Shared Knowledge
"BMW X5 - Sudden and Unexplainable Loss of Washer Fluid"
2 October 2011
Summary: Most likely cause is the quick connect BMW used on the pump hose going to the rear hatch washer or on the hose going to the headlight washers.
Background:
BMW X5, model year 2000, 4.4i, 150,000 miles.
Periodically, without any explainable cause, "Washer Fluid Low" display.
At each occurrence, looked around washer tank but not could see or feel a leak.
Would simply refill reservoir and not see display for another 3 months, etc??
Problem\cause?
Removed nuts holding washer fluid reservoir to X5. (2) 10millimeter nuts. Bolts are part of chassis.
Lifted up reservoir and removed cable attached to fluid level sensor on bottom of tank.
Removed cable from all pumps.
Lifted tank higher and removed hoses from both rear pumps.
Pushed rear pumps fully down into tank rubber grommets and filled tank with water.
With cap off tank, water would leak out pump's discharge ports but with cap on, no water leak from pumps or from tank.
No crack in tank.
With no tank leak, then had to be where pumps fit down into tank or hose connections.
NOTE: you can potentially check for a tank leak or hose attached to pump leak, by filling tank about 1/4 full, leave cap off and then look and feel around tank, pump and hose connections.
Pumps and rubber grommets:
Upon examination, the 2 pumps on the rear of the tank, do not fit very tightly into the pump mould channel of the tank. It would appear to me that there was a design misconnect between the tank and the actual pumps as there are tabs in the tank and tabs in the pumps but if you place the pump in the tabs of the tank, the pump will not stick far enough down through the rubber grommet to seal properly.
Steps taken to fix problem:
Although rubber grommet that is fitted into tank is not under a lot of fluid pressure, decided to remove grommet and apply silicon sealant to the underside of the grommet.
Because pumps are only held in place by channel in tank and portion that sticks down into rubber grommets, decided to wrap upper portions of pumps with black electric tape to increase pump diameter and thus have pump fit tighter into tank channel.
Think I did about 10-12 turns of electric tape on each pump.
With grommets now sealed and pumps tight in tank "channels" reinstalled tank into X5.
When I went to connect rear hatch hose, finally noticed that it has a hard plastic elbow on the end that is pushed over the pump discharge. I am sure this was done to avoid the hose becoming kinked at the pump connection but as plastic connection does not fit very tightly over pump discharge port, maybe cause of leak.
When rear hatch washer is used, pump exerts pressure on line to rear and this forces elbow installed at pump to be pushed slightly away from the pump discharge port and thus opening up a leak.
Removed elbow from rear hatch hose line and rerouted hose from underneath tank to where it would connect easily to the pump discharge without kinking when pressured.
Looking at pump on side of washer tank that pumps washer fluid to headlight washers, it has a hard plastic quick connect on it could easily come loose under pump pressure. As headlights are only washed every 6 or 7 times the windshield is washed, could easily be the sudden loss of fluid.
Removed quick disconnect by cutting out of hose line and pushed hose directly onto pump outlet.