Sloshing sound on cold startup - 2005, 146,000miles

[dwulffusa]

Hi

My 2005 began making this sound over the past three weeks.

Upon cold start, after standing at least 1-2hours, there is a liquid/water slushing sound that appears to come from behind the instrument cluster. It lasts 1-3 seconds, it occurs with or without AC on. I cannot replicate it after it has been started once.
The vehicle was serviced last week (full service) and AC re-gassed. I did mention it at service though nothing was identified.

Last night I let it idle for a while after driving for 45minutes and heard the sound again for a few seconds, though muted.

Anyone else experience this?

Thanks

 

[fdbyrne]

It's air in your coolant system that is accumulating in your heater core. When the water pump kicks on it pushes fluid into the heater core which is only partially full at that point thanks to an air bubble.

It's relatively common (not normal, but not unheard of either) and can be caused by a number of different things. Some serious (like a head gasket) and others not at all serious (a recent coolant change where the air wasn't completely purged).

Mine does it too.

 

[dwulffusa]

It's air in your coolant system that is accumulating in your heater core. When the water pump kicks on it pushes fluid into the heater core which is only partially full at that point thanks to an air bubble.

It's relatively common (not normal, but not unheard of either) and can be caused by a number of different things. Some serious (like a head gasket) and others not at all serious (a recent coolant change where the air wasn't completely purged).

Mine does it too.

Thanks. So if my coolant level isn't decreasing, its probably not a head gasket? Is bleeding the air bubble out a simple job or needs another visit to the dealer?
If the heater core is packing up, would it ever leak fluid into the car (I know this can happen on some vehicles depending on where the heater core is).
Is it anything to worry about at this time if not losing any coolant?
Should I run the heater occasionally?... Living in SoCal, it is never used.

 

[bergs]

Probably makes no sense based on your description but make sure the blower box drain is not clogged.

I diagnosed water in my blower box by making a continuous and deliberate left hand turn while the blower was running. If you hear the noise described, your drain is clogged.

The location of the drain is on the passenger side lower area of the fire wall in the engine bay, a ~3/8" diameter tube about 3" long.

Drained maybe 1/2 gallon from mine.

 

[fdbyrne]

I don't have all the answers to those questions, unfortunately. I don't think that the problem is usually with the heater core itself. I believe that it's just the high point in the system and therefor it's where the air gathers when the vehicle sits. If it's actually cracked, it can leak coolant into the interior. That has happened to people, but I don't think that the sound is any kind of predictor that that is going to happen.

You can burp the system by lifting the front off of the ground as high as you can, removing the radiator cap, and letting the engine warm up to the point where the thermostat opens. You should see air bubbles.

I've been told that these engines are hard to get all the air out of, but I have no idea whether or not that's true or just what a lazy mechanic says when people ask why their truck is making that sound after a coolant change.

Mine has been doing it for the last year (10,000 miles) and hasn't gotten any worse and runs fine. Sure, I'd like for it to go away but I'm not willing to throw money at it when it doesn't seem to be causing any problems.