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E34 (1989 - 1995)

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  #1  
Old 07-16-2016, 03:41 AM
resoLV resoLV is offline
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Location: Las Vegas
 
Join Date: Jul 2016
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Mein Auto: 1994 525I
Weird blower issue

Hey guys. So I'm having a issue that is driving me crazy. I recently acquired a 94 525i and I've been bringing it back to life within the last few weeks with basic maintenance.

First, it would overheat after 5 minutes of use. Replaced thermostat, bleed the old coolant and then refilled and bled bled bled until no air bubbles. Works like a champ now.

Oil change (oil was black ), new oil filter, spark plugs, belts. Just have to get new brake pads and the rest of the issues are purely cosmetic for the most part.

Now that's enough of that. The issue at hand... this damn blower motor. I couldn't get any air to blow through this damn sucker if my life depended on it. After doing some research, I replaces the FSU and bought a new cabin filter and replaced it. Still cannot get it to start, reliably. The only thing that manages to start up the blower motor is to hit a good bump or pot hole and voila, it starts up beautifully. Because of this, it makes me think that the motor isn't dead but perhaps a electrical issue? Please advise me on what to do next, I am a DIYER and have done all the work on this car myself. It's vegas, 115 degrees and the window breeze isn't doing it anymore.

Thanks in advance!
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  #2  
Old 07-16-2016, 07:30 AM
Mr._Graybeard Mr._Graybeard is offline
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Location: Wisconsin
 
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Mein Auto: '95 540i, E30, E24
Motor brushes are probably worn out -- a bump in the road causes them to shift, restoring their connection to the commutator and making the motor run. Then you hit another bump and the brushes shift again -- the motor stops.

Time for a new motor if that's the case.
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  #3  
Old 07-16-2016, 09:03 AM
south26 south26 is online now
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Location: Dayton, OH
 
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Mein Auto: 535i 1989
I would agree. I would suggest taking it out and double checking the 2 wires attached to the fan are tight, but good chance the fan will need to be replaced. I think I have a good used fan for 50 shipped.

Andy
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  #4  
Old 07-16-2016, 10:33 AM
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thumper600 thumper600 is offline
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Mein Auto: '95 540i M-Sport, 01 M5
are you sure a connection to the blower hasn't jimmied loose and makes sporadic contact? If yes maybe it is the brushes. I'd check the wiring first because my 95 has no issues like that at all and that blower motor has been rode hard and put up wet for the last 13 years of my ownership of the car.
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  #5  
Old 07-16-2016, 12:41 PM
ThoreauHD ThoreauHD is offline
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Mein Auto: 02/1994 530i 8cylinder
You have to replace it. $104 at rockauto. You aren't going to enjoy the installation I'm afraid.
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  #6  
Old 07-19-2016, 05:12 PM
BMW_507_4ME BMW_507_4ME is online now
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Location: Florida
 
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Mein Auto: 530i
New brushes

I had the exact problem on my 530i. I, unlike many lucky people here, and everywhere else for that matter. I thought 100 + bucks + S/H was a lot of money. I bought a set of new brushes on ebay for 10 bucks and installed them in my old blower motor. Don't know if this helps, hope it does, but if money is no object, a new blower will work too
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  #7  
Old 07-19-2016, 06:26 PM
rav31 rav31 is offline
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Mein Auto: 2001 540i/6 Tisilver/gray
Here's my .02 cents....It's my opinion, that, as these E34's age, the bearings on the blower fan shaft just dry out, grease that is. I have removed mine twice so far and lubed with some spray. It would work for awhile without any noise. However, if cold out OR very hot, the blower will make a load howling/squeal sound i position #1 & #2. I can put up to 4 (high) & it will spin enough to start spinning freer. After lubing, the noise does goes away for a while but I'm thinking that I used too light of an oil. Need to put some grease on it in hopes that it will wick into the bearing housings. I'm sure a new replacement will fix the issue but I always want to try to lube it. My car is a '92 535i 5 speed with 55k on it, so I don't think the brushes aren't worn out.
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  #8  
Old 07-19-2016, 06:52 PM
BMW_507_4ME BMW_507_4ME is online now
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Location: Florida
 
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Mein Auto: 530i
Bearing / bushing

Most all the blower motors I have dealt with are what they call "permanently lubed bushing" meaning, replace when squealing starts. In some cases you can disassemble the motor by removing some screws or rivets and get to the bushing / bearing. If so, you can clean and lube a bushing with moly grease or replace a bearing if it is a sealed bearing. This requires some skill with electric motors as you will need to retract and retain the brushes "FIRST" and re rivet if needed. Not hard to do, just need to know how to do it to not ruin the motor. I would always replace the brushes if I went this far
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  #9  
Old 07-19-2016, 08:39 PM
Mr._Graybeard Mr._Graybeard is offline
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In light of the fact that bad E34 blower motors have been blamed for car fires, I'd be careful about service to this particular motor. I did the brush job 507 suggests on a motor in a W123 Mercedes that was accessible in less than 10 minutes (under the dash) and better isolated from dead leaves and such. The E34 motor is far less accessible behind the firewall at the same time it's more exposed to the elements. If you can replace the bearings as well as the brushes, great. Clean up the commutator and you've got all the motor's wear points covered.
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  #10  
Old 07-19-2016, 09:26 PM
BMW_507_4ME BMW_507_4ME is online now
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+1

Quote:
Originally Posted by Mr._Graybeard View Post
In light of the fact that bad E34 blower motors have been blamed for car fires, I'd be careful about service to this particular motor. I did the brush job 507 suggests on a motor in a W123 Mercedes that was accessible in less than 10 minutes (under the dash) and better isolated from dead leaves and such. The E34 motor is far less accessible behind the firewall at the same time it's more exposed to the elements. If you can replace the bearings as well as the brushes, great. Clean up the commutator and you've got all the motor's wear points covered.
Good stuff, It is strange that BMW didn't think about trees and stuff when they designed the blower on e34's, and like many other stuff on BMW's, it is a PIA to get too. I hope I was clear that a novice with electric motors should just buy a new OEM one, but with a little knowledge, one can fix a OEM motor and also clean out all the crap around it. One could also buy a cheap China copy of the OEM motor for a hundred bucks and save a hundred bucks and put it in a e34 with a history of burning the car to the ground from a blower motor problem.
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  #11  
Old 07-20-2016, 07:38 AM
BMW_507_4ME BMW_507_4ME is online now
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Location: Florida
 
Join Date: Aug 2014
Posts: 68
Mein Auto: 530i
Blower motor VS Resistor

Many e34's have gone up in smoke and the blower motor was wrongly blamed for it. In fact, it is almost always the resistor that starts the fire. Here is how it works. Your e34 is getting older, you don't change the cabin filter per manufactures recommendations, and or you change it with a China copy filter for a great grate deal you got on fleabay. If is made of the most flammable cheap paper material money can buy, and it "kind of" fits like an OEM filter. Now, while laying on your back under your dash, you jam it in till you can get the cover back on. Everything is fixed and you can breath all that clean air that new filter is providing, that is till smoke starts pouring out of your dashboard. You get out alive and because these cars have some weight to them, the scraper gives you $350.00 and tows it off for Free! But add to the $350.00 the $15.00 you saved on that China filter that almost fit, and you came out OK. Or your the other guy that just leaves the old filter in place till it falls apart and leaves and stuff push the bonfire stuff up against the resistor and presto, instant heat.

Well here is the deal, it wasn't your blower motor that helped you start looking for a new car. or healing you burns in the ICU, it was your resistor. Lets take a look at how it works. Your blower motor will run a full speed IF it gets all the volts and amps from its circuit, so in order to be able to slow the fan down, you need resistance to use up some of that power. This is why when your resistor goes out, your blower still runs on high, no resistance needed on high.

Think of your resistor as kind o like the coils in a cigarette lighter and the fan speed control switch on your dashboard as a device that determines how much power goes to the blower and how much is used by the resistor, the incoming power to the switch doesn't change, just where it gets used, ie. blower / resistor. So now you turn your blower down to #1 setting, the resistor begins to glow hot and the fan slows down, next, the old filter or the new filter gets pushed too close to the cigarette lighter, I mean resistor and you have a camp fire right in your car The blower is actually running cooler and slower, but that resistor is glowing like a SOB.

Now you know why you change your cabin filter with only the correct parts and make "sure" it is in correctly, also, the slower your fan is turning, the more likely your car will start burring
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