Sloshing Liquid Behind Dash
 

I've got this new sound.... when I turn on the engine, for maybe 5 seconds after, I hear a liquid sloshing sound from behind the center of the dash. There's nothing leaking inside - or outside. The heater does produce good hot air. I am thinking this is coolant in the heater core, but why am I hearing this? Tonight I started it with the heat on and I think it sounded less. And I never hear this while the car is running while driving.

Have you checked your coolant level? Is it low?

You may have water in the cowl area because the drains are clogged and need to be cleaned. Here's a couple of links about it ...

https://themustangsource.com/f637/co...r-leak-522473/

https://themustangsource.com/f637/fi...boards-469258/

Well, I did check the tank and it was low. Filled it back to the cold range and so far haven't heard it.

On a related note, I was looking at the inside of my coolant tank and there's no shortage of gunk on the walls. What's the best way or easiest way to clean it? It didn't come off when it became submerged in coolant again but I just don't like seeing it. And I wouldn't want some to come off the plastic and get carried around in the coolant to plug up something. Kind of like how you don't want plaque coming off your arteries in your blood and causing a stroke!

have you noticed the passenger side floor under the mat if it is wet ? when I have my mat down drive intowork it the am then check under before I head home it's damp ??? but when I leave the mat up it always seems to be dry. So I'm not sure if it's coimig in from the cabin polin air filter on the passenger side firewall , it's not the heater core as no smell and my coolent is full .

No, haven't had that lately. But there are a million threads about the dreaded water leak in these cars coming from the passenger side. In fact, i had that a couple years ago. The dealer tried fixing it but I had it once again, and then later suddenly it stopped happening. I don't know what it was. I still keep checking the carpet after every heavy rain. It was leaking right onto my junction box behind the kick panel and it corroded the connector terminals for the power mirrors, so they replaced the whole junction box. Passenger side water leak is a VERY common (and serious!) complaint on the '05-'09 models.

I had never known that I may have tip take apart my passenger side to figure it out