Leaking Fuel Pump Cover

[boxer]

Bike is a '98 11GS.

I've just replaced my fuel filter and can not stop petrol leaking from the cover [approx 7 to 8" dia that the pump+filter attaches to].

This happened last year and sealed for no obvious reason after I'd tried a few o-rings.

I believe that the cover itself is distorted despite using a torque wrench [6nm] and this is what's preventing a good seal being made.

The only things I can think of to do are:

1. Use sealant around the circumference. What sort of sealant? Would bathroom/window frame sealant be up the job? Would it breakdown in contact with petrol?

2. Make a gasket. Out of what? Then use this flat gasket as well as the o-ring.

3. Try and flatten the cover - penultimate option.

4. Buy a new cover [and fuel pump?]. It's this the final option I'm trying to avoid.

Any idea anyone?

Thanks.

Russ.

 

[littleredrooster]

Suspect that it would need a huge amount of distortion not to seal against the O-ring??? It's very easy for the O-ring to slip out of its groove when replacing the filter/pump assembly - are you sure that's not what has happened? Have you tried a new O-ring? If you try to put the same one back on after changing the filter, you will find that the ring has apparently stretched and will not sit properly in the groove. They do return to the correct size eventually - this can be hastened with a bit of warm air from a hair-drier. I have two in circulation - the one which comes off is left on the bench for a couple of days, and the old one is returned to service each time. Seems to work. When you DO replace it, do you tighten the nuts in a star formation, working across the opposite sides to achieve an even seal? If you work around the nuts in turn, it could be that you are pushing the seal out of the opposite side as it is tightened.

Good luck - let us know the outcome!

 

[boxer]

Thanks for your reply.

litteredrooster wrote:
Suspect that it would need a huge amount of distortion not to seal against the O-ring???
Russ replied:
I'd tend to agree, but it does leak. There is some visible distortion, this is the only abnormality I can see in the faces so I'm concluding this is the source of the leak.
-------------------------------------------------------
litteredrooster wrote:
It's very easy for the O-ring to slip out of its groove when replacing the filter/pump assembly - are you sure that's not what has happened?
Russ replied:
As sure as I can be.
--------------------------------------------------------
litteredrooster wrote:
Have you tried a new O-ring?
Russ replied:
Several. When this first occurred this time last year the problem just went away only to return late last year. Last year I must've tried 3.
-------------------------------------------------------
litteredrooster wrote:
If you try to put the same one back on after changing the filter, you will find that the ring has apparently stretched and will not sit properly in the groove. They do return to the correct size eventually - this can be hastened with a bit of warm air from a hair-drier. I have two in circulation - the one which comes off is left on the bench for a couple of days, and the old one is returned to service each time. Seems to work.
Russ replied:
Whatever the expansion/age of the o-ring I've never had any trouble with the size of the o-ring and the way it sit's in the groove. As far as I'm aware they've all seated just fine.
----------------------------------------------------------
litteredrooster wrote:
When you DO replace it, do you tighten the nuts in a star formation, working across the opposite sides to achieve an even seal? If you work around the nuts in turn, it could be that you are pushing the seal out of the opposite side as it is tightened.
Russ replied:
I work on opposite nuts in turn - star formation?
---------------------------------------------------------

Believe me, I wouldn't be seriously considering bathroom sealant if I could see any other way.

 

[Guzzler]

From experience and talking to others, if the plate is actually warped the recommended action is to replace it. And it isn't cheap.

If funds are low, you could try a little persuasion and try to 'un-warp' it. Not an easy task.

If you want to try a sealant, go to the auto supply shop and read the back of all the tube sealant's and find one that is compatable with petrol.

When tightening up the nuts to secure the plate, you do it gradually!!! Tighten a bit, move to the nut directlly opposite, tighten a bit, move back to opposite side an move to the right (or left, just pick one) a nut, tighten a bit, repeat the process. "Star Process'

It is a time consuming process, you end up touching each nut several times. You DO NOT want to tighten on nut completely then move to the next nut and tighten completely. This will still warp the plate.

 

[boxer]

Thanks for your replies.

Over tightening of the nut had caused the area around the hole to taper in, kinda like a funnel.

This is possible because the metal around the stud is slightly recessed thus allowing room for the cover to be pushed into it by over tightened thus giving the hole a tapered edge.

Because of this the area around the hole was below the sealing face thus preventing the cover from pressing on the o-ring.

flattening of the area around the hole was easy as the metal cover it very malleable.

I tightened the 6 bolts using a 8mm socket only, no bars, extensions, just my hand. When my hand slipped on the socket and I could tighten them no more I used a spanner and gave them half a flat. Used larger washers as well.

That's my theory anyway, and it seems to have worked.