Ok, here I go with another lame rookie question. Bear with me.

My '98 C280 has started making a strange low level noise. I first noticed a slight "whistle" effect when I first start the car. Now, I hear it until I get the car moving. At first, I thought the noise was bearings going bad somewhere near the front and I should be able to hear it louder from outside the car. No dice. I can't seem to hear it when I am standing outside the car. Of course, it could be my old ears causing this. With an older American car, I would have thought it was something to do with the heater blower motor? Right now it sounds like a cross between a low level whistle and a squeak. It doesn't get louder when I increase the engine speed. After I put it in gear and start to move, I don't notice it. I believe this is because of the increase in ambient noise. If the car is at idle and I turn the fan motor totally off, I don't seem to hear it. When I bring the fan speed up two increments is where I hear it the most. More speed than that increases the ambient noise level to where I can't seem to hear it.

Is this a common problem with the fan motors?

Thoughts?

If one of your dash vents is ALMOST closed, it will make a whistle noise.

__________________
2007 C 230 Sport.

Cabin filter might also have an effect. You could experiment by removing it and see if the noise changes or just replace it.

__________________
1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra

I replaced the filter about 4 months ago, but it wasn't an activated charcoal filter. I have one now, so I will replace it tonight and see if it helps.

Dash vents are full open and problem still exists! Thanks for the input!

Ok, I have decided that it is the blower motor. How hard is it to get to the motor?

blower motor change is easy, under passenger side dash.

remove black plastic panel

remove wiring plug

remove blower

remove regulator bolted to blower

if you move carpeting forward to make room place a towel on floor so if you drop any screws they don't fall into nether regions of floor.

before you order a new blower, remove old one along with cabin filter, clean everything, let a little trans fluid soak overnight into top of blower motor spindel, then connect back up.

I did the above about a month back, it cured a blower speed related noise I was getting.

That sounds great! Thanks so much for the info and advice! These MBs scare me sometimes because they are so different from anything I have owned before.

I think I am going to remove it and power it up on the bench to see for sure if it makes this noise. I am almost 100% sure that is the problem because I can make it happen by varying the speed of the blower.

Either way, I am going to lube it and run it on the bench for awhile to make sure it is ok.

Thanks again!

Curt

the blower motor is held in by four Torx screw the regulator by two.
I let the trans fluid soak for at least 24 hrs before turning it on.

The blower motor is on top of the footwell so have good lighting and be prepared to do a slight contort to reac things.

Is it behind the mounting for the filter? I remember changing the filter and that housing is a trick to do while lying on your back in the floorboard!

Curt

to the right of the cabin filter is a black panel approx 7 inches by seven inches slightly irregularly shaped, you'll see a wired plug-in connection that is fitted through the panel to the regulator - it pulls out. Should be two white clips that are pushed toward one other to release panel. This is completely different than the narrow panel used for the cabin filter.

if you push the passenger seat all the way back and put a pillow over the car door sill you can lay in there. Tough to get both shoulders into the footwell to use a ratchet socket wrench so try to use screwdriver handles for Torx or just a ratchet extension acting as a screw driver.

If you have a digital camera, once you take the plastic black covering off the blower motor, shoot some picture so you know how the motor and regulator fit back into their space.

Also one you have the blower motor out, use some Lysol spray on a towel to clean ducting and parts

I appreciate such detail, as I am an obsessive, compulsive! ha ha! I will try and make some digital pics of the whole process so I know how to reattach everything. Can I post them here?

Also, I read in the archives that the motor voltage regulator has a sort of "heatsink" attachment to the motor. So I may need to freshen the heatsink grease before I reattach it?

Curt

no heatsink grease, this is ducting for HVAC so they are cautious of fumes that might arise from anything heated. That is why be cautious with the trans fluid for lubing the spindel. Let it soak in for a day or so then wipe off the excess.

Very good information! I hadn't thought of this! I definitely will be careful. I am also going to replace the filter with an activated charcoal one while I am at it.

Curt

My thanks goes out to all the guys who gave me input on this little project. I removed the motor housing and regulator. I "soaked" the shaft/bearing/bushing with tran fluid. I blew out the motor assembly (and it WAS dirty!) and cleaned all the housing with Lysol. I then replaced the filter with an activated charcoal filter. Reassembled it and tested great!

One final question: The brushes on the blower motor looked VERY worn. Can I get these anywhere, or will I have to find some "close" and then grind them down to fit? I really would like to replace mine SOON! (for a W202 - 98 C280)

Thanks again!



A couple of days later ...
That noise is back, although it is very faint. I am thinking it may be from the brushes? I am still trying to find brush replacements, either exact or close enough to grind down. Any resources for these in the Dallas area?