Is this a gurgle noise or a noise like water slowly sloshing from one side of dash to the other.Sounds like the inside of the dash has a water tank in it and the water sound goes from one side to the other some what slowly.Both of my 1990 coupes had the same noise and only at times.Just when the car felt like it.The noise could not be made to happen,did it only when the car wanted to.
Both cars did not leak and never had a problem with the noise.Radio fixed it
Thanks
Rich

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88 300E White, sold 9-04
88 190E Black 2.3 sold
90 300CE White, Grey sold 12-24-04
92 400E White,Grey Sold 5-06
90 300CE 91K Signal Red,Black Sold 2007
1989 300CE Smoke silver,Tan Sold 1-08
1993 300E 3.2 M104 motor
1991 300CE White,Grey
1994 E420 beautiful car,gone to new home
1994 E320 Smoke an Parchment.Beautiful car