When I first start my '85 Trans Am up in the morning, I notice a loud sloshing sound of water and it sounds like it coming from under the dash. It has done this for a long time. Any ideas what it could be? I don't notice any leaks. It almost sounds like a washing machine.

 

It's your heater core.

You need to add coolant.

 

it could also be your over flow tank eather haveing water going into it from your radiater or water being sucked out of it from your radiater.

 

I hear the sloshing sound when the car is cold. Again, it sounds like a washing machine. You can hear the spashing sound loud. I think it could't be the coolant tank because the car is cold. The heater core could be a possibility but why would you hear it so loud? You expect water to start pouring in the floorboard any minute but after it warms up, the sound goes away. Actually I guess a dishwasher sound is closer to the sound than a washing machine, haha. Anyway, I have had people who ride to ask, what is the water sound and I have to say, I have no idea!

 

Check the cooling system to make sure its not low on coolant. Like said above, the sloshing is probably air going through the heater core.

 

I checked that before. The tank is full and the radiator is full. I think the heater core though might be where the sound is coming from now that you mention it. I just wonder why. Maybe I have it on spin cycle.

 

Just because the coolant level appears to be full, does not mean you do not have air trapped in the system. The noise you hear does sound like you have air trapped in the system. You need to purge the air from the system.

 

I think that has to be the problem. I am going to take it in and have the system flushed and tell them the problem. That sounds like air causing it. I didn't think about that. Thanks!

 

Air in system == system not full of fluid, by definition

Just because it was full whenever you checked it, doesn't mean it's full now.

Check it, make sure it's full now, before wasting money on something that isn't necessary to fix the problem and that you could do yourself anyway if you wanted to.

"The simplest explanation that fits all the facts is usually the right one".
-Occam, ancient Greek philosopher, from the days when cooling systems weren't even pressurized

 

 

aka KISS (Keep It Simple, Stupid)