The BMW saddles
Just In case you want to drain your own bmw 7 series, 5 series or 3 series, some words of advice;
BMW’s by nature are low slung, they are also rear wheel drive, and have dual exhausts in most cases, which presents the designers a problem, of “where do we put a 80 to 100 litre fuel tank on a car where space is an issue”
They answerd this question with “saddle tanks” – these look like saddles literally and hang over the transmission tunnel and exhuasts, in the fuel draining business we have another word for this which is “pain in the a***” the trouble with saddle tanks is you cant drain them from the filler neck,, well you can but you can only retrive 70% of the contents of the tank, so…..
Instructions for draining BMW, 3, 5, 6 & 7 (mid nineties onwards)
Ensure the work area complies with ATEX regulations.
Lift back seat up, this just requires a jerk on the bottom bench
Remove bench from car, take care not to let it get mucky
you have now exposed the top of the saddles, there are 2 access panels, which are obscured by the deafening foam, the foam lifts off and you now have 4 bolts to undo, undo the bolts and lift up the hatches, the sender wire will still be going thru the hatch, be carefull not to damage these. also disconnect the return line which feeds into the top – (this is a return line and cannot be used to drain becuase it doesnt go all the way to the bottom – so dont get your hopes up)
Take a moment, and remind yourself that your are in the interior of a luxury car and you are about to handle some of the smelliest liquids known to man, petrol and diesel will stain and stink for years, so be carefull.
you are now looking at the big metal donuts which hold the top of the tank and sender unit in place, unscrew the donut, and you are now looking into the fuel tank from the top.
Insert the drain tube, and start draining, when you are done, make sure you are cleaned up before you start putting the interior back together.
You can use syphon if you have the height, or an old fuel pump from a car, dont use thin hoses, this is a big tank and u need a thick hose.
Make sure you have enough fuel cans handy, and only attempt this when you are working with another person, 1 of you needs to break the syphon while one handles the hose.
when done, be very carefull to put everything back together just as you found it, do not leave anything loose or untightend, be carefull that the pushclips are properly pushed together, and the donut screwed on as tight as it was when you took it off.
and dont use the “inhale fuel” syphon method! use a priming pump or jiggle pump, both cost just a few quid, syphoning with your mouth is unhealthy, dangerous and tastes disgusting!.
I have included a picture of a tank on sale on ebay from a 7 series in The US, its the same set up, this shows clearly how the 7 series operates what is basiclly a two tank system, the only time when it is a “one tank” system is when you are filling it and the fuel pours from one to the other, they have 2 sets of flow lines, and 2 sets of return lines, and two senders, this is not too disimilair to the old jag set-up, except the old jags did have 2 tanks – becuase they hadent figured out how to fill one from the other – a problem bmw solved.
BMW E65 745 745I 745LI 7 SERIES FUEL PUMP GAS TANK oem