Water sounds behind dashboard

All of a sudden my 99 Prerunner is making water noises behind the dash upon startup. Even with A/C off it does it

 

Check your cooling system, low coolant can cause this, you might have a leak...

 

My first thought is that the seal around your windshield is bad. Could actually have water behind your dash. You can test this with a water hose. Put it up on the seal around your windshield and see if you can see any leaks.

 

x2 on the low coolant, your prolly hearing the coolant rushing through the heater core

 

Maybe the coolant system has trapped air, and needs to be bled.

 

That doesn't happen on it's own, I think he has a coolant leak that needs to be found and repaired!

 

I wonder if the A/C drain coming out of the firewall is plugged and now filled the air box under the dash with water.

 

when you say water noise..do you mean like splashing? or moving through pipes?

 

I agree, likely neglected maintenance.

 

It is a '99, parts do wear out with time...

 

Coolant.

 

Moving through pipes

 

what these guys said. there's nothing for water to puddle in under the dash that would cause any noise. check level and burp the system.

 

have you looked inside the cowling vents? if the drain in there gets clogged up its like a bucket of water that sloshes when you turn or hit brakes.

ifthe a/c drainis draining and running it is not related to when you hear the noise, its water build up in the cowling unable to drain off as it should

 

OP, did you ever find out what this noise was?

 

Not OP but I had a similar noise after doing a coolant flush. It sounded like water pulsating through a pipe. Is that what you’re experiencing?

 

If the truck is standing still how can water slush around? Low coolant more than likely.

 

Coolant can make some noise going through the pipes. It might not happen if your heat is set to cold and/or your fan is off. I noticed it after doing a coolant flush. idk if it did it before.

 

Mine just sounds like water sloshing under my windshield, It only happens when i’m driving during or after heavy rain. I’m thinking my cowl vent may be stopped up where water can’t drain like it’s supposed to.

 

Did you check the evap drain box? It might be full of water because the drain (coming out/through the firewall) is clogged.