08 GTS (957) Help locating coolant leak on pas side
 

Hey guys, I've been having this intermittent coolant leak that sometimes leaks and sometimes not. It drips from somewhere higher up onto the passenger side exhaust (and I can smell it burning off when it leaks), then drips down onto the subframe. It does slowly lose coolant from the res, maybe 2-3 notches on the min-max scale steps in the res over a course of a month or so. I only drive the car about once a week, usually on longer out of town trips. I looked on the pas side wheel arch under the hood but don't see any streaks from the res itself. Any ideas?

Drips on the exhaust pipe b/w front and rear catalyst, passenger side. Now that I look at these pictures blown up I see that the bolt holding the exhaust bracket is barely threaded in. No idea what that's about, but there's a nice big drip hanging off that bolt. :)
https://cimg8.ibsrv.net/gimg/rennlis...3f52b7135c.jpg

Drips on the sub-frame, where my finger is pointing:
https://cimg3.ibsrv.net/gimg/rennlis...79b72b41a6.jpg

I'm willing to bet that your plastic coolant reservoir is cracked on the bottom side of the unit. If I recall, these weren't a single piece of molded plastic. Rather the were two plastic halves welded together. It's extremely hard to see a leak because of everything being in the way but once you get up close to it and look below the reservoir, you will more than likely see a coolant trail. The reservoir isn't terribly hard to get to but there are a few things to get out of the way first. Not a hard job though.

And of course it mostly leaks while you're driving and there is pressure built up so when you're parked, the residual quickly burns off near the exhaust and there's often no leak on the ground. Drive it hard for 15 minutes and pull over. I'm sure you'll see steam coming up from the area.

It took me a while to find the leak on an older '06 S I once owned. It was a potential buyer who found it for me while on a test drive. Needless to say, he walked away from a great deal over this one item, even though the repair cost less than $120 at the time. Totally doable in the driveway if you're slightly mechanically inclined. Hopefully your's is as simple an issue.

Appreciate everyone's responses. I was about to pull the trigger on a new tank, but part of me still wanted to see the leak to make sure I'm doing a repair and not just throwing parts at the problem hoping for the fix. So I took the beauty cover off and for the life of mine I cannot see any leaks around the coolant tank. Yea, there's some dirt, but everything is dry. Also, I got the car warmed up and cooling system is holding pressure - did not put the gauge on it, but loosening the cap there was definitely pressure there.

Also, I fail to see how coolant would travel over from the strut mount wall and over onto the exhaust manifold which is not directly under the side wall.

Thoughts? I tried to climb under the car for a better look but the transfer case is in the way. I'd probably have to take the wheel and wheel liner off to stick my head in there.
https://cimg9.ibsrv.net/gimg/rennlis...6c1d8048c2.jpg
https://cimg8.ibsrv.net/gimg/rennlis...fffe31fbdc.jpg

the temp sensor is in the back passenger side, with an inspection camera you should be able to get a look at the area.
some pics
https://www.pelicanparts.com/techart...eplacement.htm

It appears the overflow goes through the hose into the wheel-well.. you might try replacing the cap. They are dirt cheap since VW uses them too on lots of models. Even places like AutoZone will have one in stock.

Mine is a 957 with a 4.8L, but worth checking. I just don't know how to even get in there without tearing things apart - there's hardly any room to stick the flashlight in there, let alone look behind. I think I'll have to take the wheel and liner off for better access, like I said.
Interesting point.
Another piece of information is that the coolant seems to leak most when I top it off to the max mark, then somehow stops when it drops to the min mark. Not sure what that's all about. The plastic seam in the tank is also just above the min mark to add to the confusion. Maybe I'll unbolt the tank and give it a proper visual inspection.

Either way, even if the coolant is dumped into the wheel well through the overflow tube, that does not explain how coolant end up on the exhaust manifold given there's a good 1-2" gap b/w the side wall and the engine the coolant would have to "jump over'. Unless it seeps down one of the hoses, but everything is dry.

You need to buy yourself a wifi boroscope off Amazon. Has been a godsend for less than $30!

wait till it's dark and use a blacklight, coolant leaks usually light up pretty well. You can find a UV detection kit from your favorite auto parts store or just buy a blacklight UV flashlight or a decent black CFL bulb

Sooo, the saga continues. Was doing tranny filter and took a peak at this coolant leak business. Spotted the obvious pink coolant crusties. The pic is on pas side looking from the bottom - the exhaust is the big dark thing on the right. Any ideas what this connection is and what to do about it? I'm not sure if this is the same leak as above though.

https://cimg3.ibsrv.net/gimg/rennlis...72648208a2.jpg