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Discussion Starter #1
I recently replaced the fuel filter on my '97 K12RS and the replacement gasket (where the assembly bolts to the bottom of the fuel tank) provided by BMW turned out to be considerably larger in diameter than the original - to the point where it would not fit the hole in the tank without wrinkling (and, hence, leaking). The part numbers on both are the same but, whereas the new gasket's dimensions are ~ 98 mm (OD) x 75 mm (ID), the original gasket's are ~ 90 mm (OD) x 70 mm (ID) - see attached pic. BMW Canada haven't been able to explain it and have referred the problem to "the fatherland" to sort out. In the meantime, I've successfully been able to get the original gasket to seal.

Has anyone else encountered this issue?? :confused:
 

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There are 2 flavors of gas tanks for the k12rs, the FP assy on the early ones were secured with a bunch of allen bolts and had problems with warping. The later versions were secured with a large single nut. My guess is they gave you the later version gasket.

hth!
 

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eric2 I thought that was right about the tanks. Now I go back to the parts fiches I can see they show both pump and gasket versions D=98 for both versions which threw me, However:

Up to 09/1998 the gasket part is 16112347604
From 09/1998 they used the cap nut and the part is 16142347285

So macdonge was supplied the later part for an earlier tank?



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Discussion Starter #4
I'm aware of the difference in the tanks (mine is the earlier one). The issue is that, while the part numbers molded into both the new gasket (which is too big) and the old gasket (which fits) are the same (16 11 2 347 604), they're miles apart in size. :confused:
 

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If BMW publish 2 different part numbers one for an early tank and one for a later tank, then logically you'd expect there to be a difference, unless their parts computer says if A OR B supply B. because they think the same gasket will fit both tanks. It sounds like a BMW parts supply issue unless they claim the later gasket is supposed to fit and they've just stamped the different part numbers on the same (later) part. I wonder what you get if you ask for the later part 16142347285. Perhaps you get the right part because the number stamper machine had the parts swapped over in the wrong bin at the time.

Fuel system components can be particularly hazardous if they are wrong. Imagine a BMW recall notice to all dealers who recently fitted a correct part number gasket like you, but the part was wrong. That would be embarrasing, as well as unsafe. I'd definitely be plugging away at your dealer for an answer.



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Discussion Starter #6
Problem solved!

Original problem finally solved. The factory eventually determined that my bike should have been subject to a Service Bulletin (#2816, Defect Code 00 16 02 00 00) back in '97 which would have changed out the fuel tank and fuel pump flange gasket. The new tank (introduced with production date 10/27/97) had a thicker wall thickness and all existing stock of the old gasket was supposed to have been returned (for disposal, presumably).

My dealer replaced the tank last week under "recall" at no charge. For any of you that might be afflicted similarly, I've attached a copy of the Service Bulletin (2 pages).
 

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Any additional help here with ID-ing old fuel cell?

Thanks for the info in this thread. I was having the same problem with my '98 K12RS - I replaced the fuel filter and now the fuel tank/pump flange leaks after closing it up. Looks like I might have an old fuel cell (that the Service Bulletin) says. In fact, the fuel cell says "96" and "97" in a circle in the plastic - which makes me think that was the year it was molded. Also, my bike was manufactured in Apr 97, just before the service bulletin.

Can anybody confirm whether my tank is the "old one" to be recalled? Not sure which number is the serial number. I think it's "11003/96-1"

There are no "white handwritten" numbers as described in the SB.

Thanks if you can help. Sorry the pics are not too good - trouble with the digi-cam and trying to get the angle right. Wish I had a white marker.

G100F16
 

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It's a while since I posted to this thread and somewhere else later on after I had a leaking tank and wrote about it. Here's a brief summary from what I remember:

I have the older (but confirmed replaced) tank with the bolts around the pump flange. I'd stripped it down, removed filler, sender and pump. I noticed curiously that the pump flange gasket was not so good a design as the sender gasket yet both seemed interchangeable.

Re-assembled the tank very carefully using original gaskets, put some gas in tank on the bench and pump flange leaked - WTF*!#?

Repeated the install a couple of times and same thing happened. Checked the tank body which didn't seem to be distorted. ABS thickness check confirmed it was newer tank. Read the bulletin - Replacement tanks have a 5mm wall thickness!

The answer is the pump gasket seems too large for the surface it is sealing so when you position it behind the pump flange it misaligns and you get a gas leak. Why is this? - because if you take their rubber gasket and spill any gas on it or it gets wet before you fit it, it expands. It also gets thinner when fitted a while too.

In the end I used some nitrile rubber sheet I had (3 or 4mm thick I think) and just cut a new gasket and punched the bolt holes, just like the one they used for the sender, but with a generous amount of rubber to fit and align around the inside edge of the hole and outside the pump flange.

I fitted this first time with stainless hex screws and it's been on the bike 8 months with absolutely no leaks. :)

Here are some info pics to look at (sorry, hadn't realised Macdonge had posted the bulletins)



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Thanks, voxmagna;

It turns out that my tank is the new one (according to the nearest BMW dealer and my VIN). I have found a sealant (aircraft fuel tank sealer) to create a gasket around the flange. I think your self-made 4mm gasket is a great answer and if this aircraft fuel tank sealer doesn't work - I'll look into your method. I assume this nitrile rubber material can be purchased at most auto parts retailers?

As a side note for others: I have the 5-screw attachment from flange to fuel cell. Amazing the warping (of the plastic fuel tank) between those 5 screws. No wonder they eventually went to a single flat nut to screw over the flange...evens out the pressure on the plastic.

My lesson learned...don't change the fuel filter unless it needs it!

G100F16
 

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I guess if the sealer is used for aircraft it might work, but I'd be nervous as this is one place you just don't want a leak. It might be used on aircraft, but is it still suitable between the ABS tank and metal flange?

I get my Nitrile rubber sheet from a UK supplier that sells nothing but various rubber sheet and molded profiles in a wide range of different rubber from ordinary to hi spec silicons. 3mm is right if you can get it, the 4mm I used was in the workshop and just a little thick - but no leaks. I've also got some really thin (about 1.5mm) I used for a timing cover gasket and that doesn't leak either!

Yes, you are right about some distortion, but mine hadn't a lot. What I did see was the possibility of the 5 threaded bushings set in the ABS pulling forward through the plastic(you never see that until the pump is bolted down). So check they don't sit above the surface. I think they are either counter sunk or counter bored. That's why I think my gasket (or even a new oem) works, as the bushings can pull through a little, but the gasket keeps the seal. DON'T overtighten!

Good Luck - Vox



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voxagna,

Thanks for your continued info and patience. Well, the aircraft fuel tank sealant aparently does NOT work. Jet A fuel is really similar to kerosene (or diesel), so I figured it would work with high octane mo-gas, but I guess not! It appears this epoxy-like silicon sealant breaks down upon contact with the gas...or perhaps it's when I go bumping down the road. I sealed it completely, let a couple gallons of gas sit on it for a day, then put in 2 and watched it for several hours...then put my fairing back on and rode it. Got to where I was going and returned to find a puddle under my bike. Oh, nice.

So - I'm gonna track down some of that nitrile rubber and cut a gasket as your picture shows. I'll also check for the screws pulling out.

The thing that bewilders me is the owner previous to me sealed it up with some sort of "form-a-gasket" type RTV-like material. However, now I can't seem to find anybody who makes one that works with gasoline. Permatex says theirs are "gas resistant" on the website, but the instructions on the package say "do not use with gasoline" and my NAPA dealer said he called them and they said they didn't have a gas-product. Mmmh. Will try your method and perhaps put the best RTV I can find around the outside. I'm tempted epoxy the sucker on and never change my fuel filter again!
:)
Thanks......G100F16
 

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The RTV type might work if it was left a day or 2 to cure, Epoxy isn't flexible and won't bond to ABS, so don't do that.

Gas is thinner than water, It's got a slight pressure head too, so even a microscopic hole will produce either a leak or a smell of gas. Don't take chances, seal it up properly with a decent gasket.

There must be a few aircraft with gas tank leaks!



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