I have what I assume is a coolant leak, but I cannot find out where the link is occuring. I read other posts that indicated if the leak was pooling under the floor mats on either the driver or passenger side then it is probably a heater core issue, but I don't have any pooling inside the cabin. When I inspect the engine I can't seem to see any residue on the block or around the overflow resevoir, although I can smell the coolant fairly strong. I had it pressure tested and the results said there was no leak, but later that night as soon as I put it in drive the "engine coolant low" message popped up on and told me to turn off the engine and refill with coolant. Luckily I had some on hand, but this problem is baffeling me and I was hoping someone could give me some ideas on where to look next?

do you see any white smoke when you start the car? if not, have you checked to see if your oil is contaminated with coolant?

Check your oil, and see if it is foamy in color.

Are you having any heating issues?

Have you checked under your car in your normal parking spots?

I haven't seen any smoke and when I checked the oil there didn't appear to be any coolant in the oil, however my heater isn't working as well as it has before I started experiencing these problems.

I have noticed a decline in the heater's ability to heat the car, but haven't really seen any leakage occuring in my normal parking places.

Hm...it definately sounds like a leak somewhere. Check your thermostat?

I reckon it is probably a leak in the radiator.

Agree, they always leak from the bottom of the passenger side (in LHD) of the radiator, have to look from under the car and pull the cover that goes below the radiator down to see it.

I took it to the dealership to have them do a pressure test. After two hours they said they could not find a leak. If the radiator was leaking wouldn't the pressure test show something?

i believe the coolant is leaking from the heater hose. that will probably cost you about $140 for the part plus labor.

Another place to look is the water pump, like te radiator some of these parts only leak when the engine is running and hot. you might also check the water pressure cap, if thats not sealing it can leak from there, parkup, with the engine hot and running and look under, see where the water is coming from.
Grendel

Thanks for the suggestions. I took it in and my mechanic said he suspects it is the water pump not functioning correctly. They did some extensive troubleshooting and it appears the problem isn't so much a leak as it is a blockage of some sort. So they are going to dig into the water pump today. Of course they asked if I wanted to replace the timing belt as well as the thermostat while they are in that deep into the engine. With over 130k miles on the car I figured why not, but the whole job will run me between $800 to $1000. More than I was anticipating, but hopefully will keep everything running smoothly at least for a little while.

I have the same problem with my S60 D5. What was the solution?