fan/blower motor
scoave
08-07-2004, 07:21 PM
I'm new to this board.
I have a friend whose '81 733i may need the fan/blower motor replaced, speaks of a burning smell last time she turned it on (has not turned it on since...).
I want to help her out, have rebuilt several heater boxes for BMW 02s, not familiar with E23s.
Looking for advice: how difficult is it to replace the blower motor in her 733i, she has A/C (I suppose they all do).
TIA
Scott
I have a friend whose '81 733i may need the fan/blower motor replaced, speaks of a burning smell last time she turned it on (has not turned it on since...).
I want to help her out, have rebuilt several heater boxes for BMW 02s, not familiar with E23s.
Looking for advice: how difficult is it to replace the blower motor in her 733i, she has A/C (I suppose they all do).
TIA
Scott
jeffreyb4me
08-26-2004, 08:59 PM
access is from the engine bay, remove the cowl cover on the firewall below the wiper grills and have at it.
Steve Fisher
08-27-2004, 02:20 PM
I'm new to this board.
I have a friend whose '81 733i may need the fan/blower motor replaced, speaks of a burning smell last time she turned it on (has not turned it on since...).
I want to help her out, have rebuilt several heater boxes for BMW 02s, not familiar with E23s.
Looking for advice: how difficult is it to replace the blower motor in her 733i, she has A/C (I suppose they all do).
TIA
Scott E23 BMW 7 Series, 1977-1986 fresh air fan/motor replacement.
Scott, this is a 2-3 hour job to change the fan-motor over.
FIRST CHECK THE FUSES, WHICH ARE IN A CLEAR-LIDDED COMPARTMENT IN THE CENTRAL LEFT HAND SIDE OF THE ENGINE BAY.
The European open ceramic centred fuses with an outer metal fuse link are subject to external corrosion. All of the fuses in BMWs of this era should be changed every 3-4 years, to reduce the resistance at each end of the fuse body to "fuse-holder" connection.
As a first step, rotate all of the fuses in their fuse holders, with the idea of abrading away any corrosion between the metal parts to get the lowest possible resistance. This should be a standard maintenance procedure every 6-12 months. If the fuse link is sitting proud (away from) the ceramic body, this is an indication of excessive heat, which could be local to the fuse because of poor connection to the fuse-holder ends. OR BECAUSE THE MOTOR BUSHES HAVE LOST ALL LUBRICATION, AND THEREFORE THE MOTOR CURRENT IS EXCESSIVE.
Open the bonnet. Remove the wiper arms by lifting the light-weight plastic cover from the base of the wiper arm. This cover will rotate a little, pivoted under the lower arm articulation pivot pin, and can carefully be rotated and possibly removed: (do not force), to allow access to the 13 millimetre A/F nuts which lock the wiper arms onto their knurled drive shafts. By lifting the wiper arm to 90 degrees from the base and careful wriggling, with assistance of a wide flat-bladed screwdriver if necessary, the wiper arms can be lifted away.
Remove the plastic grille valance for the fresh air intake, just forward of the front window, (windscreen in Australia), which is 3 to 4 "Phillips" head screws. Note that the washer nozzles will separate from beneath these grilles. Next remove the metal upper valance which supported the plastic grille. There are about 7 screws, (also Phillips head). which are accessed at the top of the engine bay rear bulkhead from the engine bay, which are horizontal and inset into the firewall's rubber insulation, and two or three, (I think), at the base of the windscreen.
Lift the rear engine-bay-bulkhead-(firewall in the USA?)-rubber-seal, (which prevents engine-bay fumes from entering the fresh air intake), up and away from the rear bulkhead. The air intake valance may not have moved since the car was built, so it may take some minor prising of the gap between the matt-black valance and the body-coloured bulkhead. Several old plain bladed table knives are ideal to ensure separation of any "glue-together" of the two metal parts.
The fresh-air valance will have limited "lift-away" ability because the washer hoses protrude through it. It may be possible if there is enough washer hose to lay the valance on the base of the windscreen to allow access to the fresh-air plenum chamber, but if not, disconnect the washer hoses to allow removal.
The fan motor is housed in a nearly fully enclosed, 2-piece, black plastic housing, the top and bottom parts of which have interlocking plastic male/female edges, and are held together by 2 radiator-hose-style-clamps of about 4-5 inches diameter.
BEFORE TOUCHING THESE, CHECK HOW THE DRUM FAN BLADES ROTATE, AS YOU CAN GET MINOR ACCESS VIA THE CENTRAL PART OF THE FAN ASSEMBLY. If the blades are free but "scratchy", check to see if the electric motor will run at full speed "4" with assistance to "start".
This process will check the electrical integrity of the switch/wiring.
INSIDE THE HOUSING, THE PART THAT YOU WILL BE REPLACING CONSISTS OF A CENTRAL, CYLINDRICAL MOTOR, WITH A CENTRAL AXIS OUTPUT SHAFT AT EACH END, WITH NYLON "DRUM"-FAN ASSEMBLIES AT EACH END, which cannot be disassembled or serviced, although if cost is absolutely critical, and the motor shaft is "free" but with scratchy bushes, soaking some engine-oil of 10/30 SAE may provide a year or two of extra life, but I strongly recommend a brand-new replacement fan, as its presence and good operation is vital to interior comfort for air-cond. and demisting. The original fan has lasted for over 20 years. My experience with 2nd hand fans is that they are likely to be in their last several years-of-life, and so are not worth having to do this fiddly job again.
Once you have decided that the fan must be replaced, undo the clamps and separate the top half of the fan/motor housing. This is NOT OBVIOUS, and it is useful to know that the split is roughly horizontal dipping towards the front of the car at about 30 degrees below the horizontal. There are air intake grilles at each end of the fan housing, which are separate from the top and bottom major parts, but which lock into place between them.
Having separated the top and bottom main parts of the housing, remove the grilles. Getting the top housing out of the air-intake compartment,(plenum chamber in BMW-speak), is awkward, and may require some force, far beyond what "feels right", and bending/distortion of this housing to get it out between the base of the windscreen and the engine bulkhead. I'm not sure if there is room to locate the top housing away to the right hand side of the plenum chamber, therefore removing the need to extract the top housing from the plenum area, but removal provides more working space.
Next lift the motor/fan out of the base of the housing, which will be left in place to accept the replacement motor.
GETTING THE OLD MOTOR/FAN ASSEMBLY OUT OF THE "NOT-LARGE-ENOUGH" GAP BETWEEN THE WINDSCREEN BASE AND THE FIREWALL REQUIRES PATIENT LOCATION TO FIND THE BEST EXIT SPACE, AND CONSIDERABLE FORCE MUST BE EXERTED ON THE DELICATE AND BALANCED (OBSERVE THAT SOME FAN DRUM BADES ARE FITTED WITH HARDENED STEEL LOCK-ON CLIPS, WHICH MUST NOT BE DISTURBED) FAN UNITS.
CONTRARY TO YOUR EXPECTATION THAT SUCH DISTORTION IS LIKELY TO BREAK BLADES, I HAVEN'T YET HAD ONE FRACTURE. THE NEW DRUM FANS ALSO REQUIRE THE SAME, JUDICIOUS FORCE TO RE-INSTALL, BUT THE NEW AND MORE FLEXIBLE NYLON ON THE NEW ASSEMBLY MAKES THIS SOMEWHAT EASIER, BUT STILL PROVOKES UNEASINESS ABOUT THE FORCE NEEDED.
Once the new fan/motor is in the plenum and has been located in the housing base, and reconnected to the wiring loom, CHECK THAT THE FAN BLADES ROTATE FREELY. IF THEY DO NOT, YOU HAVE NOT CORRECTLY ALIGNED THE MOTOR INTO THE HOUSING. Relocate and check free fan rotation.
Insert the end grilles. Get the upper housing back into the plenum, and with much care, ensure that all the male/female joining edges have correctly engaged. Lightly reinstall the housing clamps, AND CHECK FREE ROTATION OF THE FAN DRUMS. iF NOT FREE, SOME PART OF YOUR REINSTALLATION IS NOT CORRECTLY ALIGNED. Rectify and final check free rotation. tighten the clamps, and check free rotation again.
Operate the fan under the vehicle's battery power as a final check.
After ensuring that the washer connections are remade,(and it is wise to check washer operation prior to reassembly), replace the plenum chamber valance, ensuing that the nylon or "speednut" (speednuts are hardened screw receptacles clips) fitted to the front edge of the valance are all correctly located. It can be a tight fit to relocate this valance, and the plain knife blades are useful to guide the two metal edges past each other to alignment. Re-install all locating screws to the valance.
Re-install the air intake grilles, noting that at the centre, one side overlaps the other. Prior to screwing the grilles tight, check the squirt pattern of the washers, as some considerable adjustment within the washer jet housings in these grilles is available.
Re-install the wiper arms, and prior to final tightening of the 13mm nuts, check that there is enough central overlap of the wiper paths so that you do not get a central "dribble" of washer fluid after a wash/wipe action, which will occur if there is not complete overlap, which must still be there at slow wiper speed.
I have a friend whose '81 733i may need the fan/blower motor replaced, speaks of a burning smell last time she turned it on (has not turned it on since...).
I want to help her out, have rebuilt several heater boxes for BMW 02s, not familiar with E23s.
Looking for advice: how difficult is it to replace the blower motor in her 733i, she has A/C (I suppose they all do).
TIA
Scott E23 BMW 7 Series, 1977-1986 fresh air fan/motor replacement.
Scott, this is a 2-3 hour job to change the fan-motor over.
FIRST CHECK THE FUSES, WHICH ARE IN A CLEAR-LIDDED COMPARTMENT IN THE CENTRAL LEFT HAND SIDE OF THE ENGINE BAY.
The European open ceramic centred fuses with an outer metal fuse link are subject to external corrosion. All of the fuses in BMWs of this era should be changed every 3-4 years, to reduce the resistance at each end of the fuse body to "fuse-holder" connection.
As a first step, rotate all of the fuses in their fuse holders, with the idea of abrading away any corrosion between the metal parts to get the lowest possible resistance. This should be a standard maintenance procedure every 6-12 months. If the fuse link is sitting proud (away from) the ceramic body, this is an indication of excessive heat, which could be local to the fuse because of poor connection to the fuse-holder ends. OR BECAUSE THE MOTOR BUSHES HAVE LOST ALL LUBRICATION, AND THEREFORE THE MOTOR CURRENT IS EXCESSIVE.
Open the bonnet. Remove the wiper arms by lifting the light-weight plastic cover from the base of the wiper arm. This cover will rotate a little, pivoted under the lower arm articulation pivot pin, and can carefully be rotated and possibly removed: (do not force), to allow access to the 13 millimetre A/F nuts which lock the wiper arms onto their knurled drive shafts. By lifting the wiper arm to 90 degrees from the base and careful wriggling, with assistance of a wide flat-bladed screwdriver if necessary, the wiper arms can be lifted away.
Remove the plastic grille valance for the fresh air intake, just forward of the front window, (windscreen in Australia), which is 3 to 4 "Phillips" head screws. Note that the washer nozzles will separate from beneath these grilles. Next remove the metal upper valance which supported the plastic grille. There are about 7 screws, (also Phillips head). which are accessed at the top of the engine bay rear bulkhead from the engine bay, which are horizontal and inset into the firewall's rubber insulation, and two or three, (I think), at the base of the windscreen.
Lift the rear engine-bay-bulkhead-(firewall in the USA?)-rubber-seal, (which prevents engine-bay fumes from entering the fresh air intake), up and away from the rear bulkhead. The air intake valance may not have moved since the car was built, so it may take some minor prising of the gap between the matt-black valance and the body-coloured bulkhead. Several old plain bladed table knives are ideal to ensure separation of any "glue-together" of the two metal parts.
The fresh-air valance will have limited "lift-away" ability because the washer hoses protrude through it. It may be possible if there is enough washer hose to lay the valance on the base of the windscreen to allow access to the fresh-air plenum chamber, but if not, disconnect the washer hoses to allow removal.
The fan motor is housed in a nearly fully enclosed, 2-piece, black plastic housing, the top and bottom parts of which have interlocking plastic male/female edges, and are held together by 2 radiator-hose-style-clamps of about 4-5 inches diameter.
BEFORE TOUCHING THESE, CHECK HOW THE DRUM FAN BLADES ROTATE, AS YOU CAN GET MINOR ACCESS VIA THE CENTRAL PART OF THE FAN ASSEMBLY. If the blades are free but "scratchy", check to see if the electric motor will run at full speed "4" with assistance to "start".
This process will check the electrical integrity of the switch/wiring.
INSIDE THE HOUSING, THE PART THAT YOU WILL BE REPLACING CONSISTS OF A CENTRAL, CYLINDRICAL MOTOR, WITH A CENTRAL AXIS OUTPUT SHAFT AT EACH END, WITH NYLON "DRUM"-FAN ASSEMBLIES AT EACH END, which cannot be disassembled or serviced, although if cost is absolutely critical, and the motor shaft is "free" but with scratchy bushes, soaking some engine-oil of 10/30 SAE may provide a year or two of extra life, but I strongly recommend a brand-new replacement fan, as its presence and good operation is vital to interior comfort for air-cond. and demisting. The original fan has lasted for over 20 years. My experience with 2nd hand fans is that they are likely to be in their last several years-of-life, and so are not worth having to do this fiddly job again.
Once you have decided that the fan must be replaced, undo the clamps and separate the top half of the fan/motor housing. This is NOT OBVIOUS, and it is useful to know that the split is roughly horizontal dipping towards the front of the car at about 30 degrees below the horizontal. There are air intake grilles at each end of the fan housing, which are separate from the top and bottom major parts, but which lock into place between them.
Having separated the top and bottom main parts of the housing, remove the grilles. Getting the top housing out of the air-intake compartment,(plenum chamber in BMW-speak), is awkward, and may require some force, far beyond what "feels right", and bending/distortion of this housing to get it out between the base of the windscreen and the engine bulkhead. I'm not sure if there is room to locate the top housing away to the right hand side of the plenum chamber, therefore removing the need to extract the top housing from the plenum area, but removal provides more working space.
Next lift the motor/fan out of the base of the housing, which will be left in place to accept the replacement motor.
GETTING THE OLD MOTOR/FAN ASSEMBLY OUT OF THE "NOT-LARGE-ENOUGH" GAP BETWEEN THE WINDSCREEN BASE AND THE FIREWALL REQUIRES PATIENT LOCATION TO FIND THE BEST EXIT SPACE, AND CONSIDERABLE FORCE MUST BE EXERTED ON THE DELICATE AND BALANCED (OBSERVE THAT SOME FAN DRUM BADES ARE FITTED WITH HARDENED STEEL LOCK-ON CLIPS, WHICH MUST NOT BE DISTURBED) FAN UNITS.
CONTRARY TO YOUR EXPECTATION THAT SUCH DISTORTION IS LIKELY TO BREAK BLADES, I HAVEN'T YET HAD ONE FRACTURE. THE NEW DRUM FANS ALSO REQUIRE THE SAME, JUDICIOUS FORCE TO RE-INSTALL, BUT THE NEW AND MORE FLEXIBLE NYLON ON THE NEW ASSEMBLY MAKES THIS SOMEWHAT EASIER, BUT STILL PROVOKES UNEASINESS ABOUT THE FORCE NEEDED.
Once the new fan/motor is in the plenum and has been located in the housing base, and reconnected to the wiring loom, CHECK THAT THE FAN BLADES ROTATE FREELY. IF THEY DO NOT, YOU HAVE NOT CORRECTLY ALIGNED THE MOTOR INTO THE HOUSING. Relocate and check free fan rotation.
Insert the end grilles. Get the upper housing back into the plenum, and with much care, ensure that all the male/female joining edges have correctly engaged. Lightly reinstall the housing clamps, AND CHECK FREE ROTATION OF THE FAN DRUMS. iF NOT FREE, SOME PART OF YOUR REINSTALLATION IS NOT CORRECTLY ALIGNED. Rectify and final check free rotation. tighten the clamps, and check free rotation again.
Operate the fan under the vehicle's battery power as a final check.
After ensuring that the washer connections are remade,(and it is wise to check washer operation prior to reassembly), replace the plenum chamber valance, ensuing that the nylon or "speednut" (speednuts are hardened screw receptacles clips) fitted to the front edge of the valance are all correctly located. It can be a tight fit to relocate this valance, and the plain knife blades are useful to guide the two metal edges past each other to alignment. Re-install all locating screws to the valance.
Re-install the air intake grilles, noting that at the centre, one side overlaps the other. Prior to screwing the grilles tight, check the squirt pattern of the washers, as some considerable adjustment within the washer jet housings in these grilles is available.
Re-install the wiper arms, and prior to final tightening of the 13mm nuts, check that there is enough central overlap of the wiper paths so that you do not get a central "dribble" of washer fluid after a wash/wipe action, which will occur if there is not complete overlap, which must still be there at slow wiper speed.
Automotive Network, Inc., Copyright ©2026