Coolant Gurgling sound from Coolant tank?

I had my 06 Boxster out for the first run after winter, after a 15 minute drive up the hwy I pulled over to check over car for leaks ect.I popes open the rear boot (car running) and noticed a Gurgling noise like a kettle boiling or water running coming from the coolant tank.Ther were no leaks around the coolant cap or from the coolant overflow line at the right rear wheel and coolant level was within the normal range.Ive had the car for 8 years and never noticed that before.Is this a normal .It almost sounds like air bubbling with the water flow.I may have had my air conditioner on also not sure if that matters. Im wondering if theres air in the system. Will the coolant bleed properly if I lift the bleeder clip while driving or is this something that needs to be done with a cold motor ie: run in park at 2500 rpm with heater on high and clip in vertical position. Thx for any advise.

It's possible your overflow tank cap or fill cap are not holding pressure. If they're leaking the coolant can start to boil. Check around both caps for telltale white coolant residue. The overflow cap is designed to vent pressure at a certain point, the fill cap is just a seal. Neither one lasts forever, and if they're original to your car it might just be worth replacing both: they're not very expensive and it's super easy to do.

Gubi, my fill cap is new approx 10000 k ago andnkt showing any signs of leaking or white powder.I had that before and the new cap (updated) solved it. Were is the overflow tank cap located. Under the carpet on the tank? This is an 06 Boxster and only has one fill point or cap in the system unlike the caymans .

Ah, sorry, didn't realize you just had the one cap . It's possible the cap could've failed again, I suppose. Or there could be a leak anywhere in the system if the issue is it's not holding pressure.

Remove the engine top cover to access the coolant tank. Sent from my XT1650 using Tapatalk

I pulled all the engine covers and inspected the coolant lines, water pump ,Lines under car and at front going to rads. I also pulled the carpet around the coolant tank and there are no leaks to be found at least that I can see also no leaks from coolant cap and no white residue around cap . So I flipped the bleeder on top of the tank and di the cold start up bleed procedure. When I was done and car cooled down (back to cold) the coolant had dropped from approx 3/4 full to just above Min.So maybe 1 inch drop. Dont here the bubbling as much now so maybe a pocket of air in system ,either that or coolant is going somewhere it shouldn't . Do these cars have a tendency to lose a lil coolent over a year even if no leaks spotted.I read that a lil seepage they the weep hole on the pump is normal a the coolant is also used as lubricant as well as cooling.Going to monitor it over next few weeks and see if it stabilizes. Thx for help all.

When I did my thermostat and water pump recently I noticed that mine would gurgle after shutting the engine down before the bleeding process was complete. Not sure if that helps, but it could be a sign of an air pocket moving through the system after water pressure subsides.

FlyinAg,Thx for reply. I also checked my pump ,pulled belt and no play, no weepage or seepage.None. I had changed the pump myself maybe 30k ago. Still like new. Im still running the original Stat now with 145000 Kilometres on motor so I picked up a new one to install soon, just incase. After adding approx 1.5 cups of coolant and bleeding twice the level seems to have stopped dropping.Stays at 1/2 way now cold and rises up to 3/4 when hot. Very Strange! Hope its not going in motor ,no signs on oil filler cap of any creme colour to oil. Wonder were the coolant went.Maybe ive been driving around for the last 2 years with an air pocket,who knows Lol

I personally think that if you fill a car to the max line and then use it for awhile it gets hot enough to dump the extra coolant it doesn't want and then when you check it it's down close to min. I use to top it and then saw it kept going down to the level it want so I don't add any unless it's really low and then would suspect a problem.

Augie, Yes the level has now gone from approx 3/4 full COLD to 1/4 full COLD. How low can u go before being a possible problem. Below Min?

I can smell coolant from rear right side after driving but see no coolant leak on floor, does it vent smell of coolant from the overflow drain? Level has never gone over full HOT.

Usually if it goes below min there's a problem. There's no coolant in right or any rear. Have you removed the engine cover to look better. These cars have problems with coolant tank needing to be replaced . An 06 is 14 yeas old. I would guess it's the tank. You would need to pull back all the carpeting and sound deadening in the trunk you see everything well. Probably would be soaked.

Yes did that looked dry ,maybe its a slow leak and drys before dripping.I will wait and see if it goes below Min Thx

ok hope it will stay where it belongs If under engine cover and carpet is dry and still using coolant and smelling it maybe internal engine problem like a gasket leaking into combustion and being burnt up.

Oh crap,i pray its not but possible I guess,Fingers crossed. I guess if oil has a white milk shake look or coolant has brown look (not pink) r signs of that. I had plugs all out week ago and they all looked good, one was a lil more oily than the other 5 (on threes only) but it also had a cracked coil so maybe not getting a complete burn so I replace the one coil.Other coils looked ok visually.

Hope so for your pocketbook

Just make sure you don't see any crusty dried coolant stuff near any of the coolant hoses, water pump, thermostat, etc. Make sure you check the front of the car up by the radiators if you haven't as well. You might not find the wet leak, but the signs of one that is dry. When you bleed out a car's coolant system, I have seen the level in the reservoir rise and fall as the system heats up, and when the thermostat opens. I had a heck of a time bleeding a partially filled system after changing my pump and t-stat. Fluid would drop after starting as if air was being burped out, then as soon as the fans would come on around the time the t-stat opened, the fluid level would rapidly rise. I am guessing there was a huge air pocket that was being pushed back in the system, but couldn't escape whatever nook or cranny it was stuck in. If I were you, I would get it up off the ground, pull all of the under body panels, and really give it a look for signs of a leak from front to back. I would change the oil and look for contamination. Should be obvious if present. If you are empty handed, then maybe drain the system, get a vacuum refill system, check for leaks, then refill. Note: I spilled freakin coolant all over the place in the engine. I even washed it off best I could. I still catch a whiff of that stuff every now and then. Just because you think you smell it might not mean it is actively leaking. But do check!