Where do you guys think this leak is coming from?

[BrandonM3]

Yesterday I was changing my oil and noticed that there was a fine coolant spray on the pictured parts. I can't figure out exactly what is causing it though. I know it's small because 1) it's a fine mist which signifies a type of "pinhole" leak, 2) my car isn't overheating at all, 3) the coolant level isn't dropping by any noticeable amount, and 4) I can't find it!
I cleaned the parts yesterday to track the leak's progress, and today after driving around town, this is what I'm left with - basically the same as yesterday.

I recently installed the aluminum housing and both new radiator hoses. I can pull off that upper hose without draining the system right? I suspect it's something there. Before I go tearing things apart, what do you guys think?

Again, another justification for keeping a meticulously clean engine comapartment - being able to spot crap like this.

http://home.csumb.edu/w/wehmanbrandons/world/where1.JPG

Notice that it's spraying on the pulley too.
http://home.csumb.edu/w/wehmanbrandons/world/where2.JPG

[NYCMPOWER]

maybe the thermostat housing???

[fun2drive]

I suggest that you add some dye to the antifreeze and let it circulate. I had a leak and the dye made locationg the source easy. Most any car dealership carries the stuff in a little 4 oz bottle or so. It will help to reduce hunting for a mystery leak.
Hope this helps.....

[beatniks325]

you can remove the upper radiator hose without draining the system but you'll need to dump the coolant that is in the hose somewhere.

i'm guessing somewhere on the bottom/rear side of the upper radiator hose or the right side of the t-stat housing by the gasket.

[FierySphere]

An old trick is to spray foot powder on the area you think it's leaking from. The fluid will leave visible tracks in the powder. Use the spray on stuff, not the regular powder.

[ccc01]

Bet you a dollar its the metal thermostat housing - mine did the same thing until a week or so ago when it started to actually leave spots under the car. I'm going to buy a new composite housing and be done with this mess. BMW didn't use a metal housing there for a reason, apparently.

[blue///m3]

I had the same pattern and mine was the waterpump.

[weaksauce]

pin hole in the metal housing or a pinch hole in the hose. My money is on the housing.

[vmb]

did you determine the problem? I just noticed I'm having the exact same thing, it's almost like you were taking pictures under my own hood!

[beatniks325]

Bet you a dollar its the metal thermostat housing - mine did the same thing until a week or so ago when it started to actually leave spots under the car. I'm going to buy a new composite housing and be done with this mess. BMW didn't use a metal housing there for a reason, apparently.

they did a metal housing briefly in the 92 325's but switched to the plastic probably so they could make use of their fancy new mold technology and the "green" nature of the E36.

it is fairly common for the aftermarket aluminum t-stat housing to need some fileing and sanding to insure a flat mounting surface. some people also use a small amount of RTV sealent on the outside edges of the housing (do not use on gasket)

i highly doubt it is a pinhole leak from the aluminum t-stat housing; that is the kind of thing the metal housing is going to prevent over the aged plastic one provided you have a proper seal in the first place.

[endonuky]

Yes, these aluminum housings are not the finest castings; my first aluminum housing leaked, so I just got another one, and this time made sure both mating surfaces were absolutely clean and used some Hondabond, RTV type sealant. around the edges, but as formerly said, not on the thermostat O ring or the profile gasket. It's been on there 3 years now thru many track days and miles, and not a drop.

These Ronak aftermarket castings are not the best. I wish someone would make better one, but apparently not much money in it.

Phil