Coolant issue?

[dperry4930]

Okay, brand new issue on my 2003 XC70 with 208k miles.
Losing radiator fluid, never see fluid on ground at our parking spot. I drive it today to see what is going on. Start out with cold engine and fluid halfway in resevoir. Drive about 5 miles, no issues, car up to temp, coolant still there. Drive to next errand, about 5 more miles. Get out, pop hood with car off, and expansion tank is full! Not sure what to do, come back and puddle of radiator fluid is in front of car. Start car, no fluid in expansion tank. Drive car home, get to parking spot and pop hood. Add fluid with car running to middle of range. Turn off car with hood up, look at expansion tank and fluid level is screaming up. Turn car back on, water stops going up.

One thing I noticed, the radiator fan was not running when I stopped and for some several minutes. However when I turned car off and the on (see above) the fan was now running and pushing air.

Finally, when I turned the car off the second time in my spot, the fan secured immediately.

What the heck is causing my fluid level to swing so widely? Why, since the fan definitely runs, does it turn off immediately upon securing the engine? Is that the root of the problem?

[ifnt420]

Looks like signs of air in the coolant system, causing the level to go up and down.
Could be as simple as a bad expansion tank cap, or worse case cracked cylinder wall.
I'd start with the cheaper replacement option, try to change to a new expansion tank cap.

[Astro14]

Sounds like air in the system. Fluid always expands immediately after shutdown as it heats up. I would try a fes more heat/cool cycles and a new cap.

[Scopeman]

Where is the puddle coming from? Radiator leaks are common. Pull the splash shield, run up on ramps and inspect. May need to dry off excess to locate leak. Attend to this, aluminum engines do not take well to overheating.

[Xheart]

If you have not completely serviced the mother of all systems for a while, it is time.
Use Volvo fluid.

[tmcmilli]

I agree that it sounds like pressure is building up in the coolant system. In fact that sounds almost IDENTICAL to my experience with what turned out to be a blown head gasket on my'97 850 with a 2.4L non turbo engine. I vote for a compromised head gasket causing pressure to build up in the coolant system as soon as the system warms up to operating temp.

In my case this buildup in pressure caused a fast rise in coolant level in the overflow tank as soon as the engine warmed up, to the point where it started forcing coolant out around the overflow cap. I was slow to figure it out but after some head scratching and a specific Google search for the problem of coolant level forcing its way out around the overflow cap (after replacing the overflow cap made no difference), I discovered the problem was more serious/expensive.

Just a hunch. I hope this isn't your problem. If it sounds like it might be, I would suggest don't continue trying to drive it like that until you're sure that this is not the problem.

[dperry4930]

Since it was after the engine was hot and the engine was turned off when I watched the fluid level rise dramatically, I wouldn't think it would be a head gasket, as that would happen more likely if the car was on. I appreciate the good insight, I am going to go cheap and replace the expansion tank and cap to begin with, and hope that it is simply air in the system. Once those are replaced, should I take the car somewhere and get a coolant flush (with the right fluid of course)? Would that ensure no air is in the system?

Anyways, I will keep you all posted as to the impact of the new cap and tank.

[Antherzoll]

Since it was after the engine was hot and the engine was turned off when I watched the fluid level rise dramatically, I wouldn't think it would be a head gasket, as that would happen more likely if the car was on. I appreciate the good insight, I am going to go cheap and replace the expansion tank and cap to begin with, and hope that it is simply air in the system. Once those are replaced, should I take the car somewhere and get a coolant flush (with the right fluid of course)? Would that ensure no air is in the system?

Anyways, I will keep you all posted as to the impact of the new cap and tank.

What helped my leaky reservoir cap was taking the rubber gasket out, flipping it 180* (or 540* if you like ), and installing it.

How I diagnosed a leaky cap was to listen to it when the engine was off and hot. Literally rested my ear on it. I replaced my radiator recently as it was having a leak once pressurized.

There are quite a few spots that can leak once the system has pressure. There are coolant lines leading to the turbo and for the PCV system so keep those in mind.