pan drain plug, oil filter housing and oil level, all dry and up to level. Again, engine-mount is pretty recent and no leaks from there. Let's see what my indy guy will come up when he puts it on the rack later.

 

At the shop now. Car is up on the hoist, culprit is inner axle fluid. Mechanic slightly pressed boot and all came bursting out! Grease is heated into a thin fluid consistency, almost like oil. Will have to do both inner and outer boots as a kit.