Heater Core Gurgle

[vamos]

I know this is a well worn theme but I'm having no luck shifting the air out of the heater core in my 96 Legacy EJ22.

 

Tried up on ramps, running the motor till the fans come on and thermostat opens, spill free funnel used. Reverse flushed the heater core plus coolant flush. Have pressure tested the system, all ok. Heater has great heat, not losing coolant. Still can't move the air.

 

Here's what I'm thinking. Car up on ramps again. If a pressure tester is attached to the radiator neck and with the bleed plug off and the overflow hose crimped, would pressure once applied get to the heater core and displace the air or will the pressure be stopped by the closed thermostat (doing this on a cold engine)?

 

Got to be a surefire way to move this annoying air and stop the very audible water noise. It's there all the time when driving.

[heartless]

car up on ramps

running the motor till the fans come on and thermostat opens,

spill free funnel used

 

Heat turned on full hot??

 

if the heat is not set to full hot, then no, you wont get the air bubbles out of the heater core - Must set the heat to full hot setting so that the coolant can flow thru the heater core. it isnt necessary to run the fan, but the temp setting must be all the way to hot.

 

repeat the above procedure with heat setting on hot, and run for several minutes after reaching operating temperature.

 

trying to pressurize a cold system probably wont work because of the closed thermostat...and could in fact cause more problems than it solves...

[johnceggleston]

if the heat is not set to full hot, then no, you wont get the air bubbles out of the heater core - Must set the heat to full hot setting so that the coolant can flow thru the heater core. it isnt necessary to run the fan, but the temp setting must be all the way to hot.

 

i don't believe this is accurate, at least not for 90s subarus. they do not control the flow of water thru the heater core, only the flow of air across the heated core. the flow of coolant to the core even by-passes the t-stat.

 

i have even herad of some engines over heating when the heater core is clogged. and then a back flush of the core fixing the problem, i think.

[danbennett2u]

Not sure if it matters but does your thermostat have one of those little holes with a loose metal stopper in it? I believe that is an air valve that allows air to bleed out of the system when the thermostat is closed, the last thermostat I replaced did not have one but the replacement did.

 

Just a shot in the dark on that though.

[vamos]

Heat turned on full hot??

 

if the heat is not set to full hot, then no, you wont get the air bubbles out of the heater core - Must set the heat to full hot setting so that the coolant can flow thru the heater core. it isnt necessary to run the fan, but the temp setting must be all the way to hot.

 

repeat the above procedure with heat setting on hot, and run for several minutes after reaching operating temperature.

 

trying to pressurize a cold system probably wont work because of the closed thermostat...and could in fact cause more problems than it solves...

 

Hi thanks for the reply. Yes, the heater is set to hot. I have watched a few You Tube videos on this and read up a bit on this so feel I am doing everything right. Perhaps pressurizing a hot system after the thermostat opens may work.

[vamos]

i have even herad of some engines over heating when the heater core is clogged. and then a back flush of the core fixing the problem, i think.

 

Thanks for the input. I have back flushed the core. No gunk and good flow both ways. Engine temperature is not a problem ... needle always just below half way point.

[nipper]

Did you ever do it the proper way yet?

 

drain radiator with cap off cold (just to have a starting point)

 

Start car

SLOWLY refill radiator

When filled wait for t-stat to open. There will be a surge of fluid then everything settles down.

Keep filling system.

Replace cap, top off overflow.

Drive around block.

 

Allow to cool, repeat once if needed (not the draining the rad part).

 

More then once then air is getting in someplace.

 

This subaru doesnt have a heater valve so skipping it open to hot isnt a huge error.

[vamos]

Did you ever do it the proper way yet?

 

drain radiator with cap off cold (just to have a starting point)

 

Start car

SLOWLY refill radiator

When filled wait for t-stat to open. There will be a surge of fluid then everything settles down.

Keep filling system.

Replace cap, top off overflow.

Drive around block.

 

Allow to cool, repeat once if needed (not the draining the rad part).

 

More then once then air is getting in someplace.

 

This subaru doesnt have a heater valve so skipping it open to hot isnt a huge error.

 

Thanks. Haven't tried this. Will give it a shot later and post my result. I'll do it with the front of the car on ramps unless you think I don't need to.

[nipper]

No ramps, ramps bad, bad ramps.

[vamos]

Did you ever do it the proper way yet?

 

drain radiator with cap off cold (just to have a starting point)

 

Start car

SLOWLY refill radiator

When filled wait for t-stat to open. There will be a surge of fluid then everything settles down.

Keep filling system.

Replace cap, top off overflow.

Drive around block.

 

OK, had a go at doing it the proper way. here's what happened.....

 

Drained radiator with cap off .... check

Started car.....check

Very slowly filled radiator .... check

Waited for t-stat to open ....Did not happen

 

What did happen is my fans came on and stayed on. The t-stat didn't open and the temperature started to go beyond the normal range so put the radiator cap on and went for a very short drive hoping this would open the t-stat. Temperature gauge went to the very top and no heat from the heater. Got back (only travelled a half mile). The water in the radiator was boiling and I started to hope I have'nt done any permanent head gasket damage.

 

The other times I tried to bleed the air by putting the nose up on ramps, spill funnel, holding the revs up, etc The t-stat did open but never shifted any air from the heater core. This time by draining the radiator, the t-stat didn't open and gave me a scare when the temp gauge went ballistic and only cold air from the heater.

 

So I left the car for 8-9 hours to get cold. Checked the coolant level and took the car for a drive. A short drive at first and when the temp gauge stayed at normal and the heater was blowing hot air I went for a longer drive (30 miles) really giving it a bit of a push. All was OK.. temp gauge just under half way, blowing good heat but the gurgling water from under the dash was still there. If anything sounded louder than before.

 

After the drive, I checked the radiator cap and it was cool to the touch, the bottom radiator hose was cold although both top and bottom hoses felt like there was good pressure in them.

 

I've had enough of a scare to give up on this for the time being. It's only noise and as the car is running OK who am i to keep poking at it. Since I have only had the car a month, I will soon be taking it to a Suby mechanic to have the timing belt changed along with the other bits and pieces and I will leave it to him to clear the air from the core.

 

Interestingly, I met another Suby owner at the gas station and his Outback had the same gurgling noise. Perhaps it's just a quirk that some Subys' get an unmoveable air-lock in the heater core.

 

Thanks everyone for your help. Beaten by a car, for what should be a simple fix. But what really irks me was my wife's last word on my attempt to fix this when she said "Just let the mechanic do it"... My manly gonads aren't swinging as they should be.. somehow I must redeem myself.

[1997reduxe]

Well, I hate to chime in with the wife, but...

 

REally, you didn't mention why you were doing the cooling refill to begin with? Had you worked on the cooling system? Replaced thermostat?

[johnceggleston]

i saw no mention of the vent bleeder plug. did you remove it during the filling process? this is important.

 

 

legacys and outbacks have a bleeder vent plug on the top of the rad at the top hose.

it is supposed to be open when filling the cooling system.

it is almost impossible to fill it correctly with it closed.

 

it has a phillips head fitting. at 26.25 inches in pic.

i'm not sure imprezas and foresters have them, but i don't know.

 

[mikaleda]

i had this problem just a couple days ago. you have to fill the radiator with the car NOT running it will take close to an hour for it to fill completly just keep adding coolant as it goes down take a look at my thread of problem (weird overheating problem) if you read the whole thing it will tell you how to fill the system with out air bubbles. you'r overheating problem was caused by an air bubble it shouldn't have affected you'r head gasket.

[Fairtax4me]

Because of the placement of the thermostat on these, coolant from the radiator doesn't actually go into the engine when it's poured in. The radiator fills but the engine is still empty. Remove the upper radiator hose and fill the engine with coolant first, quickly replace the hose then fill the radiator with the bleeder screw open. Close bleeder, Start the engine, top off as necessary while running once the thermostat opens. Cap radiator turn off engine and allow to cool.

Heater on or off has no effect on these systems because coolant is constantly flowing through the core.

[nipper]

Proper subaru T stat has a jiggle valve to help filling.

 

Everyone who does it the proper way of old never has an issue with air bubbles.

 

No need to fill it cold as that is painfully slow. The thermostat is on the bottom. Fill the radiator with or without the air vent open slowly and it is the same thing as pouring it down the neck.

[vamos]

Well, I hate to chime in with the wife, but...

 

REally, you didn't mention why you were doing the cooling refill to begin with? Had you worked on the cooling system? Replaced thermostat?

 

Cooling refill was done in an attempt to bleed the trapped air in the heater core. This is the first car I've had where I've heard this and after reading up on how other s have tackled it I thought it was a fairly simple fix.

[vamos]

i saw no mention of the vent bleeder plug. did you remove it during the filling process? this is important.

 

Thanks John.

 

No, I didn't because an earlier post did not mention this when they stated "THE RIGHT WAY" method!! I have however on previous attempts taken the bleed plug out and filled the radiator through it. Also, with using a spill free funnel. I have let the car run up to an hour venting out as much air as a could.

[vamos]

i had this problem just a couple days ago. you have to fill the radiator with the car NOT running it will take close to an hour for it to fill completly just keep adding coolant as it goes down take a look at my thread of problem (weird overheating problem) if you read the whole thing it will tell you how to fill the system with out air bubbles. you'r overheating problem was caused by an air bubble it shouldn't have affected you'r head gasket.

 

PHEW! Good news about the head gasket. Hmmm ... maybe I'll give this another shot when the wife's gone to visit her mother.

[vamos]

PHEW! Good news about the head gasket. Hmmm ... maybe I'll give this another shot when the wife's gone to visit her mother.

 

OK, so here's an update. A few days ago, I take the car in to have the timing belt done, plugs, leads and fuel filter. So that gets done and on picking up the car I make a casual remark about the water gurgle about how I have been having a hell of a time trying to burp the air out of the heater core.

 

He says "oh yeah, I did hear that when I took it for a drive, you know what you should do ... swap the two hoses around where they connect to the engine and then have another go at burping it again."

 

I thought can't hurt to try, so next day when the ball and chain goes to visit her sister, I'm out there like a flash spill free funnel and screwdriver in hand. Unscrew the clamps on both hoses and swap them over. Was quick to do and I didn't lose much coolant. Spill free funnel on, coolant in, start car and wait for t.stat to open. All went well and the result ....GURGLE GONE. I'm beating my chest and swinging through the trees again. Happy Ending.

 

P.S. The mechanic mentioned that he tried this method on other cars and it worked so it isn't a subaru specific fix. Hope this helps others.

[mikaleda]

cool good thing to know.

thanks for sharing.

[vasy]

OK, so here's an update. A few days ago, I take the car in to have the timing belt done, plugs, leads and fuel filter. So that gets done and on picking up the car I make a casual remark about the water gurgle about how I have been having a hell of a time trying to burp the air out of the heater core.

 

He says "oh yeah, I did hear that when I took it for a drive, you know what you should do ... swap the two hoses around where they connect to the engine and then have another go at burping it again."

 

I thought can't hurt to try, so next day when the ball and chain goes to visit her sister, I'm out there like a flash spill free funnel and screwdriver in hand. Unscrew the clamps on both hoses and swap them over. Was quick to do and I didn't lose much coolant. Spill free funnel on, coolant in, start car and wait for t.stat to open. All went well and the result ....GURGLE GONE. I'm beating my chest and swinging through the trees again. Happy Ending.

 

P.S. The mechanic mentioned that he tried this method on other cars and it worked so it isn't a subaru specific fix. Hope this helps others.

 

Did you swap the hoses back after burping, I guess not? I wonder what is the theory behind this swap. I'm assuming your heater hoses were properly connected to the heater core before the swap.

[vamos]

Did you swap the hoses back after burping, I guess not? I wonder what is the theory behind this swap. I'm assuming your heater hoses were properly connected to the heater core before the swap.

 

No, haven't put the hoses back and they were properly connected before the swap. Temp gauge is fine and blowing great heat. Not sure about the theory but reversing the flow into the core certainly fixed the problem for me. Thanks for asking.

[bluedotsnow]

I noticed a gurgle on start for a long time after servicing my 96 lego several times for various coolant reasons.... but I wrote it off drove around and after a few oil changes had passed it seems to have gone away. have you tried driving the car a long distance? how about using a vacuum device to suck coolant into the engine, last time my coolant was changed we used such a device. not sure if this helped but as long as your air pocket is not causing overheating just drive it.

[vamos]

I noticed a gurgle on start for a long time after servicing my 96 lego several times for various coolant reasons.... but I wrote it off drove around and after a few oil changes had passed it seems to have gone away. have you tried driving the car a long distance? how about using a vacuum device to suck coolant into the engine, last time my coolant was changed we used such a device. not sure if this helped but as long as your air pocket is not causing overheating just drive it.

 

Thanks for joining in with your suggestions but I no longer have an air pocket in the heater core or anywhere else .. the gurgle is gone (read my update a few posts back).

I did actually read of the vacuum method to suck the coolant into the block, also had what I thought was a good idea of taking the radiator bleed plug out then attaching a pressure tester to the radiator fill point and forcing the air out along with a lot of coolant but never got around to this.

I actually gave up and was learning to live with the sound until my mechanic told me to just reverse the heater hoses where they go into the block. Did this and it worked.

[pearlm30]

I had the same problem ever since my 98 forester EJ22 swap. Not sure if I hooked the heater hoses wrong or what during the swap. But I decided to reverse them this morning. Wow, no more water gurgle sound when driving and I have better stronger heat at idle. Hope this may help someone. Thanks to OP

 

OK, so here's an update. A few days ago, I take the car in to have the timing belt done, plugs, leads and fuel filter. So that gets done and on picking up the car I make a casual remark about the water gurgle about how I have been having a hell of a time trying to burp the air out of the heater core.

He says "oh yeah, I did hear that when I took it for a drive, you know what you should do ... swap the two hoses around where they connect to the engine and then have another go at burping it again."

I thought can't hurt to try, so next day when the ball and chain goes to visit her sister, I'm out there like a flash spill free funnel and screwdriver in hand. Unscrew the clamps on both hoses and swap them over. Was quick to do and I didn't lose much coolant. Spill free funnel on, coolant in, start car and wait for t.stat to open. All went well and the result ....GURGLE GONE. I'm beating my chest and swinging through the trees again. Happy Ending.

P.S. The mechanic mentioned that he tried this method on other cars and it worked so it isn't a subaru specific fix. Hope this helps others.

Edited December 31, 2016 by pearlm30