How did you find out about this broken head gasket? Was it simply coolant level slowly going down or were there also other hints (quick coolant loss, white smoke, coolant smell in exhaust fumes, engine running rough)?

There are a few members here on the forum that report very small coolant loss over time (think: refill two glasses per year/6k miles), coupled with a faint smell of coolant in the hot engine bay. However the mechanics are unable to identify where the coolant gets missing, even after repeated pressure testing. I am one of those members.

br ter

The first red flag was if my car set for several days wo running, soon as I started it up it would blow thick white smoke out the exhaust for several minutes before stopping and definitely smelled like coolant. Then it started misfiring, and going into "restricted performance" mode, or something to that extent. The final step was the low coolant light, followed by motor overheating. That's when I shut it down, had to towed to performance shop, and all the above repairs mentioned done. Just shy of 10k in work to get everything squared away. Took me driving it almost another 30k miles before any other issues were had. Which makes me think that my low coolant light now isn't a big deal, maybe just some had dissipated off from all the driving I've done.

Count me in as another member with the same symptoms. Over 6 years, coolant smell after shutting off car on a 20 minute drive and adding small amounts of coolant over time. No leaks anywhere or pressure loss.

This just started to happen to me this week as well. I haven't gotten it pressure tested yet. I smell the smell but can't find any leaks yet. Fortunately, knock on wood, the oil looks fine. 2014 Touring, 47K miles.

How do you check the oil without a dipstick?

Sucked some out with my oil extractor
CC

Modern radiators with plastic end tanks are a bit notorious for failures. The dealer is almost directly across the street from my office. I walked over to have a look-see at the culprit when they called to offer the news. Plain as day, the passenger side plastic end tank was popped loose from the core. New radiator in, fluids flushed, etc. and away I go.

Feff

Well, radiator and half a dozen coolant hoses replaced, but water pump number 5 installed as well. That's three in the past year. It hadn't developed a leak yet, but a nipple or connection to a hose within the pump had deteriorated enough that it would not have lasted much longer. I made my independent mechanic cover the water pump under warranty because twice last year was all I was willing to pay, but it's still frustrating how fragile these things are.

What happened to the radiator ?

DannyJ,
Had a few drops of coolant on my driveway for about a week and would have to add a couple of cups of coolant every other morning. I took it to my mechanic who found a small leak in the radiator and while there replaced 4 hoses that were on their way. I can't complain too much as the car has almost 160,000 miles on her. Got her back yesterday and all is well so far.

Good to know Tberg
I'm at 125 Kmiles and started to be worried about radiator condition although coolant level is constant

Danny

Last night after going out to dinner, I went to start my car and the dreaded low coolant warning started flashing.. Fortunately, I had two gallons of anti-freeze in my trunk, and it swallowed over 1.25 gallons. At that amount of loss I wasn't sure I'd make it over the hills back home but I figured if I had to stop and fill it along the way I would. I didn't want to leave it overnight 20 miles from home. I made it home without incident and the aux. fans never went on so it wasn't running hot, and today it's going back to find out what the hell is going on.

Don't they test drive the car before giving it back? Or do they just take it around the corner?

Do a search on this question and you'll find people upset that miles were added to their car.
This will vary from place to place.
Some will make sure it holds up to real world conditions by taking your car to Home Depot and picking up some lumber.

Ter11, how many times do you twist the cap after it starts clicking?
How old is the cap? A cap that isn't working as it should won't hold adequate pressure.
Steam is a matter of pressure and heat, lower pressure, and the flashpoint of the coolant also lowers.
It could be as simple as your radiator cap.

The car was run for over an hour with no loss of coolant when I picked it up. After I filled it up last night in Beverly Hills after the warning, I drove home over the Santa Monica Mountains about 15 miles to home, checked the coolant level this morning, and it was full. I just spoke to my mechanic, and he was short of help today so he couldn't pinpoint the problem, however, in pressure testing he says it is losing coolant and suspects one of the hoses under the supercharger, not a pleasant repair. We'll know more tomorrow, I hope. I miss driving my XKR when I don't have it, but today, I pulled the Pantera out for duty and drove back to Beverly Hills and back. Thrilling!