Purpose of the fuel tank screen on w123 wagons? - PeachParts Mercedes-Benz Forum

treetrimmer · #1 10-25-2012, 05:32 PM

I understand the screen on the sedans, because the fuel tank supply line to the engine comes out of the middle of the screen. It's a primary filter in the tank. But on the w123 wagon, the screen just seems to be by its lonesome in the middle of the bottom of the tank, nowhere near the exiting fuel supply line(?)

What gives with this? Enquiring minds want to know.

qwerty · #2 10-25-2012, 06:15 PM

There are not-so-visible compartments inside the tank that make things work. The fuel has to pass through the screen on the way out of the tank.

Biodiesel300TD · #3 10-25-2012, 08:46 PM

The screens are slightly different. On the wagons the fuel actually filters through the upper part then the fuel through the holes at the base and goes through a separate passages in the bottom of the tank into the supply hose.

A sedan screen looks like this

While a wagon screen looks like this

vstech · #4 10-25-2012, 08:52 PM

the two look the same... one is laying on its side in the pic.
I should pull one of each and compare them side by side.

Quote:

Originally Posted by Biodiesel300TD

The screens are slightly different. On the wagons the fuel actually filters through the upper part then the fuel through the holes at the base and goes through a separate passages in the bottom of the tank into the supply hose.

A sedan screen looks like this

While a wagon screen looks like this

kerry · #5 10-25-2012, 09:31 PM

I have pictures of the screen and how it functions in a thread about my potassium hydroxide contaminated fuel tank. But for some reason, when I try to get into that thread, it shows a bad url. There's a small fitting in the bottom of the tank into which the strainer screws. That fitting has has a very small reservoir of fuel at the bottom which is filled thru the screen. Out of that reservoir a metal pipe runs to the outflow line for the tank. So, it functions basically the same way that the screen functions in the sedan tank.

Biodiesel300TD · #6 10-25-2012, 10:03 PM

Quote:

Originally Posted by vstech

the two look the same... one is laying on its side in the pic.
I should pull one of each and compare them side by side.

Look a bit closer John. The wagon tank screw has extra plastic at the end that threads into the the tank. That part has holes in it that the fuel flows through.

kerry · #7 10-25-2012, 10:09 PM

Quote:

Originally Posted by Biodiesel300TD

Look a bit closer John. The wagon tank screw has extra plastic at the end that threads into the the tank. That part has holes in it that the fuel flows through.

And that rim just above those holes seals against the top of the small reservoir.

vstech · #8 10-26-2012, 07:01 AM

ah ha! now that it's been described, it's obvious.

Yak · #9 10-26-2012, 09:24 PM

http://www.peachparts.com/shopforum/diesel-discussion/154459-how-does-tank-screen-work-123-wagon.html

Sketch in post 8.

Biodiesel300TD · #10 10-26-2012, 09:45 PM

Here is the diagram from post 8 in the link above. I found it curious that I asked the same question years ago, and now I'm here explaining it to someone else.

kerry · #11 10-26-2012, 11:13 PM

That diagram is accurate apart from the fact that the bottom 'chamber' only surrounds the immediate area of the screen and is maybe 2 1/2" in diameter. It probably only holds like 3 or 4 ounces of fuel.

The picture of that small 'chamber' is in this thread but when I click on it I just get 'bad url'. Anyone know what's going on or who gets a good url and can post the ling?

http://www.peachparts.com/shopforum/search.php?searchid=6387938