Strange Noise - BMW Forum

RedlinedRU · 12-27-2004, 07:18 PM

hey, my e36 started making a strange noise when it warms up. you can only hear it when you are at idle, and with the stereo off because it isn't loud at all. the only way i can describe it is that every 7 seconds or so, it makes a slight "umph" noise almost like a small pump was turning on, or a bubble in a fluid resovoir was being popped. its hard to describe, and doesn't happen when engine is cold. the computer says everything is fine, but this is bothering me b/c it wasn't doing it before. thanks in advance for any help. N

bigred318 · 12-27-2004, 08:08 PM

maybe try to get a clip of it.. i have never personally heard this before, also it would help if you could locate what side of the engine etc... pop the hood and listen

David

Linds · 12-27-2004, 09:45 PM

I have the exact same noise in my car (99 323is). Maybe it's a problem with these similar years/models. The only thing that is different about mine is that sometimes it's a double pop. Kind of sounds like a heartbeat...really weird.

If you find out what it is let me know.

RedlinedRU · 12-28-2004, 10:06 AM

hmm, thats crazy. if/when I find out, i will let you all know for sure. You're right, it does sound more like a pop, than anything else.

frank3 · 12-28-2004, 12:15 PM

Where is the noise coming from? Could it be the noise of some vacuum mechanism kicking in, like the heater directional doors behind the dash that shift the heat from feet to defrost? If this is it and it's recurring, then you have some sort of minor vacuum leak that causes the door to keep closing at low idle (but disappears at higher vacuum levels).

This is a total guess...knowing where the noise comes from will help pinpoint.

RedlinedRU · 12-31-2004, 12:37 PM

that may well be what it is.....considering it didn't do it in the fall when I didn't have the heater running. its a very hard noise to pinpoint, but it sounds like its very close to the firewall somewhere.

Tiny2u · 12-07-2005, 08:14 PM

Can anyone help me out with this problem.. my 97 328i is making this same "heartbeat" noise when idling at temp.

Is it serious? i really don't want to take it to the stealer and i just moved to RI so i don't trust anyone else.

Anyone?

drz · 12-07-2005, 08:38 PM

It sounds to me like it is the heater valve. I sits right in front of the driver's seat. I describe it as a cyclical clicking. I was once able to stop and follow the noise. I followed it to the heater valve, where I could feel the vibration coming synchronously with the noise. I purchased a replacement, but have not yet put it in. I have had this situation going since the late summer. I will be putting in the new valve in the next couple of weeks.

I hope this helps.

bimmerboy328i · 12-07-2005, 08:48 PM

Quote:

Originally Posted by drz

It sounds to me like it is the heater valve. I sits right in front of the driver's seat. I describe it as a cyclical clicking. I was once able to stop and follow the noise. I followed it to the heater valve, where I could feel the vibration coming synchronously with the noise. I purchased a replacement, but have not yet put it in. I have had this situation going since the late summer. I will be putting in the new valve in the next couple of weeks.

I hope this helps.

That is exactly what it is.

Tiny2u · 12-09-2005, 02:04 PM

Thanks guys, Is this a major thing of is it something i can let go for awhile? What caused it to break?

Also, is this a DIY job or am i going to have to take it to the stealer?

kyle_baker · 12-11-2005, 12:21 PM

probably not a major deal, but it will continue to annoy you, lol, so all depends on how long you can handle the noise. personally i try to fix all little annoyances like that asap, but it really isn't that big of a deal

i think drz is saying it is a DIY, i'm sure he will share some instructions for you once he finishes replacing his.

victorgallas · 12-15-2005, 12:46 PM

Quote:

Originally Posted by frank3

Where is the noise coming from? Could it be the noise of some vacuum mechanism kicking in, like the heater directional doors behind the dash that shift the heat from feet to defrost? If this is it and it's recurring, then you have some sort of minor vacuum leak that causes the door to keep closing at low idle (but disappears at higher vacuum levels).

This is a total guess...knowing where the noise comes from will help pinpoint.

Hey i just wanted to clarify something about BMW's ac systems.

They do not use vacuum lines and actuators to move vent flaps, this is done electrically by means of servo motors.

The early e36 with rotary selectors have 3 servoe motors.
The electronic unists use 5 servo motors.
they are small round, flat bosch unit.

What can happen to them after a while is that they get dirty inside and so they dont give their position reading properly to the ac computer. to fix it take the motor out, is normally clipped in, then carefully open the back cover and using electronic spray cleaner clean the all the electronic contacts..

this will help the electrical, and if you want to lube a little bid any mechanical parts, dont go too crazy on the lube as this will rather make its way back to the elctronics on hot days.

well this is just my input.

about the clicking noise, it is the heater valve.
its a doul solenoic unit and the cycles is the way the ac ecu control the heat input to the heater core by Pulse With Modulation. By changing the time that valve stays open the ecu can control how much fluid goes into the heater core therefore controling heat temperature.

I found out that after a while this valve get a little sticky and so they make noise when moving, you can replace it or just live with it..

well have a good one.

victor