XC70 2010 radiator fluid was nearly empty;

[tholian]

I've been using the same car repair place for our 2010 XC70 since the car went out of warranty. On a recent trip we drove 250 miles and parked the car for 4 days while we hiked. On return the car immediately warned that coolant was low. I opened the reservoir and found it was empty of visible fluid. I put water in (a temporary fix), and we made it home. This car had a routine service in Feb, and was hardly driven since then. A day later, the fluid level remains as it was after I added water.

The car has 42k on it. These guys have worked on it twice, since the last time the dealer's service people saw it, in 2014 when it had 30k on it.

Another car we own had a recent 30k service (ie fairly major) and I found the windshield washer fluid was basically empty a few days after. It made me wonder if they had simply made a mistake, or if they were skipping things.

'Check fluid levels' is a routine part of any service for any repair place, I'd think. Alternatively, is it possible that the fluid somehow came out on it's own in a few months, without leaving any visible trace (the car is parted indoors). Alternatively #2, is it time for me to find a new place to service the car? <g>

[pbierre]

It's not uncommon for a 10-year old car to have a tiny pressure-leak in the cooling system. This will deplete the coolant volume over weeks or months.

Finding the leak is a matter of looking for the telltale residue (greenish white) caked outside where the vapor has leaked. The most common leak point is the reservoir, a loose or defective fill cap, or hose bibs. But, it could also be at the clamped end of a hose (the factory "crimp" clamp having gone lazy).

Less frequently, it's an internal coolant leak (gasket failure), in which case there's no residue since the coolant goes out the tailpipe as steam. That would be unlikely on a car at 42K miles.

Some alternate ways to find a steam leak are visually by probing with a mirror for condensation, or with the engine off in a quiet location, listening for a soft, high-pitched whistle.

Your radiator coolant level was sensed as being "low", but this is triggered while there is still plenty of coolant in the system. An empty reservoir merely indicates you've begun losing coolant. Any repair shop would have seen this and looked for the leak, so I would assume the leak developed post-service.

The windshield washer tank?....most of the volume is down low where it can't be seen from the fill port. When you remove the fill cap, don't expect to see any fluid.

[tholian]

The windshield washer system was actually empty or very close to it. I happened to check it before we took a long drive (this is the non-volvo) a day or two after it had been serviced and it took a -lot- of water. They may have missed it due to human error, but for sure it was empty after they gave the car back to me.

Thank you for the rundown on the radiator system, very thorough. The reason I think they didn't check it is that the car was parked in a cool indoors location since it's Feb service, probably had 50 miles on it at the most until last week when we drove it 250 miles. After leaving the car for 4-5 days, again cool shady spot, the warning arose and the reservoir tank was empty. After refilling and driving 250 miles back home, the coolant level is exactly the same. I can't see how the second 250 miles would have zero impact on the coolant level, and the first made it lose enough to fire off the warning. Unless you think it's reasonable that basically parking it indoors in a cool environment could whither the just serviced coolant level to the point of the warning?

Am I right in recalling that the warning said something like don't drive the car until coolant level is restored (in effect)? Or does it actually prevent one from starting the car? I should have taken a picture of the warning.

[pbierre]

The windshield washer system was actually empty or very close to it. I happened to check it before we took a long drive (this is the non-volvo) a day or two after it had been serviced and it took a -lot- of water. They may have missed it due to human error, but for sure it was empty after they gave the car back to me.

Thank you for the rundown on the radiator system, very thorough. The reason I think they didn't check it is that the car was parked in a cool indoors location since it's Feb service, probably had 50 miles on it at the most until last week when we drove it 250 miles. After leaving the car for 4-5 days, again cool shady spot, the warning arose and the reservoir tank was empty. After refilling and driving 250 miles back home, the coolant level is exactly the same. I can't see how the second 250 miles would have zero impact on the coolant level, and the first made it lose enough to fire off the warning. Unless you think it's reasonable that basically parking it indoors in a cool environment could whither the just serviced coolant level to the point of the warning?

Am I right in recalling that the warning said something like don't drive the car until coolant level is restored (in effect)? Or does it actually prevent one from starting the car? I should have taken a picture of the warning.

I have the same car, same year, but I haven't encountered that warning. Volvo doesn't publish much about the software. First thing I'd do with the radiator coolant is maybe use a piece of tape to mark the cold-liquid-level...check it again after 100 miles. Get a sense of how fast or slow it's losing coolant.

[Rabid Koala]

With my previous XC70, I just got in the habit of checking the coolant level at every fill up when I check the oil. I have found minor leaks like a loose hose clamp that way.

[pbierre]

It's not a good idea to open the cooling system reservoir cap when the engine is hot. The coolant system is under pressure. When you release the pressure, there is an instant cooling "shock" throughout the cooling surfaces (engine bore channels). Metals do not like such instant cooling....they are designed for gradual heating and cooling.

I've heard of engine blocks cracking in response to de-pressurizing the cooling system at full engine heat. It happens almost instantly.