Hi Guys,
I am new to this forum, so please be gentle.

So, I purchased a great looking 2013 Volvo V40 T3 Elite 1.6L 115K KM from a car lot the other day. On the way home I got the low coolant level warning. I topped off the coolant and went on my way. Well, now it is just drinking coolant.

I can top off the overflow and within 15 miles of driving, the light is back on and the coolant level is a cm below the min. mark.

I have checked floorboards: Dry

I do not have much white smoke from exaust...just a little steam that dissipates before hitting the bumper while in traffic, but only happens now and then

There is no smell of burning coolant anywhere

The engine is running great and no loss in power at all. I am getting the expected amount of fuel mileage.

The oil looks like oil. Not milky or foamy..normal color and smell and at the correct level. Same with transmission fluid.

Temperature Gauge is always where it should be, Dead center.

No puddles, pools, or wet anywhere near car when parked and no leaks visible under the hood engine running or not.

One strange thing: The cooling system appears to be under a lot of pressure. Even after letting the car cool, when I release the overflow cap there is a big release of compressed air. I can let the car sit overnight and there is a ton of pressure under the cap in the morning before I start the car. Also the radiator hose is very hard when the car is running or not. Sometimes, when I remove the cap from a (seemingly) empty overflow tank, fluid will suddenly rush into the tank and fill it (has overfilled it as well) even with the engine off.

Back to the pressure in the reservoir. The coolant looks a bit dirty to me (only 3 days old) and does smell a bit like exhaust. Now, when I remove the cap, the fluid rushed back into the reservoir and returns to normal levels. If I tighten the cap and let the engine run, the coolant slowly depletes from the reservoir until it is empty and is replaced by high pressure gas/air/fumes. The longer I run the engine the more air gets released when I take off the cap.

My question is this: Can I have a blown head gasket that is letting exhaust fumes into the coolant under pressure? So, as the exhaust pressure builds, it moves to the highest point and pushed coolant out of its way rather than actually expelling it? So, when I release the pressure the fluid just moves back into normal position? Are there any other problems that could cause these symptoms? If it was the head gasket, is it possible that the one and only symptom would be dirty coolant under pressure with extra air/fumes in the cooling system...with seemingly no coolant going into the cylinders? Also, if this was the case, would the cooling system still pass the pressure test? That is the part that is really stumping me...it passed the pressure test.
Thoughts?

Thanks!

 

Moved thread from the forum issues board (for issues with the forums not cars) into the S40 board (more viewers than V40s).

As to your question on head gasket symptoms - yes a failed head gasket can allow combustion gasses to add pressure to the coolant system. There are test kits to sample the coolant for HCs - should run about $30-40 for the kit.

You can put a pressure gauge on the system to see what its running. The coolant system will have positive pressure at temperature (to raise the boiling point of the coolant) so your pressure test is to make sure there's no leaking Typically this is done at a moderate pressure ie 16 to 18 PSI. Depending on the color of your overflow reservoir cap you can get a sense of the pressure rating but the system should be in the 18 PSI range with the green caps rated at 22 PSI. Only time I've ever had a cap blow out was when the thermostat failed on my 850 - temp gauge rose quickly and popped the cap (no damage).

 

Update on my symptoms today.

My car is blowing what seems like white smoke from the exhaust. Much more than just morning temperature mist. Is it for sure that my coolant is being burned somewhere causes white smoke while idle?

 

If that is what is happening, that's very serious. Coolant is leaking in the engine *maybe*. And if it's the head gasket, it needs to be replaced ASAP. Go to a shop somewhere and have them check, it's literally a 5 minute test and you will know for sure.

https://gobdp.com/blog/can-drive-leaking-head-gasket/

 

The repair guys said, my thermostat is bad, and not working as expected, causing the coolant not to flow as it should hence coolant being thrown out in overflow tank. Not sure if its true though, because my car still made white smoke from time to time

 

the white smoke could simply be condensation. Now that the cooling system is sorted out, you can track the level of the coolant. If the car is consuming coolant then the diagnostic process begins. In the mean time, do an oil change and then after a drive and cool down, check for any froth under the oil fill cap or on the dipstick. Also, if you are sucking coolant into the cylinders, the exhaust may take on a sweet smell.

 

Oil is fine, no coolant mixture. I figured that the 'White smoke' is just condensation as mt6127 said.
Although the volvo specialist replaced my Thermostat, still coolant is being lost somewhere.
This is very frustrating. I can fill it up now, drive around for a few km's, come back, uncap the reservoir after its cooled down, and the coolant level will come up just below the level i filled it up to.
What are the symptoms i need to look out for if somehow, coolant is deposited into my cylinders?.

 

[QUOTE=Slibo;473415]Hi Guys,
I am new to this forum, so please be gentle.

So, I purchased a great looking 2013 Volvo V40 T3 Elite 1.6L 115K KM from a car lot the other day. On the way home I got the low coolant level warning. I topped off the coolant and went on my way. Well, now it is just drinking coolant.
(snip)

Our 1972 Volvo 145S has been having mysterious coolant disappearance. I just discovered the issue.
One of the hoses connecting the heater core to the engine - hidden behind the engine against the firewall - has developed a drippy leak. The leak is not near the somewhat cracked ends, which I had noticed and checked to be dry, but underneath in the middle. The hose is near the top of the engine, so it only dripped when the engine is turned off IF the system was *completely full* of coolant. (Having looked below for leaks many times, I was astonished to see dripping from the bell housing underneath after filling both the radiator, and the overflow tank to the MAX mark. I had just replaced the thermostat.) Running, especially vigorously, it lost coolant as the liquid circulated through the heater hose. The overflow tank often had some content even though the radiator itself was down - inspection required removing the "do not open" cap on the radiator itself. I just ordered hose #680872 from vp-autoparts.com (a wonderful source) and I expect that to solve the problem.
See 140 old type (-1972) parts catalog page 5-A09 at volvotips.com (bless their reference materials).

 

If the thermostat fails your temperature guage will flactuate , if it fails in open then it will run cold and if in closed then it will overheat , as you guage (if working) does not I dont know where the reason was to replace it , did he show you the old one , if you have it just place in a glass cup and pour hot water on (boiling ) and it should open and cold water it should close.
Tracing a small leak is impossible without doing a pressure test of the cooling system , when a head gasket fails it does not always blow into the motor , it can blow out as well
If you thing the pressure is too much then the coolant pressure cap is probably faulty , but get a coolant pressure test done

 

mine is exactly the same thing... please read and tell me if all of this fits yours too.
i have a 2004 volvo v70. it runs pretty good. with the engine warming to 1/2 after 10 min of driving. But it often blows cold air from heat vents.. and it is consuming coolant, yet no visible leaks to ground. No coolant smell inside from heater core. The car blows white smoke out the tail pipe, and sometimes out the top of the engine[near the vvt oil solenoid]. I think i even saw coolant coming out there on top of engine There are a decent ammount of bubble going back into the reservoir , but a combustion leak test showed no combustion gasses in the coolant, ie, no color change-- liquid stayed blue for 5 minutes. Plus the spark plugs are oily[not milky, not clean, not white], and the oil is clean. Lastly, The car never overheats... even if the coolant gets low. oh, and the pressure test was fine... held 15psi for minutes.
PLEASE TELL ME IF YOU SEE ANY COOLANT LEAK OR SMOKE FROM TOP OF ENGINE NEAR RESERVOIR :] that may help us figure this out

 

OP was from like 3 years ago. Best to read through this and other threads to come up with a plan to figure out where the coolant is going. There's really no that many places - hoses, reservoir, radiator, heater core to start. A properly equipped shop can do a pressure test - ie apply pressure to the system to see where an external leak may develop and I'm not sure if "holding 15 PSI" is the right answer. Volvo's run a sealed system so the system pressure will go over ambient pressure to something like 1.2 or 1.3 bar ~ 17 PSI or so in normal operation plus you may have a small enough leak to loose coolant but not drop the pressure significantly. As I noted, there's plenty of posts for diagnosing mystery coolant losses. Head gasket is your worst case scenario. More likely you have a failed hose, a cracked seal in the radiator or a crack in the reservoir.