I searched but didn't exactly find anything, but if anyone has asked this before and started a thread it'd be appreciated. Here we go. I've been hearing this fluid sound when accelerating or turning that sounds like its coming from the passenger side under the dash. I thought at first it might be the heater core, but the passenger side floorboard doesn't feel wet at all. Any ideas what it could be?

 

Air bubbles in your heater core maybe? There are nothing behind there other than the heater core that would make a "fluide noise". If there is a leak, it don't have to drip down on the floor. It could be so small of a leak that it stays inside the heater box. Any coolant smell or fog on the inside of the windows with the defroster on? Those are both signs of a coolant leak.

 

From what I think I read from another thread on this issue, this could be caused by air bubbles. I don't know what will get rid of it, but you could try flushing the heater core.

I just hope you aren't apart of the No-Heat Blazer club of Florida, lol. It sucks on those few cold, but many humid mornings.

I know I'm not much help, but I have never had this issue. Then again, I've also never had heat.

 

Thanks for the responses guys. I have no smell of coolant or any other odors in the cabin. I am going to look into how to drain the heater core and hopefully try that next weekend. That would make sense though since I didn't start noticing this sound until a week or two ago. And I only really hear it if I run the heater or ac.

 

Had the exact same problem with my 96. Used some radiator flush to flush it and problem was solved. I also read on here some where to put the front end on ramps and run it with the cap off, adding fluid till it is full. Not sure if that works or not. The flush thing worked for me.

 

A heater core with air in it tends to have a bubbling/boiling sound, not a sloshing/splashing sound. The heater core is is series with the radiator... is the rad full? Also, I have seen water collect in the fresh air vent intake that are at the top of the hood/lower windshield. There are drains in there that can become clogged. so when water goes in with the air, it cannot drain out, so when the truck moves around, so does the water. Stand outside on the side truck near the windshield and aggressively rock the truck side to side... can you hear anything?

 

It can also be caused by a bad radiator cap. Make sure yours is clean and serviceable. If not, I suggest replacing the rad cap.

 

I had a fluid sound like you describe on my '95. I had recently done a water pump replacement, filled the radiator and reservoir, but forgot to top off the reservoir after running it. I topped it off and haven't had the sound since. I'd check for leaks and check the level in your reservoir as a starting point.

 

Checked for leaks today, its still full from when I filled it up after putting a new thermostat; in all honesty it could use maybe three caps of dexcool/water mix to get the resivoir back to 100% full. Tomorrow I'm going to try to check the drains at the bottom of the windshield tomorrow. Last night I got a PO155 code so it looks like next weekend is going to involve replacing the 02. This week I'll be back to driving my Firebird.

 

run it with cap off to get the air out and get a new rad cap.
worked for me....sounds like half full 5 gal jug rocking back and forth right...mine did.
hope this helps.