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Look at this 17 gallon reserve fuel tank in my trunk!

Started by WrightSounds, 26 November 2012, 12:06 PM

WrightSounds

I recently purchased a 1980 300SD from a guy that had bought it from his uncle who had purchased the car new. His uncle was a WWII fighter pilot which translated on the Interstate to, "once he got on the road with his car, he didn't like to stop", so he had a 17 gallon reserve fuel tank installed into the trunk. So he had almost 40 gallons of fuel when filled up. He used to drive from Ohio to Florida... without stopping. It's gravity fed down into the standard fuel tank. The little red lever opens and closes the valve.

Anyway, I though it was pretty cool but a month later I'm thinking I'd like the thing removed. One reason beside it taking up a good portion of trunk space is that it's blocking access to the vacuum supply tank in the trunk. My central locking system isn't working and if that's the problem then I'll have to remove the tank to get to it.

Anybody ever seen something like this? IDK, maybe it's fairly common?









adamb

That's the most bizarre and IMO pointless addition to a W116 ever. Combined with the fuel economy of a 300SD, the standard 96 litre tank is plenty big enough giving a range of about 500 miles. And you've got to stop to take a piss anyway. Is there an additional container between driver's legs?  :o

WrightSounds

Quote from: adamb on 26 November 2012, 12:21 PM
Is there an additional container between driver's legs?  :o
Ha! No, but I'm thinking he should have had one installed for his poor wife that rode shotgun with him on those 1,000-mile road trips.

I'm right there with you adamb. It's gone from a novelty to completely superfluous in a few short weeks. I'm wondering how I'll plug the holes
that the tubing is going through?

s class

My red 6.9 has an apparently factory second tank behind the standard one. 
No change-over taps etc - its seamless, and gives a total of about 150 litres - which is only about 500 to 600km range when driven hard, so it does make sense......


[color=blue]'76 6.9 Euro[/color], [color=red]'78 6.9 AMG[/color], '80 280SE, [color=brown]'74 350SE[/color], [color=black]'82 500SEL euro full hydro, '83 500SEL euro full hydro [/color], '81 500SL

JasonP


It'll be good for days like this ....


http://www.youtube.com/v/hirZFmRwXvE

1979 300SD
Color: 623H "Light Ivory"
1979 300SD
Color: 861H "Silver Green Metallic"
1977 280 E
Color: 606G "Maple Yellow"
-------------------------------------------

WrightSounds

Ha! Well that's what most of my days seem like here so maybe I should keep it in there!

oversize

Quote from: s class on 26 November 2012, 01:55 PM
My red 6.9 has an apparently factory second tank behind the standard one. 
No change-over taps etc - its seamless, and gives a total of about 150 litres - which is only about 500 to 600km range when driven hard, so it does make sense......

I'd like to see that setup!!!  Most MB fuel systems have a 'reserve' tank, but I'm not sure I understand the concept....
1979 6.9 #5541 (Red Bull)
1978 6.9 #4248 (Skye)
1979 6.9 #3686 (Moby Dick)
1978 6.9 #1776 (Dora)
1977 450SEL #7010 white -P
1975 450SEL #8414 gold -P

oversize

Spillage on that custom tank would make one hell of a mess and it wouldn't be permitted here....  Unless you're planning regular long drives and hate re-filling to the power of 10, I'd remove it and regain some boot space...
1979 6.9 #5541 (Red Bull)
1978 6.9 #4248 (Skye)
1979 6.9 #3686 (Moby Dick)
1978 6.9 #1776 (Dora)
1977 450SEL #7010 white -P
1975 450SEL #8414 gold -P

wbrian63

17 gallons of diesel = 121 lbs (267kg) of additional weight to haul around as well.

In the 80's, I had a friend that purchased a late 70's Cadillac Fleetwood sedan from a former over-the-road salesman. It was equipped with the horrible GM converted gas-to-diesel engine. This fellow apparently didn't like to stop either, so he had two tanks in the trunk, one on each side of the spare tire.

I think "in those days" the availability of diesel was limited compared to today - that was probably some of the justification for the extra tanks.

For those uninformed, large GM sedans of that era had the gas tank mounted under the floor of the trunk, between the frame rails. The filler neck was reached by hinging open the rear license plate. The spare tire mounted on the "shelf" where the trunk floor rose up to follow the frame rails over the rear differential. In a full size car like this Cadillac, that left about 1 foot of space on either side of the tire.

The add-on tanks attached to the floor of the trunk and were contoured to follow the shape of this shelf, filling in the vacant space to the left and right of the tire.

Each tank held 10 gallons, which when added to the 26 gallon capacity of the main tank, provided nearly 1,000 miles of range between fuel-ups.

The installation was really cool becaused it used otherwised unusable trunk space. Not that the Cadillac suffered from a shortage thereof. Anyone shorter than 6 foot tall would have to crawl into the trunk to unbolt and remove the spare in case of a flat - that's how deep the trunk was.

This is one of the great things about diesel that is not available for gasoline-powered cars without special provisions: no need for vapor recovery, so the tank caps are sealed tight. The extra tanks in the Cadillac were gravity fed into the main fuel tank, with no valves required. You filled the main tank, then put the cap on and filled the extra tanks. They fed the main automatically. The fuel gauge would remain on Full for about 400+ miles of normal driving.

Of course, if you were stupid or otherwise uninformed, opening the cap on the main tank before the fuel gauge had begun to drop from Full meant a flow of diesel fuel out onto the ground and onto your gucci's...
W. Brian Fogarty

'12 S550 (W221)
'76 450SEL 6.9 Euro #521
'02 S55 AMG (W220) - sold
'76 450SEL 6.9 Euro #1164 - parted out

"Bond reflected that good Americans were fine people, and most of them seemed to come from Texas..." Casino Royale, Chapter V

JasonP

Quote from: wbrian63 on 27 November 2012, 07:46 AM
I think "in those days" the availability of diesel was limited compared to today - that was probably some of the justification for the extra tanks.



Copyright 1978, it came with my 1979 300SD.

I always try to go to the high-traffic diesel stations, to avoid diesel that has been "sitting" for a long time. My sister thinks that is silly, given how many people own pick-ups and farm in Kansas, but it is probably some wisdom from the days of yore.


1979 300SD
Color: 623H "Light Ivory"
1979 300SD
Color: 861H "Silver Green Metallic"
1977 280 E
Color: 606G "Maple Yellow"
-------------------------------------------

WrightSounds

I was thinking the same thing wbrian63... the extra weight. That's like two more kids in the backseat (I'm fine with just one for now :)
Plus the weight of the tank itself. I'm definitely going to take the thing out. I'm just wondering how I'll fill the two holes that were drilled for
the hoses that lead to the standard tank?

Thanks again for the input everybody!

andyatcrux

I own a 1980 300SD that has a reserve tank installed as well. It is fed through the same fill neck as the standard tank. At first I thought about removing it too. However, it has been useful for filling with the high quality B99 that Sequential sells here in Portland when the prices drop momentarily. I have saved $100 this year by being able to source it out at opportune times. Also, I am considering installing a switch to allow me to transfer over to B20,B50, or plain #2 diesel depending on temperature. Here in Portland it is possible to run on B99 almost year round with this setup. When diesel shot up to $4.60 here I was getting the B99 for $3.99 and will be getting a $.50 tax credit per gallon. That said, I do sometimes wonder about the possibilities of extra trunk space. If you do pull it, sell it. It will garner a pretty penny here in Portland.
1980 Ivory White 300SD. 295,000 miles.

WrightSounds

That's the only thing we're (my wife and I) are still debating. The loading up on cheap gas when it happens. I'm still even learning about biodiesel. If I were to use that all the time is it recommended to change the hoses? Or is that only if converting to veggie oil fuel? I'll have to read about all the different sequential flavors. I've got a lot of reading to do! Thanks again!

Is your W116 White?

andyatcrux

Biodiesel is a solvent. People often change to viton hose. I haven't. I have only changed the return lines and the "cigar hose" under the hood. They were slightly soft and weeping fuel. I did this before using the B99 and have not had to change the lines since in the year that I have owned the car.  Even Viton hose will wear out, so I am not a fan of the higher cost. Any wear on the hoses is very slow and easily spotted. Order extra hose from Autohauz and change as needed. You would need some fuel filters too if it has not been on Biodiesel recently. The stuff cleans the engine out. You will find good information all over the net. One thing I am planning on doing is adding an additional fuel filter to help with water separation. It has not been high priority due to the quality of B99 we have here having a very low water content for biodiesel.
1980 Ivory White 300SD. 295,000 miles.

andyatcrux

"Is your W116 White?"

It is a tan kind of color.....
1980 Ivory White 300SD. 295,000 miles.