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Old 10-28-2018, 11:57 PM
cn90 cn90 is offline
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DIY: E53 X5 Siphon Pump with Improved O-ring and Teflon Wrap

DIY: E53 X5 Siphon Pump with Improved O-ring and Teflon Wrap

- This is strictly maintenance as I don't want to be stranded by failed Siphon Pump.
My 2006 X5 runs fine down to Fuel Tank YELLOW light but I did this as preventive maintenance.

- If you don't want to do this job then:
1. Use Test #6 to periodically monitor the Siphon Pump function.
2. On very long trips, keep fuel above 40% at all time. This is b/c when the
Siphon Pump fails, the Right tank will go dry when fuel is less than 32L or so.
By keeping tank above 40% at all time, you are safe on very long trips.

- Special thanks to andrewwynn for being the pioneer of the E53 X5
Fuel Tank Design and Siphon Pump DIY.

- I put everything in this thread so it is easier for others.

- IMPORTANT threads...

---> E53 X5 Fuel Tank Design and Function by andrewwynn:
https://xoutpost.com/bmw-sav-forums/...stic-help.html

---> E53 X5 Siphon Pump Repair by andrewwynn:
https://xoutpost.com/bmw-sav-forums/...iy-repair.html


PARTS/TOOLS:

- Search ebay for PN 16116761645, but don't buy the factory O-ring.
Instead look for the listing with "Improved E53 X5 Siphon Pump O-ring".
This Improved O-ring is much better than factory O-ring b/c it is THICKER!

- Fuel Pump Removal Tool. I like OEMTOOLS 25156, about $18-$20 on ebay.

- Small hose clamp.





PROCEDURE:

1. Read the above DIYs by andrewwynn first!
Work outside with a low fuel tank, ideally less than 10L.
Open both REAR doors to vent fume.
Hit the center console switch to turn OFF the interior lights, to prevent draining battery.

* Remember the Siphon Pump assembly is not meant for rebuild like this, so you have to be creative when prying things apart etc. Proceed with CAUTION...


2. Lift the FRONT of the seat bottom upward and prop it up.
If you want to remove the seat from the car, then undo the 16-mm bolt
holding the middle seatbelt. I see no need to remove the 16-mm bolt.

3. Remove the four (4) 10-mm nuts, then remove the metal cover.

4. Remove the factory Oetiker clamp (during re-assembly, use a new small
clamp), and squeeze the sides of the connector to d/c the connector.
Use a right-angle pair of pliers, ROTATE the hose a bit to unseat it, then
GENTLY lift it upward. Do NOT break the plastic nipple.
If you break the plastic nipple, search forum for the repair using a brass barb fitting!















5. The White Plastic Collar slides along the rubber seal during factory installation.
So pry it UPWARD on all sides slowly, spray a bit of lubricant such as WD-40
to make it easier to slide upward.





6. NOTE that the design is:

Return Fuel (I think it is about 20-30 psi) ---> Plastic Nipple ---> "Coupler"
---> Two (2) black pipes to drive 2 separate "Suction Foot" devices.

The COUPLER:
- On top is the O-ring.
- On the lower part, it is a press-fit seal (not ideal but adequate for this).
The idea is to use "Improved O-ring", which is thicker and fits tighter for the
UPPER part of the Coupler and Teflon for the LOWER part of the Coupler.






7. To separate the Coupler from the Lid: press on the 2 tabs with a small screwdriver, then use a larger screwdriver to GENTLY pry it out.
- Remember that this was designed from factory for "single use" (i.e. "get a
new Siphon Pump if this fails") and not for rebuild like this DIY.

8. Once separated, you can see that:
---> The floater can theoretically get stuck at > 1/4, mine worked fine, but in
order to avoid that, I bent the floater a bit as shown to avoid the floater from
hitting the side of the fuel tank.
This is the part I don't understand: some people (car from factory ant not
repaired previously) had the floater stuck at 40%, causing stalling b/c people
think they have 40% of fuel, when in fact, they ran out of fuel.






9. The next step is OPTIONAL bc/ prying this apart is NOT easy with one person.
Basically wrapping Teflon to the LOWER part of the Coupler to prevent any
leak. However, the factory design is probably good enough with a "press-fit"
seal. Since I don't want to do this job again, I followed the advice by
andrewwynn to wrap it with Teflon.

- Prying this part apart is NOT fun, if you have a second person as helper, it
is better b/c you have to use small screwdriver to push the small tabs inward
while prying the fittings apart.
Work SLOWLY and METHODICALLY to pry it apart. You don't want to break it.
If you break this, time for new Siphon Pump!
Again this step #9 is Optional!

10. Install the new and Improved O-ring. I apply some engine oil on the
O-ring and it is a nice and tight fit (factory O-ring is a loose fit).












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