Connection between battery tray repl. and water in passenger side
 

I have discovered water in the front passenger footwell of my 1992 300D, also seeping into the rear. So I'm reading some threads, noting various possibilities such as clogged evaporator drain, other drains, and windshield seal. But the one that caught my attention was the washers for the fastening bolts on the battery frame.

Recently, I just replaced my battery tray....old one was extremely corroded. I treated some spots below the battery tray with POR-15 and got a brand new tray, wanting to do as thorough a job as possible to deal with any rust. I did not notice any washers. So the current configuration is that the tray goes over the bolts and nuts hold it in place. Are there supposed to be washers there? If so, where? Below the tray? What kind?

Since this is the only thing that has happened to my car recently, I thought I would start with this.

Thanks.

I should add that I did the same thing at the same time on my 91 300D, the only difference being that, instead of replacing the tray, I painted it with POR-15. No water in this case (and neither did I notice any washers).

I have a few pin holes under my tray and had to get a new one as well. I used rust reverser for the short term. Por 15 and some glass mat coming soon.

Might want to just put some Teflon tape or thread sealer on those threads for good measure.

I have no leaks is the drain under the try clear?

Two areas to check
 

1.The Screws that hold the Plastic Rack that holds the ECU(s) [in the Compartment BEHIND the Battery] Broach the Top of the Passenger Foot Well.
AND mine still have some very flexible white RTV type looking sealant on them!
2.The Drain System for the Bottom of the Windshield is just above the Battery
Tray [and it's subject to, by now 20 years on] aging plastic trough and connections.

I removed the battery and the tray. Everything seems dry, so I would guess it's not a clogged drain?

How would I trouble shoot something like this? Where should I try pouring water to see if it comes out on floorboard?