I have a 1998 Mercury Grand Marquis, I'm hearing what sounds like sloshing water under my dash and it gets worse kinda quick (more water seems to build) if I use AC or have the defrost on. It's driving me crazy. What is it and what can I do about it? Thanks for the help!
Update: Replaced MAF sensor going on 2 months ago and the sloshing went away along with the old sensor. It's very weird but I will not complain since I have no issues now.
Drains for the HVAC system may be clogged. That was the case when I had a similar problem.
I'm gonna check that out but the fact I lose coolant after a while makes me think that's not it, at least not completely anyway so i will be checking that too.
Usually if the heater core is leaking you can smell coolant inside the car and and your windows will fog up with coolant vapors when using the defroster. You might want to pressure-test the cooling system.
I've noticed the windows fogging up, good to know this is a symptom.
Check your coolant level. If you have air in the system, you can have a "water sloshing" sound.
Is there any water inside the cabin/foot wells?
Have you tried flushing out your heater core? Coolant level fine & air burped out?
No water inside foot wells and I lose coolant but no leaks. My mechanic said he would have to check it out but sounds like my heater core could possibly be leaking.
I'm going to check out a few things my self but I'm really hoping it's something else other than the heater core leaking because I don't want to have to go through with that hassle.
Looking for any more information to try and get better accuracy on my actions before I do anything. Hoping maybe this occurred before in someone else's experience and it was simply a heater core flush needed or something.
Any white smoke from the exhaust (not on a cold day/morning)? I think your mechanic needs to have a thorough look at it & do a proper diagnosis, before replacing the heater core. Good luck & keep us posted.
No white smoke other than on cold days. I have done seafoam treatment and Italian tune up since buying the vehicle and it has cleaned it up very nicely I must say. But other than burning off carbon no white smoke has occured while running the vehicle after that for months now. Only issues I have right now is M.A.F sensor which I am replacing soon and this sloshing issue. And sure thing, I will keep you guys informed.
Fingers crossed & good luck.
If you're sure it's from the front then it could be the hvac drains might be clogged or heater core as been mentioned. Can't think of much else it could be under the dash.
Had a 2014 Mustang and sloshing sound and couldn't pin point it and found the door drains in both doors were clogged, had a ton of water in both. Cleared the drains and water poured out for a while.
I was driving earlier and didn't notice any sloshing, could be Hvac is main player in this sound but I'm afraid I still have a leak in my heater core causing an issue as well so it seems both matters I have to address. Thank you for the information on your experience.