Heat Soak

[RedPhase]

I am having another starter problem with my 2012 RAM 2500. I posted about it a few years ago, took the truck off the road (Not reliable), and recently had the starter replaced a second time since owning the truck (December 2025). When I picked up the truck, it ran fine, and I drove it around town. When I shut it off in my yard, I heard the fuel pump and a thump sound. I called the mechanic and came back the next day, and the truck started with no problem. It is not my primary vehicle. It runs well, but still has a problem. I had the problem happen again when I shut it off at the gas station. I wiggled some fuses in the tipm, and it eventually started. I took it back to the mechanic, and he found a bad cell in the battery and replaced it. I have had starting problems with this truck since I bought it. The TIPM was replaced in 2021, and the starter was replaced at the dealer along with new starter wiring in 2023. Later that year, I fiixed the driver's side floor with new sheet metal, and the truck wouldn't start. I had it towed to the dealer, and there was a connector replaced to get the electrons moving. I have it advertised for sale on Facebook marketplace, and I got an inquiry about it and the guy asked me to try putting a heat shroud between the starter and the muffler due to Heat Soak causing the starter not to engage until it cools down. The man explained it and told me about heat soak.
The exhaust is too close to the starter, causing heat soak. Heat causes resistance inside the solenoid. That thump you hear is the solenoid slamming forward but not engaging, causing the starter motor to NOT spin.
When the starter cools down, that resistance disappears and allows you to start the truck again. I talked to the mechanic shop, and they think it is something in the engine. Something about the engine not turning counterclockwise manually. The guy from the shop says it isn't heat soak. I figured I would post the problem here for what to look for to fix the problem, or at least have it narrowed down, before I sell it. Sorry for the long story, but hopefully, that will give some information on owning a 2500 with phantom electrical problems.

 

[tron67j]

In no order:

You have replaced A number of parts, including floorboard which leads me to believe that there's a lot of corrosion going on there. My first guess would be that something electrical is not making good contact. Whether or not the incense of wiggling wires points to it being at that area or somewhere else, I can't say. My first step would to be take all the grounds off and clean them up really well and reconnect to ensure they have good contact. Then do the same thing for any hot wires, especially going to and from the starter. It might even be worth it to replace the hot wire back to the starter to eliminate that as a potential problem.

I don't believe heat soak is what that person from Facebook marketplace said. Generally, I've heard it referred to problems with either turbo intercoolers or just general air intake and not the problem where excessive heat causes mechanical components to non-function. Probably. I have to say I've also never heard of anyone having this particular problem with a Gen 4 truck where the the exhaust system is too close the starter, but if the exhaust system was replaced with a a non OEM part and it is not routed privately, there could be something your issue. Does it occur all the time where it won't start after extended driving?

I don't know what it means for the engine to not turn counterclockwise.

 

[markabby]

how's the ground wire? not the one on the battery.

 

[jawzs2]

try putting a heat shroud between the starter and the muffler

Pretty sure it's supposed to have one from the factory - at least mine does

Part # 56044116AE

 

[jws123]

Run a ground wire from your starter bolt/bell housing to your battery negative see if the issue goes away have had this on a few 2012s is it the correct way to fix it? No the real way is to find the bad ground but this will work.

 

[seems fishy]

You do not have headers do you?

 

[Wild one]

You do not have headers do you?

The Op hasn't been back since he made the post on Feb 25th