View Full Version : Blower Rattles? Prognosis?
dauchande
05-17-2008, 11:15 PM
Once the Blower (I assume this is what I hear) begins to rattle can this still work indefinitely or do they always fail completely shortly after? Started hearing this a few weeks ago and now its pretty much a full time, all speed rattle... I also tonight believe i noticed the speed was flutucating rather wildly speeding up then slowing...
Weird, mine has started quitting when the A/C is on and the fan is switched to like the #2 setting. Moving it to the #3 setting it works fine. It doesn't seem to do that with the A/C off so I'm assuming it's somehow related to that, maybe a leak somewhere in the A/C/Heater plumbing somewhere?
I had a Volvo 240 DL that was noisy the way you describe and it never did fail all the years we owned it, dk about bimmers though.
Once the Blower (I assume this is what I hear) begins to rattle can this still work indefinitely or do they always fail completely shortly after? Started hearing this a few weeks ago and now its pretty much a full time, all speed rattle... I also tonight believe i noticed the speed was flutucating rather wildly speeding up then slowing...
They will go for a long time making noise. If you can stand it.
They will go for a long time making noise. If you can stand it.
Any idea what's causing the rattle exactly? The impellers just wearing on their axle? Replacing with another used part may not be all that smart if they all end up doing this eventually.
dauchande
05-18-2008, 05:45 PM
They will go for a long time making noise. If you can stand it.
With the experience with my Volvo, I think you'll get sick of hearing it and go ahead and fix it long before it completely fails.
With the experience with my Volvo, I think you'll get sick of hearing it and go ahead and fix it long before it completely fails.
Probably true. I am just such a huge wimp when it comes to being uncomfortable driving in the heat that its at least some relief to have some basis to trust i will probably not be forced to go without it due to sudden failure before I get a new one and install it.
The motor shaft rides in bronze bushings that wear. If the slop becomes bad enough they screech like hell and even sometimes the blower cages rub the housing. I've seen them with .030" play and still turning.
It will "function" almost indefinately but the noise will eventually get the best of you.
Zorrow
05-19-2008, 09:13 AM
Any idea what's causing the rattle exactly? The impellers just wearing on their axle? Replacing with another used part may not be all that smart if they all end up doing this eventually.
I have a '93 e34 and my blower started rattling also after a long few winters of storage. I blew the fuse now. I suspect that mice have got in and built a few condos. They always seem to get in this area for some reason. I am going to open it all up today and clean it out. My speed settings work sometimes and then cut out and last time I only had full speed--so for sure I also have to replace the motor resistor blue block--a common failure item. Will know more in a day or so.
Ferret
05-19-2008, 09:35 AM
Probably true. I am just such a huge wimp when it comes to being uncomfortable driving in the heat that its at least some relief to have some basis to trust i will probably not be forced to go without it due to sudden failure before I get a new one and install it.
Silicone spray usually clears the 'SCREEEEEEE...' noise if the bearings go noisy, however it's only a temp fix and a hell of a lot of work to strip it for a months worth of noise free operation!
Claude
05-19-2008, 12:09 PM
The motor shaft rides in bronze bushings that wear. If the slop becomes bad enough they screech like hell and even sometimes the blower cages rub the housing. I've seen them with .030" play and still turning.
It will "function" almost indefinately but the noise will eventually get the best of you.
Ross you say : It will "function" almost indefinately... Upon your experience what about the life of the brush that feed the blower motor ? what's the chance that they fail / worn out before the bushing ?
The brushes outlast the bushings. See this thread for a low cost replacement.
http://www.bimmernut.com/forum/showthread.php?t=36543&highlight=blower+motor
Silicone spray usually clears the 'SCREEEEEEE...' noise if the bearings go noisy, however it's only a temp fix and a hell of a lot of work to strip it for a months worth of noise free operation!
I wouldn't call what I hear a screech its much more like a rattle Sounds like Ross described the cause.
Zorrow
05-23-2008, 10:44 AM
I have a '93 e34 and my blower started rattling also after a long few winters of storage. I blew the fuse now. I suspect that mice have got in and built a few condos. They always seem to get in this area for some reason. I am going to open it all up today and clean it out. My speed settings work sometimes and then cut out and last time I only had full speed--so for sure I also have to replace the motor resistor blue block--a common failure item. Will know more in a day or so.
An update on my blower speed problem which is very common. I did have alot of mice condos and I vacuumed it all out. But I researched this a bit and the root problem seems to be reduced air flow across a dirty micro filter which many guys don't know they have and don't replace--it is also a hard job to get at it.
You see, the blue resistor pack to control speeds 1,2, & 3 (not full speed 4) relies on a good air flow to cool the resistor coils. With a clogged micro filter, you don't get enough flow and the built in thermo switch opens. That is why, after a few minutes when it finally cools down, you get your speeds back.
After I cleaned out my fan and filter, I had no more speed problems. But, if you are just on the verge of not enough air flow (BMW designs many things just on the verge!!), and you are lazy to change out the hard to get out filter, I tried this which works in a pinch. Take out your blue resistor pack (also not an easy job). It is located in the driver's foot well just above your foot when on the accelerator. You have to remove the bottom and side covers--it is a little tricky to get out as the air duct is attached to the bottom cover! TIP: Do not remove the center screws in this panel as they only hold on the air duct which can come off with the panel in one piece. Just remove the uppermost top left screw and the 2 black plastic quick release connectors near the floor and wiggle the whole damn thing out--slowly!
Now, take some fine sand paper and clean out the thermo switch contacts. Next, take a flat screwdriver and very carefully bend up the bottom contact a few hairs--not too much. This will put extra pressure on the thermo blade to not raise up too early (with poor air flow) and break the connection. If this doesn't work, you must change your micro filter. Don't go and buy a new resistor pack as this may not be the problem--unless you can clearly see that it has burned out. They usually don't!
By the way, you can see the famous filter at the bottom of the fan blower cage if you have this apart. I took a rubber hose and attached it to my shop vac and fished it in enough to do a good cleaning of most of the filter without removing it. My air flow shot up real nice and with the blue resistor changes my problem is now solved--for a while until the dreaded micro filter gets dirty again. Trust BMW to make these regular maintenance items so difficult to do. Is it a dealer repair conspiracy?? Or just typical German engineering obstinance that they have the perfect designs--on paper but with little regard to make maintenance easier.
Another final tip. When you remove the blue resistor pack, vacuum out the hole that it sits in--usually it is very dirty (paper, leaves, seeds, etc.) and restricts needed air flow also. This has to be clean also to not catch fire as the resistor heats up!! What a stupid BMW design!!! If you stick your finger up in here, you will feel the back side of the micro filter!!
Hope this is helpful to some of you with this very common problem--now exposed!!
Zorrow
An update on my blower speed problem which is very common. I did have alot of mice condos and I vacuumed it all out. But I researched this a bit and the root problem seems to be reduced air flow across a dirty micro filter which many guys don't know they have and don't replace--it is also a hard job to get at it.
You see, the blue resistor pack to control speeds 1,2, & 3 (not full speed 4) relies on a good air flow to cool the resistor coils. With a clogged micro filter, you don't get enough flow and the built in thermo switch opens. That is why, after a few minutes when it finally cools down, you get your speeds back.
After I cleaned out my fan and filter, I had no more speed problems. But, if you are just on the verge of not enough air flow (BMW designs many things just on the verge!!), and you are lazy to change out the hard to get out filter, I tried this which works in a pinch. Take out your blue resistor pack (also not an easy job). It is located in the driver's foot well just above your foot when on the accelerator. You have to remove the bottom and side covers--it is a little tricky to get out as the air duct is attached to the bottom cover! TIP: Do not remove the center screws in this panel as they only hold on the air duct which can come off with the panel in one piece. Just remove the uppermost top left screw and the 2 black plastic quick release connectors near the floor and wiggle the whole damn thing out--slowly!
Now, take some fine sand paper and clean out the thermo switch contacts. Next, take a flat screwdriver and very carefully bend up the bottom contact a few hairs--not too much. This will put extra pressure on the thermo blade to not raise up too early (with poor air flow) and break the connection. If this doesn't work, you must change your micro filter. Don't go and buy a new resistor pack as this may not be the problem--unless you can clearly see that it has burned out. They usually don't!
By the way, you can see the famous filter at the bottom of the fan blower cage if you have this apart. I took a rubber hose and attached it to my shop vac and fished it in enough to do a good cleaning of most of the filter without removing it. My air flow shot up real nice and with the blue resistor changes my problem is now solved--for a while until the dreaded micro filter gets dirty again. Trust BMW to make these regular maintenance items so difficult to do. Is it a dealer repair conspiracy?? Or just typical German engineering obstinance that they have the perfect designs--on paper but with little regard to make maintenance easier.
Another final tip. When you remove the blue resistor pack, vacuum out the hole that it sits in--usually it is very dirty (paper, leaves, seeds, etc.) and restricts needed air flow also. This has to be clean also to not catch fire as the resistor heats up!! What a stupid BMW design!!! If you stick your finger up in here, you will feel the back side of the micro filter!!
Hope this is helpful to some of you with this very common problem--now exposed!!
Zorrow
I occasionally smell what i recognize to be leaves and pine needles etc burning ... not very encouraging.. I will be agin replacing the Blower Motor after I buy a brand new one and at that time, when I have actualy TIME I will vacume out all that debris from both the air box and from up under the resistor. I managed to get to it and R & R it with out removing the underpanel ,just the carpet panel but believe me my poor hands were worse the wear,lol..
The Microfilter while not as easy as replacing say the Engine Air Filter really in perspective isn't that bad..The plastic panels though are easy to brake and when broken make reassembling rather tenuous but still nothing rattling or hanging down yet..lol..
Sixdown
05-31-2008, 11:40 PM
Good luck getting all the debris and dust from behind the blower. A lot of the stuff will be jammed into the metal. Replacing the fan itself is pretty easy and straight forward and be sure not to destroy clips and such, which is pretty easy to do accidentally. If I remember, you'll have to replace some zip ties that hold the wiring harness to the firewall.
Sadly, my car doesn't have a microfilter, so lots of debris can be found everywhere.
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