E30 Zone

my wifes facelift 2 door 320i has a small (but very stale and smelly) puddle under the carpet on the passenger side. there's no sunroof to blame and all door seals seem ok.

where's a good place to start hunting?

windscreen or from under the bonnet. 1st places to try.

If it appears to be coolant (coloured/ slightly greasy to the touch) then it is probably leaking from the coolant pipe that goes through the bulkhead to the heater. It is white and has a flange/join just inside the bulkhead which is sealed by an o-ring. when mine went, a new o-ring solved it. Bit of an arse to get to though, i had to remove the brake linkage to get at it properly.

good call. i'll have a look, though the water looked totally clear. the coolant on this car is fairly brown so it seems a little unlikely.

Another sign of this is if your windows steam up when you use your heater when its cold. If not, probably not these pipes then mate, sorry dont know what else it could be!

check for a rust hole in the bulkhead below or near where the wiring loom goes through the bulkhead. had one there on e30 before.
just remove the kick panel (speaker is behind it) and peel the carpet back to have a look. also while your there have a look at your jacking points very common problem

Dude, check out my thread in the tech section called Soggy Carpets, it's a parallel universe!

Basically, lift up the carpet from the front, may have to remove the kick plate and bonnet latch to get it up, see if it is wet under the carpet. Then pour a cup full of water into the vent cover under the windscreen and then see if water trickes down the footwell

Short answer to your question is it's either coolant from the heater matrix, the heater valve, the pipe O ring, or it's a water leak through one or more possible rust holes, or if you're very lucky, a blocked drain from the heater air intake/wiper motor housing.
If you're sure it's not coolant, then take the carpet out, and if you still can't find the problem, then get inside while somebody makes with a hosepipe.

well, it's not coolant, that's for sure.

time for a jetwash methinks!