RunInColorado

My brother, while driving a 1989 300TE with 100k on it, noticed a rumble/gurgle comming from what he described was either behind the climate control and radio or below the gear selector. He said this occured only for a couple of min while the car was in D and there was light acceleration on a neighborhood street with speed humps. My other brother who was riding with him got out of the car and walked along side listening for the noise but he could not hear anything from outside the car. There did not seem to be any problem with the car shifting gears or accelerating. The car was low on oil and had some added yesterday (1qt). On occasion while the climate control is turned on there is a gurgle/bubbling sound that is emitted from the vents (sounds like bubbles in a fishtank), however, the climate control was turned off and this sounded much different. I am stumped on what could be causing this sound and if it means something bad is about to happen (ie transmission going)

Anyone have suggestions?

Thanks in advance.

Diesel

https://mbworld.org/forums/showthrea...threadid=57300

RunInColorado

Thanks for your help, sounds like that is the issue when the climate control is on. However, this occured with the climate control off and sounded much different. Its an older car and I think it is a lemon when compared to the other Mercedes I have experience with. I just hope its not a signal of a costly repair!

mhorn

There is a tray underneath the evaporater core that catches the condensation from the evaporater coil while the a/c compressor is on. This tray is drained by two rubber tubes that exit under the car near the transmission housing I believe. Over time these drains can become clogged up with gunk. You can unclog them by taking an old speedometer cable or a "snake" for clogged drains and clearing them out from underneath the car. If you get water leaking from your vents and collecting under your floor mats, this is probably the cause.

Rafael Grullón

Are you ok with coolant level?
Check your expansion tank cap. When it is bad some bubbles form in the system when the car is turned off or low rpm. This could be the sound.

RunInColorado

The car was low in coolant, and I added some, it took about 4-5 cups of coolant. The cap looks good but if I hear the sound I will replace it. As for the drains, I will work on it this weekend as the car is going to VA for a couple of days and I will have a chance to drive it on the interstate.

Thanks again for everyones input. I will let you know if it is fixed.

Michael

Benzonator

I believe I may be having the same issue on my 2010 C 300 Sport. It gurgles upon acceleration, but only when the car has reached its normal operating temperature. And it happens whether the A/C is on or not. My mechanic plans to replace the control arm bushings once the parts come in on April 11. I don't know if that's the source of the problem and, frankly, neither does he.

Saijin_Naib

My 300ce does that, my Dad informed me that I've air bubbles in the heater core. Apparently, the way to get rid of it is to HIGHLY elevate the front end, uncap the radiatior, and run the car for a while until it stops. Then, top up the fluid, do it again, and finally put the car back down to see if it has been solved.

I'll tell you, 4 2x4 boards stacked on top of one another is not enough angle to get the air out, so I don't know what to tell you haha.

HAL STEINER

put your car on a lift and check your front flex joint,

Benzonator

Very intriguing, Hal. I would have never thought of that. And it makes sense, as it's part of the exhaust system, if I'm not mistaken, and the noise I'm hearing really does sound like a combination of an exhaust leak and air trapped in the heater core. I'll have MB take a look at it. Thanks!