850 water FLOWING sound Topic is solved

[jsrnsis]

I don't know if this deserves it's own thread, but in my 94 850, when I turn the car on, there's a flowing water sound coming from behind the dash, and I think from the heater core piping. The car has had its heater core replaced with a behr unit last year, and new o rings, and this problem only started a few months ago, and I think has been getting worse. The sound gets faster when you give it gas.



Everything I look up for water flowing behind the dash seems to be from people with plugged sunroof, cowl, or HVAC evap drain hoses, but I've checked all these out, stuck rigid wire down them or poured a bottle of water to check it was draining.

Anyone had this issue? It's a 94 so it has the steel heater core lines from the firewall, but they weren't looking too bad when I changed the core, and some drips from the connection but they went away when I tightened the flange screw.

There's no overheating and the temp gauge stays steady.

[454cid]

I didn't hear much, but when this happens on a GMT-400 Chevy truck it's air in the lines. It means there is a leak someplace, but not necessarily the heater core. The air bubbles are getting circulated though the core and makes a gurgling sound.

[scot850]

The only other possibility is the drain line from the A/C unit. I can't recall if there is a drain line in the center of the floor behind the dash and running under the floor.

Other option is have you checked under the carpet is not wet? It could be the drains for the cowl where the wiper motor and fuse box are has blocked drains and they are leaking into the car when you are driving it?

Neil.

[BEJinFbk]

I didn't hear much, but when this happens on a GMT-400 Chevy truck it's air in the lines. It means there is a leak someplace, but not necessarily the heater core. The air bubbles are getting circulated though the core and makes a gurgling sound.

It does sound like air in the lines.
Could be the system wasn’t purged
of all air when the core was serviced.
Start with checking your coolant level.

[jsrnsis]

All the drains are clear, it's not when the car is moving like sloshing water, it's like its flowing through the heater core, like turbulent water. There's no bubbles in the coolant bottle thankfully. The carpet is wet on the passenger side but that's because the cabin filter housing wasn't sealing well in the cowl and letting water into the blower fan housing. It finally filled up and belched water out from under the dash when I turned the fan on.
Anyways, the radiator was replaced last year too, ill look at doing a coolant system purge, hopefully that's all it is, and check all the hose clamps.

It sounds like a rambling brook is flowing through my heater core.

[abscate]

These cars self bleed really well. I would guess the AC climate unit drain is plugged and full of water. You can pull the fan or power transistor pack to look into the climate unit for Lake Volvo

[454cid]

ill look at doing a coolant system purge, hopefully that's all it is, and check all the hose clamps.

It sounds like a rambling brook is flowing through my heater core.

I'd recommend using a cooling system pressure tester to look for leaks. Put it under pressure and then very carefully check everywhere with a flashlight. I think there is a uv dye that you could use, but you may not have to go that far to find it.

[jsrnsis]

I've never seen coolant on the ground, but there was a very very slight leak at where the hard pipes connect to the heater core that could have been pulling in air for a while, the leak went away when I gave that screw a good tightening.

I have accidentally opened the coolant reservoir when the engine was hot a few times since replacing the heater core. Recently I noticed the coolant was kind of low, filled it up to max, and then next time I was under the hood noticed the coolant tank was almost entirely full. No coolant at the water pump weep hole, which was replaced less than 20k miles ago.

I'm going to put it up on ramps and run it with the cap off and see if that burps anything out, and pick up a pressure tester if I feel like going out today.

[scot850]

I was going to suggest putting the car front up on axle stands and running the engine to see if it can help it burp an air pocket out.

Good Luck!

Neil.

[454cid]

I've never seen coolant on the ground...

Often times you won't on a hot engine. It evaporates before it gets that far. That's one of the reasons I recommend using a pressure tester.