I seem to suffer from a quite normal condition on my 300tdt from 1985, which is a pond under my right hand backseat after rainfalls. The water comes in from from the engine room somewhere and travels by the central locking cables under the passenger seat and turns into a little lake. If I donīt get this fixed, I might as well go buy some scuba gear soon...

This is most likely caused by clogged drains and/or a battery acid hole. There are loads of helpful threads on this issue, but after reading most of them I end up with the following question:

How many water drains does this car have in total?

There are 2 (or 4) in the engine compartment? Will I find more under the plastic grid by the wipers (I donīt think I can get them off without breaking the little plastic plugs)? 4 extra if you have a sun roof.

There is also a little rubber-nozzle on the underside by the passenger door. Is this also a drain?

Thanks!

fought this for a year before fixing it. Mine was a hole under the battery tray but the front drains were also full of crap. I found it by opening up the hood and running a hose on the windshield to see where the water pooled up. The main drains in the front empty in the wheel wells. But you need to make sure the water that pools is getting to these drains. There are a few places that trap water around the hood hinges that drain to the lower section that drains to the wheels. These have to be clean as well. Try the hose thing and look to where the water pools up. Some people have said a rear window seal will also cause this leak but mine was from the front.

There is a drain near the fuel filler neck, mine got clogged, and it took a while to clear that one. There are several drians in the trunk. There should be a drain plug towards the back of of the roof, behind the rain gutters, I believe this is to drain water that leaks through the sun roof seals. I think there are a few drains in the interior, but am unsure of this. I hope that this is of some help.