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K100-forum.com » Technical, repair and troubleshooting » Engine and transmission » Fuel Tank Leaking

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1Back to top Go down   Fuel Tank Leaking Empty Fuel Tank Leaking Mon Sep 05, 2022 4:28 pm

bmwk100rs

bmwk100rs
Silver member
Silver member
My fuel tank is leaking around the fuel level sensor plate. Has anyone here experienced this type of leak before and do you have a suggestion on how to fix it? TIA!
Fuel Tank Leaking Img_3118
Fuel Tank Leaking Img_3117

    

2Back to top Go down   Fuel Tank Leaking Empty Re: Fuel Tank Leaking Mon Sep 05, 2022 5:02 pm

bmwk100rs

bmwk100rs
Silver member
Silver member
The leak seems to be coming through the O-ring (part #: 62 16 1 459 608). I just ordered it.
Fuel Tank Leaking Img_3119
Fuel Tank Leaking O-ring10

    

3Back to top Go down   Fuel Tank Leaking Empty Re: Fuel Tank Leaking Mon Sep 05, 2022 6:53 pm

Laitch

Laitch
Life time member
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It's interesting that you ordered the correct part number using an incorrect diagram of the part. You must have traveled through a hole in the matrix. An illustration of the correct part is attached. The next challenge is likely to be getting gasoline from a diesel pump. Laughing
Fuel Tank Leaking Scree201


__________________________________________________
1995 K75 86,000 miles
Fuel Tank Leaking Usa-lo10
    

4Back to top Go down   Fuel Tank Leaking Empty Re: Fuel Tank Leaking Mon Sep 05, 2022 6:55 pm

Rick G

Rick G
admin
admin
That picture is of the early type you will find the correct O-ring from 86 onward. I cant recall the size but Real OEM will give you the size.


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 2004 K1200GT 1999 K1100 LT.
    

5Back to top Go down   Fuel Tank Leaking Empty Re: Fuel Tank Leaking Sat Sep 10, 2022 12:58 pm

robmack

robmack
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RealOEM doesn't list the size of the O-ring that seals the fuel sender unit.  I checked the Canadian price for the original BMW part and BMW want $23.00 plus HST.  For an O-ring!! Highway robbery!

As far as I can tell, the correct size metric O-ring should be 4.5x45.  That has a cross-section of 4.5mm, OD of 54mm and ID of 45mm.  This is eye-balling it; can anyone else confirm?


__________________________________________________
Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

6Back to top Go down   Fuel Tank Leaking Empty Re: Fuel Tank Leaking Sat Sep 10, 2022 2:38 pm

Laitch

Laitch
Life time member
Life time member
robmack wrote:As far as I can tell, the correct size metric O-ring should be 4.5x45.  That has a cross-section of 4.5mm, OD of 54mm and ID of 45mm.  This is eye-balling it; can anyone else confirm?
Euro Motoelectrics confirms.
Fuel Tank Leaking Scree204


__________________________________________________
1995 K75 86,000 miles
Fuel Tank Leaking Usa-lo10
    

7Back to top Go down   Fuel Tank Leaking Empty Re: Fuel Tank Leaking Sat Sep 10, 2022 3:24 pm

bmwk100rs

bmwk100rs
Silver member
Silver member
How much torque do you apply to the screws? Will 5 foot-pounds be sufficient?
Fuel Tank Leaking Img_3120

    

8Back to top Go down   Fuel Tank Leaking Empty Re: Fuel Tank Leaking Sat Sep 10, 2022 4:52 pm

duck

duck
Life time member
Life time member
There's no spec for that torque in the BMW manual. Just get them nice and tight.


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
98 Taxi Cab K1200RS
14 K1600GT
http://www.ClassicKBikes.com
    

9Back to top Go down   Fuel Tank Leaking Empty Re: Fuel Tank Leaking Sat Sep 10, 2022 5:51 pm

robmack

robmack
Life time member
Life time member
Laitch wrote:Euro Motoelectrics confirms.
Fuel Tank Leaking 212902


__________________________________________________
Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

10Back to top Go down   Fuel Tank Leaking Empty Re: Fuel Tank Leaking Sat Sep 10, 2022 6:37 pm

robmack

robmack
Life time member
Life time member
FYI:  Found a good source for these O-rings on Aliexpress.  5.0mm CS instead of 4.5mm, but they are Vitron which is good if you're using E10 fuel.

Search for this title "CS 5mm OD16-100mm Green FKM Fluorine Rubber O Ring O-Ring Oil Sealing Gasket" to get to the product.  If I posted a link, it would probably be broken in a couple months.

UPDATE: Received the o-rings from Aliexpress in the mail. They fit perfectly and the slightly extra thickness helps to seal a little better than an OEM o-ring (5mm versus 4.5mm).


__________________________________________________
Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

11Back to top Go down   Fuel Tank Leaking Empty Re: Fuel Tank Leaking Tue Aug 08, 2023 11:35 am

taube

taube
active member
active member
Having the same issue as the OP

My tank is leaking from this plate, so I ordered the replacement o-ring from EuroMotoElectrics.

I also found the FKM Viton O-Rings robmack mentioned on Aliexpress, so I've ordered '55mm OD x 5mm thickness'. Yes I'm buying a redundant part, but it's very cheap, and AliExpress takes ages to ship anyway.


__________________________________________________
Restoration project: 1988 BMW K100RS
Currently riding: 2019 Honda CBR300R
    

12Back to top Go down   Fuel Tank Leaking Empty Re: Fuel Tank Leaking Tue Aug 08, 2023 2:10 pm

Point-Seven-five

Point-Seven-five
Life time member
Life time member
I get my o-rings at the industrial bearing shop.  Viton for about $3.  They have them in stock, no waiting.  You should find your local shop.  Good prices on bearings, too.


__________________________________________________
Present: 1991 K100RS "Moby Brick Too"
 
Past:
1994 K75RT "Ilsa, She Wolf of the SS"
1988 K100RS SE "Special Ed"
1994 K75S "Cheetos"
1992 K100RS "Moby Brick" R.I.P.
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

13Back to top Go down   Fuel Tank Leaking Empty Re: Fuel Tank Leaking Tue Aug 08, 2023 3:01 pm

IainM

IainM
active member
active member
I had the same leak from the fuel sensor plate which was easily fixed by cleaning the mating surfaces and replacing the O-ring. It has been fine since and this was ~ 5 years ago.

Iain

    

14Back to top Go down   Fuel Tank Leaking Empty Re: Fuel Tank Leaking Sun Aug 13, 2023 2:20 am

taube

taube
active member
active member
Alright, I replaced the o-ring and it stopped the leak from my fuel level float plate.

As Iain noted, cleaning the mating surfaces helped tremendously. My sender
unit accumulated a lot of rust... I think the old o-ring might have been fine, but it could no longer seal after being disturbed because the surface was so rough. Photo is before a WD-40 and wire brush treatment.
https://i.imgur.com/4heJ5GV.png


__________________________________________________
Restoration project: 1988 BMW K100RS
Currently riding: 2019 Honda CBR300R
    

15Back to top Go down   Fuel Tank Leaking Empty Re: Fuel Tank Leaking Sun Aug 13, 2023 2:30 am

bad boy

bad boy
Life time member
Life time member
taube
looks like your K needs quite a bit of TLC
I wish you lots of success


__________________________________________________
Cheerz, David

Fuel Tank Leaking 9438-010

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1997 Peraves Super Ecomobile: a Kevlar reinforced monocoque with outrigger wheels, seating two.
K100 fork, monolever, headlight, indicators, K1100RS gearbox and K1200RS 589 engine, rear wheel
    

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