2006 s40 leaking coolant

[Mrichards]

I've had an issue with my coolant leaking since about December. Suddenly I had to top my coolant off every week or every few days. Couldn't find any sign it actually leaking out of my car, so I took it to a mechanic to inspect the whole cooling system. He didn't find any issues or leaks, just a hose on my radiator needed tightened. That didn't solve the issue.
I was worried for a while that it was a problem with my head gasket, but I've driven at least 3k miles with this issue- I haven't noticed any change in how my engine performs, no weird exhaust, and the oil looks fine. No kind of smell of coolant inside the car either.
*Here's the thing, the coolant doesn't seem to drop below a certain level, as shown in the attached picture. I've never gotten a low coolant or temperature warning. I really have no idea what it could be, or how to handle it.

[gamequeazy]

My first guess would be a crack in the coolant reservoir, especially if its original. You can pull it out fairly easily and check, but they are known for cracking, my guess is there is a crack just above where the level... levels out at.

The other usual suspect is the upper rad hose, (the octopus) that routes from the drivers side of the rad over the trans to the thermostat housing, but that probably would just leak and leak, not sort of stop at a certain point.

Changing the coolant reservoir is pretty trivial, changing the octopus hose requires a bit more digging to get the airbox out of the way and draining off the coolant.


Also, fun note: there is no coolant level sensor in the P1 volvo's so don't rely on that to warn you of low coolant levels.

[MoVolvos]

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Borrow the tester from the any of the big national parts stores. The Test Liquid is not expensive. Could well be a slow head gasket leak if you aren't seeing it anywhere under the hood.

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[Mrichards]

I didn't see any cracks in the reservoir but im wondering if i just didn’t look carefully enough. Did the liquid test, and it turned out fine. Still confused as to what it is, but I'm going to replace the reservoir and see if that resolves the issue.