Author Topic: 300 sd fuel tank question  (Read 1527 times)

1980sdga

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300 sd fuel tank question
« on: 12 April 2011, 10:22 PM »
When I got the car I noticed that the fuel tank was awfully big and squarish. It fills up the place under the vacuum pod deal.  I decided to check out my funky fuel gauge and discovered that the tank looks like a conventional rounded, bumpy tank where the sending unit goes.

After thinking about it, I believe that I may have some sort of auxilliary tank or something.  Is this just how a regular diesel tank looks?  The big rectangular tank has a bung on the top with a hose running out of it.

Oh yea, the sending unit is under the first-aid kit depression.

I'll post some pics later.
Jon


Little by little I have grown fond of the infamous Auto Temp II we have in our 116's

jbrasile

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Re: 300 sd fuel tank question
« Reply #1 on: 13 April 2011, 06:20 AM »
1980sdga,

You most likely have an extra tank installed in your car. This was very common back in the 70's and 80's when Diesel fuel wasn't readily available at gas stations in the US. Your regular tank sits under the parcel shelf behind a steel plate, sounds like you have an additional tank which is actually taking up some of your trunk space. You may actually be able to remove it since Diesel is now pretty easy to find.

Tks,

Joe

1980sdga

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Re: 300 sd fuel tank question
« Reply #2 on: 13 April 2011, 07:49 AM »
Thanks Joe!  I'm still trying to figure out how fuel gets from one tank to the other though.  I drove the car around some with no back seat and noticed what sounds like a pump running so maybe that's what transfers the fuel?
Jon


Little by little I have grown fond of the infamous Auto Temp II we have in our 116's

jbrasile

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Re: 300 sd fuel tank question
« Reply #3 on: 13 April 2011, 08:32 AM »
I don't know how they did it, but I think you are right, there is a transfer pump that moves fuel from one thank to the other. I believe all you have to do is remove the extra tank, plumbing and electric pump to bring the car back to original and have more trunk space.

I remember that when I was looking at 300SD's back in the early 90's a car with that dummy extra tank would always put me off... ended up getting a super nice one owner 79 300SD (with no extra tank), my first MB, loved it!!!

Tks,

Joe

1980sdga

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Re: 300 sd fuel tank question
« Reply #4 on: 13 April 2011, 10:09 AM »
I'm actually glad it has the extra tank although it adds another dimension to troubleshooting the fuel gauge  :P

The guage was about FUBAR and required soldering of 2 wires that came loose inside it.  I'm not sure how it was even working at all!  I may have just tangled up the wires when I was inverting it after removal.

Man, I need to take photos when I do stuff so I can share!  I'm still not sure if it's OK but it worked when I tested it manually.
Jon


Little by little I have grown fond of the infamous Auto Temp II we have in our 116's

1980sdga

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Re: 300 sd fuel tank question
« Reply #5 on: 13 April 2011, 08:46 PM »



Some pics.  I'm not sure what that amp looking thing on the tank is. Maybe part of the old cell phone that came in the car?
Jon


Little by little I have grown fond of the infamous Auto Temp II we have in our 116's