Hi all, first time poster.


I own a 2002 XC70 with 143K miles. About a month ago, I got a "Coolant Low, Stop Safely" warning while driving home from work. I got home and let it cool off, then checked the coolant tank. I was right at the min fill line. I let my Volvo guy look at it and he could not locate any leaks.


Since then, I have been losing coolant more and more quickly. I took it back to the shop last week because my coolant had drained from the max fill line to the min fill line from the time I left for work to the time I got home. They said my coolant tank cap was cracked, which was probably causing coolant to boil out of the tank and evaporate. I got a new cap, but it hasn't helped.


Last night I filled the tank to the max fill line. When I got up this morning, it was back down to the min fill line. It had been sitting overnight. I cranked it and the coolant warning light immediately came on.


I need help tracking down the problem, because my Volvo shop seems to be stumped. When I take the coolant tank cap off in the morning after the car has been sitting overnight, the tank hisses, so it seems to be holding pressure. I still can't locate any leaks. I haven't had any performance issues. The engine temp gauge is reading completely normal. I haven't seen any smoke or steam out of the hood or exhaust. The only thing I have noticed is a hissing noise that appears to be coming from the tank (I noticed this this morning). I know this model has transmission problems, sometimes caused by coolant leaking into the transmission. The previous (and 1st) owner replaced the trans at around 65k miles as a precaution, and I figured I would have some significant performance issues if this much coolant is leaking into the trans. I haven't checked the trans fluid yet.


Any ideas on where to start looking?

 

Usually it's the heater. You'd think all that coolant working its way under the carpet would be obvious, but believe me it's not. The carpet is pretty impervious and the smell of it doesn't get through until you take the carpet up. The heater is very easy to fix.


if the transmission fluid has water in it, it'll look like chocolate milk (green and red makes brown).

 

thanks for the reply.


I don't see any signs of a leak under the carpet.


The car started running rough when I started it in the mornings, for about 30 to 60 seconds. This got more frequent over the past week or so, to the point where it would start to run rough while I was sitting at a stop light. No smoke, no overheating, it just feels like it's misfiring.


Could these issues be related? I had the spark plugs and the coil on cylinder 5 changed (was getting an error code there), but that hasn't fixed the problem. My shop says the only other explanation they can think of is the head gasket.