He said 30k up there somewhere...

 

30 thousand K and a blown head gasket? I hope that gasket was a manufacturing defect.

 

If the thermostat stuck, then the engine's heat hasn't got anywhere to go hence the weak point will fail.
I can't remember if we have a cast iron block and alu head - if so the different rates of expansion will cause the failure at the join (head gasket) under these stressful conditions. Even if it is alu:alu the head gasket is likely to fail.

You're lucky (I hope) if it got too hot, the alu head is likely to warp at the mating surface to the head-gasket requiring it to be machined flat again - I'd hope they measure the flatness when they take the engine apart.

 

It happens with steel block steel head combinations too. The 3.8 is not reputed to have blown head gaskets as common problem. We have to be careful not to extrapolate ONE (or even a few) occurance to a trend that is going to cause us all problems. Nothing mechanical is perfect.

Having said that I just added a thermostat to my trail spares list.

 

Yeah, i think the failed head gasket was from the failed thermostat. I guess it was a good thing i was waiting for somebody this weekend and let my jeep idle for more than 5 min. Or else, i would've never find this out, and it might be to late then.

Still haven't heard back from the dealer, but hopefully nothing worse than replacing head gasket - no crack head or something. At least they're all under warranty. I just hope that they do a good job fixing it.

 

Correct me if I'm wrong but thermostats are "supposed" to fail in the open position.....yes?

 

I'm not sure about what's in our JK's but in older vehicles that I have owned I have had thermostats get stuck closed.

One allowed the pressure to build up until the top hose blew off. This was before the days of recovery tanks.

I know you can specificly buy fail open themostats. They cost more. $8 vs about $4 last time I bought them.

 

I guess in order to save $4 they decided to put the cheap one in. To bad they tend to blow head gaskets! Fools!

 

I believe if they failed in the open position the vehicle would not overheat, failing in closed position will make the antifreeze not circulate threw the radiator causing the fluid in the engine to overheat.

 

Well, they said that they're having the Chrysler Rep to come out there and take a look at the problem. I mean, these are the same engine they used in their minivan, and they lasted for hundreds & thousands of miles before they go bye-bye.