Thermostat and coolant color question

[20RamTradesman]

I got a 2020 ram 2500 hemi 6.4 check engine light came on during the week and called a thermostat code. We got it replaced and light came off. Never overheated or anything. I was checking out today because it smells like burned coolant and I found the coolant tank had brown or black burned ring around it and was no longer filled at max. OPEN TO SUGGESTION, Thank you.

 

[GTyankee]

Just wondering if you replaced the thermostat with the OEM Mopar unit ?

 

[pacofortacos]

You might want to check for leaks, if you smell it, it is probably leaking somewhere.

 

[Rlaf75]

Who did the work? If you're smelling antifreeze then more than likely there's a leak somewhere. As far as not being full to the max line, that could be an indication that there's a leak or that it was never bled properly and it finally bled the air out and sucked the coolant in leaving the tank low. I'd recommend taking it back to whoever did the work and have them pressure test the coolant system to check for leaks

 

[crash68]

The 6.4 Hemi has an EGR cooler, you usually won't see anything leaking from them. The coolant either goes out the exhaust which plays havoc wreck with the catalytic converter or it goes down the intake which can end up in the crankcase oil or cause hydrolock.
Get the engine warmed up before pressure testing as the leaks sometimes don't happen cold.

 

[Burla]

They do have coolant testing services to check for oil in case the issue it a gasket, and for sure I would top off and run rmi 25 it will take any slime in system and deposit in overflow where it gets trapped til you remove it. Top off and check it everyday for a while. read about rmi25 here, the reason I recommend it because I had dex damage from someone putting dex into an old iat radiator system, cleaned it right upo and my over flow was full of slime. No need to add coolant with rmi 25 at this point, you can just use distilled water and the product, it is concentrated coolant and detergent made just for this. In a couple weeks after you do this, flush the system. rmi 25 might even have leak detector, I';m not sure about that, read that page.