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Discussion in 'GS Boxers' started by davegaz, Jul 29, 2011.
...travelling north out of the heat. But Dave asked me about my repair.....I did use the loctite shown in the earlier post that comes in a can like pringles....unfortunately, I had first tried to fix the theads only with regular JB Weld. Should have known that wouldn't hold for long....So I actually used the loctite over the JB Weld, all around the threads. It's not real pretty, and for that reason, I ordered the $100 tool and the new plastic piece that includes the fuel pump, or some related expensive parts....for now I have those parts in storage, waiting to see if the loctite epoxy starts to fail.
Has been fine for some time, I really don't remember how long, but I know it's been well over a year.
OK, so today I was riding home at the bike was pissing gas in a near stream. My cracks have expanded.:eek1
I took it back apart and see where the design of the replacement female (male threaded) metal insert has a ridge that spreads the plastic.
As a temp fix, because I need to ride, I added some fuel resistent pipe threading and a thick washer to take the strain off the pump flange. I tested it for half an hour with no leak, but I am confident this will not hold.
I will be replacing the fuel pump, since the flange is not available seperately, when it comes in.
I'll post the home made tool I make to remove the large ring, and the process.
That sucks. But I have to say the timing is somewhat fortuitous for the rest of us.
This ridge you describe on the metal insert-- do you think it contributed to the problem? I was considering getting a new flange and immediately replacing the plastic quick connect with the metal ones, making sure they are not overtorqued. Maybe not a good idea?
As far as the availability of the flange, you might check the fiche for other bikes that may use the same pump to see if a separate flange is listed. For example, the 2010 GS uses the same pump P/N as the 08-09, but the flange is listed as a separate part only on the 08-09 fiche. Go figure.
So in my little worldview I have 4 data points. Mine cracked after 3 years. Roy's lasted 3 or 4 years. A friend's 2006 RT cracked right before his 3 year warranty expired. Jim's seemed to have lasted a little longer. Maybe I'll make the old pump into a piggy bank to save for the next one in 3 years.
May I suggest some alternatives to savage the fuel pump flange?
On my 05, I got this problem about 6 months ago on both flange!
What I did was to source for second hand flange and fix both the old and "new" flanges.
When the second hand flange came in(I got it from a guy in UK for less than $120 USD), it also has some cracks forming at the threaded area.
What I did was that I "plastic welded" the cracks line with a soldering gun and re-inforce it with expoxy coating. I use the epoxy to "strengthen" the extruding thread area so that it will be much tougher.
With these two prongs attack on the flange, the flange is still on my bike till today!
But please tale note that no every type of epoxy can withstand the petrol. If the "plastic welding" does not close the crack line properly, it will "eat" into the expoxy in a matter of time.
As sugested above, I will be looking for just the top part, but may not be sucessful.
I am also considering making and fitting a collar for the ridge around the female threads. If I can get a tight fit, and use some epoxy, it may solve the issue as well, and much cheaper.
As for the metal insert, it is identical to the plastic one, which may be the reason even the plastic ones fail. There appears to be some pressure put on the raised female portion by the ridge on the insert. Adding a small spacer moves the pressure to the top of the raised female threaded portion, removing the outward stress on the ridge, and forcing the sealing part to the threads. Not ideal, as the insert seems to want to seal on the contact point, think oil drain plug with a crush washer.
Speaking of that, maybe a washer made of semi-hard plastic would be a better spacer than a flat washer? I'll look into that as well.
I'll get some pictures to illustrate what I am thinking soon.
This is an unusual application of a pipe thread. As you know, pipe threads are tapered and as you tighten the joint the threads pull the tapers together forming the seal. The wedging action is what creates the high stress in the female collar. What's wierd is that the fitting tightens down all the way to where the hex "nut" face contacts the flange collar. A typical pipe thread joint will leave one or more exposed male threads. This ensures that the tapers are properly loaded and NOT the nut face. You don't want both.
By adding a washer, but you will lose the seal provided by the taper. You'll be relying on a thick layer of thread sealant. May work ok.
Like someone mentioned above, a straight thread with an o-ring would have been better.
The bigger issue may be the continued material degradation over time. The loads and stress on your flange haven't changed, but the cracks extended. This may be a warning sign, i.e., leak before break.
I agree, and this is why I think a collar around the flange might be the best route to follow. I am not crazy about using sealant to hold back 40+ psi.
Like the one on the right, with little or no lip to get in the way of the sealing edge.
I considered an O-ring, but there is no good way to make it work as is. The washer in installed puts the pressure on the top of the flange, and forces the thread tape to be the seal. It is working, but I do not know for how long as this is not the way it was designed.
They make heat shrink metal rings. They shrink completely at 100C so should be safe for the plastic.
Here is a link.
They are not cheap, but if they have one the right size these could fix a flange, they can exert a huge amount of force in a completely uniform manner.
If they work there is a vendor opportunity for someone.
It's a liability opportunity.
Instead of going hrough the hassle of making the collar, why not just pour epoxy over is like what I did?
Once it filled to the top of the collar, basically it is holding up the female thread like the collar you mention?
I am sure it will be much easier this way...
Mainly because I have little faith in epoxy in this application. It might work fine, but I have rarely had good luck with it under tension.
A collar will ensure that the plastic doesn't expand. I am hoping to find one and not have it made.
Oh... I agree with you to a certain extend! Let us know once you have found the solution to it!
Update. BMW comped parts and labor for a new pump. It took a while to get it done but all is well.
Shout out to Victory BMW in Chandler for making it happen.
That's good news.
500 miles so far and holding with a washer and thread tape. I really need to locate a collar though.
Flange failure in a 2006 model, Fuel Pump Assembly is $474.69
Never needed a collar, and at 1500 miles, it is still tight and not leaking.
:huh This is getting old.
I was aware of some of the other flaws such as EWS, FD, brake flange but was not aware of this problem. Just went out to check my 08 GS and it seems to have cracks.
I'll take the cover off in the next few days to get a better look.
What a burden we carry liking, no loving, these bikes.
The good thing is that mine is still under warranty.