Internal Leak Somewhere

Hi Something i have noticed today, while cleaning, is that just behind the passenger seat, the carpet is wet. The wet patch is about the size of a tea plate. Never noticed before because ive always had the mats in the back covering the carpet. What can i do about this. How do i find out where the leak is coming from? I cant take the carpet out as its all kinda...fixed in! Its strange too. Its not like its anywhere near any windows, or vents. Its just behind the passenger seat, where the passenger would plonk their feet if they were sat in the back seat. Ive had no passengers in the back or anything..so im at a loss! Any idea's folks? Thanks James

My 760 saloon blows hot air out of something under the passenger seat so I'd hazard a guess that coolant/water might make it's way from the heating system to there ? Ben

You may be right James.

My mother informed me a while ago, that this damp spot has been present since ive had the car. Ive had the car now for 18 months, it flew through the MOT, so obviously its nothing REALLY bad but im just wondering, if its constantly damp, what are the chances that it might make the bodywork underneath rust? I'll do further investigation tomorrow and take a few pics to show the area im on about.

Hi, Do you have a sun roof James? It may be that there is water ingress from the B pillar (sunroof) or perhaps through the door vents (check the door seals - front and rear). The other dreaded possibility would be the heater matrix, but you usually get warer in the front, not rear, so maybe throughly check the front too... Des. . . ;)

I've come across water leaks on 200s and 700s originating from ill-fitting bulkhead grommets and manifesting themselves in the rear footwells, especially if the car is parked uphill. Might be a good idea to check the grommets, especially the ones on nearside. Also, is the drain pipe from the heater box to the bulkhead in place and unobstructed? I don't think that you will will have a rust problem, but I'd pull up the carpet and have a look and to dry things out. It's not too hard to do, just a bit time-consuming ;)

Ive gotta go out and get a handbrake cable in a little while, so while im at it, i'll check the other footwells for damp. Yes i do have a sunroof, and i do use it, but its never caused me any problems. the roof around the sunroof has always been dry :)

Hi, As Ivor suggested there maybe a roof leak then. But this should be covered by the sunroof drainage system. May mean youhave a disconnected drainage pipe, or a blocked pipe.. Des. . . ;)