After coming back from a 350 mile trip to San Francisco something very strange happened to my 2015 Z51. Pulled into my driveway after the long freeway run in fairly cool weather. As I prepared to stop my HUD told me to not shut car off because it was too hot. As this happened I started to see steam coming from engine compartment. Next my HUD says that I need to change oil soon (I just had it serviced and reset before I left on trip last week). So thinking engine was having a problem I shut down car. I get out and open hood to see Radiator fluid pouring down driveway. I look over the cap and surrounding area to try and understand what is happening. As I move to driver's side I hear an explosion which sounds like a 12 Gauge shotgun going off. I turn around to see the radiator cap about one hundred feet in the air and heading out into the street. At the same time is a steam spout about 20 feet tall pouring out of the car. I was 15 seconds from being face over that cap! Well to make a long story short I had it towed in to the Dealer. They looked it over and said it was from an oval shaped spout on the coolant tank that caused it. I am not buying that but since it is under warranty and they said everything else checks out OK I am forced to live with there answer. They did say they have never heard of such a thing happening. Has anyone else experienced anything like that? My biggest concern is the extreme heat the engine was under.

 

Sounds like a bad thermostat, stuck in the closed position. That is just a guess......

 

There was a problem noted with a few C7 that did have a slightly oval, rather than perfectly round, opening in the expansion tank resulting in loss of fluid and subsequent overheating but I thought all of those were fairly early production models. This is the first time I have heard of the cap launching but with a severely misshapen opening not only could it allow loss of fluid over time it could also allow the cap to blow off under expected operating pressure.

It does seem a little odd in that your cap had to have sealed tightly at the time to allow it to build pressure but the leak could have been occurring as the engine warmed up but before normal operating temperature was reached.

This is one of the reasons I think "losing" the dedicated temperature gauge in the Z was a poor idea because cooling system issues will often show up as slightly but unusually elevated temperatures prior to anything bad happening. The Z06 puts the cute but fairly useless manifold pressure (more commonly "boost") gauge in place of the coolant temperature display of the Stingray model. I have mine set so it runs in sport mode display with the coolant displayed on a simulated gauge in the DIC area but in my opinion a much better design would be having the option of displaying manifold pressure as a pocket gauge while keeping the dedicated ECT gauge. Good instrumentation (and human factors) design provides the operator with convenient indicants of many potential issues while there is time to avoid/resolve them.

 

I do know of some cars that the radiator tanks have cracked and leaked. My 2016 had a bad thermostat that stayed open all the time.

 

Sorry to hear about that, sounds strange. Count your blessings that you wernt leaning over the cap when it blew off or we might be reading something even worse.

 

WOW....15 seconds.....just WOW!!!!!!!!!!!!

 

This happened when the bozos at the lube place filled my coolant tank and there was no room for the coolant to expand on my 1970 Chevy Monte Carlo SS 454 after running the car for about 45 minutes on a trip to a local car show !!! Wayne