Author Topic: Fuel tank questions  (Read 6161 times)

waqas

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Fuel tank questions
« on: May 11, 2009, 18:27:42 »
I had some leaky fuel hoses on my 1966 250se/coupe and decided to use the opportunity to drop the tank and have it boiled-out and re-sealed.

On removal, I noticed the following:
  • There were things rattling about inside the tank, which I assumed were rust particles.
  • However, they turned out to be long-lost pieces of an old fuel-sender. Once I'd fished out these 'spare parts', the tank was completely silent when shaken.
  • In fact, when I peer inside the tank (flashlights, mirrors, etc), it looks absolutely pristine.
  • The only sign of rust is some very slight surface rust at the filler neck.
  • The outside looks fine, with only minute amounts of paint loss.
  • The foam padding pieces that typically lie atop the tank (between tank and trunk floor) are mostly missing.
  • There is no flower pot inside!

I'm now seriously considering not having it boiled out or anything (at least on the inside). It would just strip off whatever original coating there is on the inside of the tank. I would also have to deal with all the issues with clogging lines, etc. Am I making a mistake by not doing it?

The outside looks alright, although a new coat of paint will probably make it look better. However, there are just a couple spots where the paint has exposed the metal underneath (and they are hidden above, so touch-up won't be minded there).

My questions:
  • What do you think?  Re-do the whole thing (with a risk of actually making it worse), re-paint just the outside, or simply clean and touch-up the outside?
  • Where do I get the little square pieces of foam padding for the top of the tank?
  • Why does it not have the flower pot? I thought all the fuel-injected cars from the 60's had these. (both my 230sl's do) Was this just an SL thing?
Waqas (Wa-kaas) in Austin, Texas

waqas

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Re: Fuel tank questions
« Reply #1 on: May 11, 2009, 18:34:06 »
This is exactly what I see when I peer inside:  (photo by Joe Alexander, from the Fuel Tank Tour)

Waqas (Wa-kaas) in Austin, Texas

glenn

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Re: Fuel tank questions
« Reply #2 on: May 11, 2009, 18:34:33 »
Wagas, Maybe it's not the first time---??  PO replaced the tank???  My 250SEs and 280SEs had the 'Tower of Fuelin'.

glenn

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Re: Fuel tank questions
« Reply #3 on: May 11, 2009, 18:36:33 »
Wagas, The pix is not the standard FI tank, IMHO.

waqas

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Re: Fuel tank questions
« Reply #4 on: May 12, 2009, 03:27:48 »
Whoops, looks like a post by the good Dr Benz has answered the third question (and indirectly the first as well). The post is here: http://www.sl113.org/forums/index.php?topic=1712.msg9443#msg9443 and basically confirms that this is not from a fuel-injected car. I wonder why it never gave me any running problems? (perhaps because I never drive it like a rally car around town). Now I need to go take a look at tank in the parts car...

So does anyone know where I can get pieces of the foam padding that are attached to the top of the tank? (cushioning between the trunk floor and tank top)
Waqas (Wa-kaas) in Austin, Texas

Rick

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Re: Fuel tank questions
« Reply #5 on: May 13, 2009, 16:40:38 »
Get it from your MBZ dealer-- I just ordered one for my car.  As I recall, it showed in the parts catalog with the fuel tank parts view.  It was around $5

waqas

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Re: Fuel tank questions
« Reply #6 on: May 13, 2009, 17:36:17 »
Get it from your MBZ dealer-- I just ordered one for my car.  As I recall, it showed in the parts catalog with the fuel tank parts view.  It was around $5

Thanks, it never occurred to me to ask them. All my dealer catalogues show the pads (about 8-9 of them) as attached and part of the tank, so I didn't think they'd be available separately.

Do you have the part number? How mach pad material is included?
Waqas (Wa-kaas) in Austin, Texas

waqas

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Re: Fuel tank questions
« Reply #7 on: May 14, 2009, 02:25:39 »
Ok, things are starting to get bizarre. I just got done removing a gas-tank from another 250se/coupe (a 1967 parts car) and what do I get? The tank has no flower pot either! What are the odds???  >:(
Are we absolutely sure that all fuel-injected cars had flower-pots?

There are slight differences with the other tank though:
  • The corners are square, not rounded.
  • There were little strips (about 100mm) of U-shaped rubber around the outer edges, near each corner.
  • The center 'bowl', where the outlet filter/screen sits, is a quite a bit deeper (as if it's meant to accumulate more fuel, like a very shallow flower pot).

Interestingly, the U-shaped rubber is reminiscent of the short rubber strips that were originally placed on the raised edge of the Pagoda's firewall. I wonder if a Pagoda's gas-tank should also have these short strips along the edges of the gas-tank...
Waqas (Wa-kaas) in Austin, Texas

ja17

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Re: Fuel tank questions
« Reply #8 on: May 14, 2009, 11:24:20 »
Hello,

I think that the main purpose of the flower pot is to keep fuel  available to the electric fuel pump when the quantity of fuel is low during "hard cornering".  You would most likely not notice any difference without the flower pot any other time.
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
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1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
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Benz Dr.

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Re: Fuel tank questions
« Reply #9 on: May 14, 2009, 15:15:41 »
All fuel injected cars have a '' flower pot* '' so those tanks you have are from cars that have carbs. I guess they'll work though or you would have noticed running problems by now.

I have tanks cleaned out all the time. If a car comes in with old gas in it I don't even think about it. One thing I won't do is get the tank coated with anything inside. If they're that rusty inside it's time for a different tank.






* copyright Benz Dr.
1966 230SL 5 speed, LSD, header pipes, 300SE distributor, ported, polished and balanced, AKA  ''The Red Rocket ''
Dan Caron's SL Barn

1970  3.5 Coupe
1961  190SL
1985   300CD  Turbo Coupe
1981  300SD
2013  GMC  Sierra
1965  230SL
1967 250SL
1970 280SL
1988 560SEC