OK Guys, I'll try to keep this short, but I wasn't really happy today. I took the Jeep into the dealer this AM for our scheduled check-up of the leak in the coolant system. It has only leaked when I have run it hard and have broken the 155 MPH mark. So I tell this to the service manager as they are very understanding of high-speed driving here in Germany. I thought he would run a pressure check on the system and report back. I checked my mileage and fuel level before leaving the truck. The guy calls this afternoon and says that he tried to duplicate the leak scenario -- I asked; "how did you do that?" And in typical German fashion he answered "I took it on the autobahn and drove it to 155+ MPH." I was in a meeting in my office when he called so when I heard this I had to keep my cool. I asked him if he had my permission to do so and with perfect German logic he replied "How was I supposed to diagnose your problem without replicating the causal situation?" While he is right, I still wanted to reach through the phone and punch him. We worked out our differences later at the dealership, but I was one pissed-off Mo-Fo. I'm sorry, but a 33 mile "shakedown" run has my imagination SCREAMING!! It's like thinking about someone taking your woman for a "Spin". Not happening. Granted, he had to travel 8-10 miles to get to the autobahn, but I really would have preferred to have been the driver -- or at least the passenger! At least the bastard was alone and didn't have the shop dweebs with him. (Remember, mine is the first one of these here....)
So, the diagnosis from the head DCX office is that the radiator needs to be replaced. They said that it must have some blockage somehow. I asked why this only occurs at extreme high speeds and they are unable to give me an answer. Even though this is a warranty item I am not happy about this type of fix. I would rather take a little extra time for diagnosis than repair by replacement. They mentioned that there are no other cases of this happening, so they have no other frame of reference. Sorry for the long post, but if anyone has any ideas or suggestions, I'm willing to listen.

Thanks!! MJ

I know how you feel about them taking your car. I can't even stand leaving it to have the oil changed! When I dropped mine off the have a windshield fixed , I overheard the guy talking to another guy who was taking my car to have the windshield replaces " have you drive one of these before? "no" "Oh you will have lots of fun!" I about pissed myself.

About your problem, I have never heard of it and don't kno why only at high speeds would it be affected.

Have you ever looked at the temp guage during the high speed runs? Is the engine heating up too much & causing a problem? Maybe an airflow across the radiator problem?
This sounds like a continuation thread. How about a quick synopsis of the problem.

I just found your first post. A leak from the cap can be caused by numerous things...faulty cap, damaged rubber gasket seal area in radiator neck, excessive pressure inside the radiator, cap with too low a pressure rating, and the one that isn't good...a slightly leaking head gasket, to name a few. Some are visual checks, some can result from airflow cooling issues, and some can be detected by pressure testing & leakdown tests. The blockage that they refer to would limit the radiator's cooling capacity & cause additional heat inside the radiator which would, in turn, cause more coolant expansion & pressure.

After a blast down the Autobahn, does the vehicle have the opportunity to cruise for a while & stabilize the coolant temp to normal levels before being shut down?

I feel your pain. I just too my ride into the dealer to have a squeak and rattle from the rear area fixed. They said they couldn't hear anything by rocking the Jeep by hand, so they were going to drive around the dealer lot. When I picked it up, there were 8 more miles on the odometer and they still claimed they couldn't hear anything. I could just about punch someone because you don't have to drive more than 100 yards without the squeak happening. So all that they managed to do was have a joyride and lube the rear which helped all of 12 hours. I didn't have time to argue when I picked up the Jeep, so I need to go back to lodge a complaint with the service manager. Not that it will do much good.

I just found your first post. A leak from the cap can be caused by numerous things...faulty cap, damaged rubber gasket seal area in radiator neck, excessive pressure inside the radiator, cap with too low a pressure rating, and the one that isn't good...a slightly leaking head gasket, to name a few. Some are visual checks, some can result from airflow cooling issues, and some can be detected by pressure testing & leakdown tests. The blockage that they refer to would limit the radiator's cooling capacity & cause additional heat inside the radiator which would, in turn, cause more coolant expansion & pressure.

After a blast down the Autobahn, does the vehicle have the opportunity to cruise for a while & stabilize the coolant temp to normal levels before being shut down?
Hey LarryC777, thanks for the intel. Here is the scoop. The leak has only happened a couple of times - both after 155-160+MPH runs. The leak comes from the cap, which the dealer replaced a few weeks ago. It only looks like a few ounces, if that, leak out. Of course it blows over the engine bay. It is obvious that it originates at the cap. They brought the rig up to temp and performed a scan tool and checked all temps to make sure things were within spec. Everything checked out, even tranny temp. Again, the DCX guys said replace the radiator, but I really don't want to go there....To answer your other question, the Jeep gets adequate cool-down after hot runs.