I'm hoping someone may be able to help me figure out the cause of the coolant loss I've been experiencing the last several weeks. My 98 V70 XC has 146,000 miles, and is otherwise in flawless condition.
The problem started with a small, visible leak from the coolant hose at the rear of the engine which caused a small puddle of coolant on top of the rear heat shield. This was easily fixed by my independent shop by tightening the hose clamp. They pressure tested the system and all was ok, but within a couple of days, I was hearing a gurgling sound from the dash (I assume heater core) on startup, and level was low in the overflow tank. I've had it in 3 times now to my independent shop, and once to the dealer, and they have replaced the thermostat and the overflow tank cap, and they tell me the pressure tests are all OK. There is never visible coolant on the ground, but I find myself having to add about a quart every 75 miles or so. The engine has never overheated. Once I did see coolant down the side of the engine compartment near the overflow tank, so I'm wondering if the overflow tank is somehow leaking. The dealer suggests replacing the head gasket (~$1500), though the block test was supposedly OK.

Any suggestions would be GREATLY appreciated!
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86 240 DL 130K; 98 V70 XC 132K(Bilsteins, ipd strut tower brace & sway bars, Wetterauer chip)