Chrysler 300 metal expanding and contracting sound?
 

My 2010 Chrysler 300 Touring 3.5 V6 recently had new lifter assembly installed on the drivers side by dealership at 61,000 miles. The car is now making periodic metal expansion clicks until it comes to full temp, about 5 to 6 times. It then makes the same periodic sound when it is cooling down. At first I thought it maybe a heat shield but I have never heard a heat shield on a cat or exhaust manifold make the sound when it is heating up. Is it possible there may have been non-heat treated bolt installed when they did the lifter assembly? Could it be a sticking thermostat? The engine is running as smooth as ever even when it makes the sound.

Any help would be greatly appreciated.

Hi,
I still have the same sounds on warm up and cool down, about 30k miles later. The sound started after the dealer replaced the lifter assembly. When I complained about the sounds, they replaced my driver front cat converter, but the sound is still happens even today. The head mechanic at the dealer said he has heard the same sounds from a few other 300s and the mechanic school has no resolution. I have gotten use to it and have driven the car on x4 13 hour trips and x2 8 hour trips and it still is running perfect (knock on wood) but still has the same sounds that never goes away.
I was a backyard mechanic when I was young, even laying on the snow a few times. I think it is the heads or engine block or maybe a thermostat (that is buried under the intake manifold). I find it to be very relevant with the coolant temperature. I can make the sound by getting it up to normal running temp and then lightly rev the engine, when it hits 50% on the temp gauge it will pop again. Then it will pop again when it comes back to normal running temp. The dealer did not think so and said they would call if they ever found out what the issue is. I think they tossed their hat in after the new cat did not fix the issue.

I gave up worrying about it after running the car straight out on the few long trips with no issue or changes in the sounds.

Good Luck with your car. If you ever figure it out, I would love to know and maybe just maybe tell the dealer.

PS: My boss is an old Fastener/Bolt guy who never heard of metal popping when it is warming up... I still think it is the thermostat but do not have the $250 to try it out...