I changed the thermostat and temp. sensor in my 2000 S40 about 3-4 months ago. Car ran fine but then the upper radiator hose failed and leaked the coolant out. I replaced the hose and refilled the system, but now the car never seems to quite reach operating temperature. At first, I thought there may be a leak and the system was unable to keep pressure, but I am not losing any coolant, and it seems to keep pressure fine. The next thought that I had was that maybe the thermostat got messed up when the hose failed and is somehow stuck open. Any other ideas to look at?

 

I own a 1999 s70 awd. I was having the issue of my engine temp gauge not reaching optimal temperature...

I noticed my coolant was low. I didn't have any so I put water in and it seemed to work. It was also taking like this morning 30+ minutes to finally get to optimal temp when it would get to optimal temp.

I had an appointment at a shop and they found nothing leaking and I told them about the thermostat but that didn't say anything about it good or bad.

They flushed the system because there was actual sludge in the coolant tank. When I left the car got to optimal temp quickly.

We will see if it stays this way. I smell a sweet maple syrup smell coming from the vents and I believe if it is leaking that it is leaking at the heater core. Which when the tech priced it out was well over $500 to do.