Reserve Fuel Tank?

[Biodiesel300TD]

I have an 82 300TD, and I was looking through my owner's manual trying to find out at how many gallons the fuel light was supposed to come on. In the process I discovered that the manual says there is a reserve fuel tank. Is this standard equipment on all these cars? If so where is the reserve tank in my wagon. I read a few posts on this forum saying it was behind the spare tire, so I looked, and there is some kind of tank there but it seems like a strange place for a reserve tank. These cars just keep surpising me. Also when will my fuel warning light turn on?

Thanks for all your wisdom
Andrew

[Brian Carlton]

When the manual calls out the "reserve fuel tank", could this be simply the "fuel reserve". The reserve is the fuel available in the main tank when the light comes on. It's typically 2.5 gallons or so.

Or, is this a completely separate tank??

[MTUpower]

wagons did have an optional fuel tank which is found on ebay once in a great while (and was fitted in place of the spare), but all w123 ( I believe) wagons will have a fuel overflow tank behind the spare- looks like it could carry a gallon and a half.

[Ara T.]

So the W123 sedans dont actually have a separate reserve tank then?

[t walgamuth]

i dont think any of them have an actual reserve tank, in the wagons and in sedans there is a vacuum reserve tank which is black plastic. and in the wagons there is a windshield washer tank which is white plastic. i have never seen a reference to a reserve fuel tank or an overflow tank.

brian is correct in saying it is only in the main tank. the warning light is to tell you you are near the end.

[JimmyL]

I don't think it ever says fuel reserve "tank", I think it is just fuel reserve. Either way, it is just a reference to some fuel still available after the light comes on. The wagons do have an expansion tank in front of the spare. I'm guessing the wagons have one and the sedans don't do in some reason to the wagon tank being more flat, and the sedan tank being more upright. (maybe?)
Heck, what do I know.......