Author Topic: Tall Fuel Pump Rebuilding (Bellows Seal)  (Read 633 times)

PeterPortugal

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Tall Fuel Pump Rebuilding (Bellows Seal)
« on: November 01, 2024, 11:32:41 »
Hi All,

I have had goes previously at rebuilding the tall fuel pumps and sometimes it was successful and sometimes not. The unsuccessful attempts have always been fuel bypassing the bellows and leaking out of the pump body.

I just came across this YouTube video (in Japanese I think) which is quite useful for anyone attempting a rebuild. The info in the Technical Manual is excellent but this video has a detail I haven't noticed on the board - the correct length to stretch the bellows to before installation. Supposedly 21mm. I am not sure whether this can be verified but in the absence of any other advice it is maybe worth considering for anyone doing a rebuild.

Link to Youtube and picture attached.

https://www.youtube.com/watch?v=f5VbKUzFvHc

Regards

Peter

1963 220se Cabrio
1968 280se Coupe

Pawel66

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Re: Tall Fuel Pump Rebuilding (Bellows Seal)
« Reply #1 on: November 01, 2024, 22:24:31 »
Thank you!

Very useful.
Pawel

280SL 1970 automatic 180G Silver
W128 220SE
W121 190SL
G-class

PeterPortugal

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Re: Tall Fuel Pump Rebuilding (Bellows Seal)
« Reply #2 on: November 02, 2024, 07:36:46 »
Hi Pawel, it is a really good resource. If you watch the end of the video he tests the pump successfully for an hour off the car. However, once installed in the car it leaks from the overflow pipe. The creator of the video puts this down to back pressure being present on the pump once installed. This increases the differential pressure across the seal and any small flaws in the rotating (bellows) or static (ceramic ring) parts of the seal are exposed.

This is the difficulty with these pumps and may have been one of the drivers for Bosch to develop the short version which doesn't have the seal.

He also has some comments about the quality of components in the aftermarket kits which are worth noting.
1963 220se Cabrio
1968 280se Coupe

MartinK

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Re: Tall Fuel Pump Rebuilding (Bellows Seal)
« Reply #3 on: November 02, 2024, 11:25:25 »
I replaced the bellow seal Into a radial seal ten years ago without any issues until today.
« Last Edit: November 02, 2024, 11:38:00 by MartinK »

PeterPortugal

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Re: Tall Fuel Pump Rebuilding (Bellows Seal)
« Reply #4 on: November 03, 2024, 12:12:53 »
Hi Martin,

Can you tell us where it is possible to buy this alternative seal?

Thanks

Peter
1963 220se Cabrio
1968 280se Coupe

MartinK

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Re: Tall Fuel Pump Rebuilding (Bellows Seal)
« Reply #5 on: November 03, 2024, 15:48:02 »
Sorry, but it is ten years ago. It is a FKM/FPM radial seal. (inner diameter) × (outer diameter) × (height). I milled out the casting and pressed the seal with some fuel resistant sealant into the casting.

stickandrudderman

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Re: Tall Fuel Pump Rebuilding (Bellows Seal)
« Reply #6 on: November 03, 2024, 19:06:06 »
https://www.sl113.org/forums/index.php?topic=35830.msg261741#msg261741

Not sure if anyone ever followed up in this lead.....

66andBlue

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Re: Tall Fuel Pump Rebuilding (Bellows Seal)
« Reply #7 on: November 03, 2024, 19:21:29 »
Sorry, but it is ten years ago. It is a FKM/FPM radial seal. (inner diameter) × (outer diameter) × (height). I milled out the casting and pressed the seal with some fuel resistant sealant into the casting.
Perhaps I can jog Martin's memory a bit.  :D
Reply #23: https://www.pagodentreff.de/diskussionsforum/threads/benzinpumpe-getauscht-motor-ruckelt.12501/page-2

http://www.agrolager.de/product_info.php?products_id=31000006
Alfred
1964 230SL manual 4-speed 568H signal red
1966 230SL automatic 334G light blue (sold)
1968 280SL automatic (now 904G midnight blue)

MartinK

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Re: Tall Fuel Pump Rebuilding (Bellows Seal)
« Reply #8 on: November 03, 2024, 20:19:29 »
Thanks, did not have this post on the map.  ;)

ja17

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Re: Tall Fuel Pump Rebuilding (Bellows Seal)
« Reply #9 on: November 05, 2024, 05:13:18 »
I believe Authentic Classics is now offering new reproduction brass bellows seals for the long fuel pumps!
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
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1965 220SE Finback

mauro12

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Re: Tall Fuel Pump Rebuilding (Bellows Seal)
« Reply #10 on: November 05, 2024, 18:27:02 »
Vintage Europe parts in USA offers a new reproduction of bellow seal . I guess the most difficult thing was to obtein this small but critical part .
Mauro Pisani
250sl 1967 5speed zf manual

PeterPortugal

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Re: Tall Fuel Pump Rebuilding (Bellows Seal)
« Reply #11 on: November 10, 2024, 07:33:32 »
I don't know who the supplier was (it was somewhere in the US) but the maker of the video was scathing about the quality of the parts in his rebuild kit, including the bellows.
1963 220se Cabrio
1968 280se Coupe