2008 XC90 Coolant problem


New member
Castle Rock
United States
What I Drive
2008 Volvo XC90
Hi, All,
Perhaps someone can give me some insight as to what is going on with cooling system.
Background: I recently had the vehicle in the shop because of some massive coolant leaks. After three visits, the problem was finally cleared up, but not after having two hoses, the plastic reservoir, and the thermostat replaced. Nearly $700 total sunk into the repairs.

Now, there is something else going on which I am scratching my head over.
A cannot drive more than two miles without the red warning light and 'Low Coolant' message coming up. Temperature guage remains normal. The first time this happened, I topped the reservoir with coolant to the recommended level. The next time I drove the vehicle, I noticed steam coming from under the hood, and the temp guage was going high! I stopped and found that coolant was boiling in the reservoir tank.
After allowing the motor to cool down, I limped the vehicle home.
When things had cooled completely down, I checked and the reservoir was completely empty. Befuddled as to where all that coolant went. No indication of system leaks anywhere.
Since then, I can only take the vehicle on short hops around town before this 'Low Coolant' and boiling stuff starts happening all over again. I've topped off the coolant several times in the interim with no change. Obviously, there is something seriously amiss.
Any thoughts?