Replacing the Fuel Filter on a 1981 BMW 320i
(Despite the Ziebart anti-rust coating)

Fuel filter below axle:

Parts required :

  • Obtain proper replacement filter; Purolator makes most of them, and the various car manufacturers just add their labels
  • Ensure new copper crush washers come with the filter (or see below*)

Tools required:

  • 19mm box end wrench (open end is OK, but not as good) – for the bolts holding the fuel lines onto the filter
  • 22mm open end wrench that is fairly thin (or a thin 7/8 inch open end) – for holding the filter's integral (built-in) threaded nut in order to counteract the torque you will have to apply to the bolts when removing and installing them
  • Common screw driver, or better yet, a 6 mm box end wrench for removing the clamp that holds the filter to its bracket
  • Potentially some Armour All – to remove the large rubber band from around the old filter – so that it can be put onto the new one

Preparations:

  • Set up in a clean workspace (outside is OK, but there's a risk of contaminating the ground with gas, and contaminating the new filter with dirt)
  • Use a pit or car ramps if available, or a hoist if possible.  Jacking up the right rear of the car will work if necessary. A dolly to lie on and roll in and out under the car is nice to have.  [Above is a shot of a Ziebart coated fuel filter and the right rear drive axle - as viewed from the rear.]
  • Use goggles to protect your eyes – the gas can spray a ways out initially, and dress down (grubs)
  • Use rubber gloves if available
  • Have a container to catch about a quarter litre of gas (about one pint max) that will flow from the lines and the filter (good luck!)
  • Have some rags available to let the gas dribble onto so it doesn't splash off the floor – if that's what you're working on

Procedure used:

  • You will be 'operating' under the right rear axle of the car
  • Disconnect the negative terminal from the battery .  Any sparking source may ruin your day (car, garage, house, etc.)  This includes other vehicles that may have to leave the garage before you're finished

Removal.  With the container in place to catch the gas, and rags to catch what might miss the bucket, start by slowly removing the left side/driver's side (out flow) bolt. 

  • Nice and easy does it!  Don't be in a rush to remove the bolts from either end of the filter, let the gas that will leak out do so slowly – keep it a controlled leak! * Unless you have new copper crush washers, catch the old one as each bolt comes out – before you lose it into the gas or onto the ground
  • Next remove the right side/passenger's side (in flow from fuel pump) bolt.  It has the metal tubing which you must AVOID BENDING!  Use the larger wrench on the filter's integral threaded nut in order to counteract the torque. Try to keep its orientation during the whole removal/installation process – that will help to get a good fit right off the bat
  • Finally, loosen off the clamp that holds the filter onto its bracket, and slip the filter out toward the floating fuel line (toward the driver's side of the car).  [The resulting 'gap' is shown above - two fuel fittings and partly hidden, a bracket and clamp.]
  • Installation.  After you remove and clean up the rubber band from the old filter (using Armour All if necessary to get it off), slip it onto the new filter in about the same place.  Put the plastic plugs that came on the new filter onto the threaded nuts of the old filter - to  prevent more gas from leaking out.
  • Slide the new filter into its clamp from the left (driver's side) – ensure that the end marked Auslauf / Out and the arrow on the filter are pointing to the left (driver's side).
  • Attach the right side/passenger's side (in flow from fuel pump) bolt first, but ensure that you have a copper crush washer between the fuel line fitting and the new filter [see next photo].  Just snug it up for now - it will be tightened later.
  • Next attach the left side/driver's side (out flow) bolt through the floating fitting (with its crush washer in place).
  • Now tighten up the clamp to hold the filter (protected by the rubber band) onto its bracket
  • Finally, tighten up the fuel fitting bolts – about 20 ft-lbs should do it; and don't over do it.  Counteract the torque you apply with the open ended wrench holding the integral threaded nut on the filter.
  • Clean up, crank up, and know that it will take about three, 10 second long cranks to get fuel into the new filter and up the lines into the engine
  • Look for leaks right away (use a light if necessary), don't just look for drip marks on the floor/ground
  • No leaks? You're done!

Tips from experience:

  • Be prepared!  Safety goggles, gloves, container to catch the gas, etc. will keep you out of harm's way
  • If the darn BMW dealer gives you a filter – not in a box, with only one plug on the end, and without the new copper crush washers, ask politely to speak to the manager
  • The whole procedure – baring any badly rusted bolts, should take about one hour
  • Ziebart is good, but add gas and it's sticky!
  • For excellent information and photos on replacing or repairing fuel lines and fuel tanks, proceed to: http://www.coeinc.org/BMW320i/BeforeAfter.htm