Replacing thermostat/housing combo.
Removed the unit from the front of motor.
The housing came off no problem, but the thermostat stayed stuck in the motor.
The thermostat doesn't seem to want to come out unless I put some force on it.
I was wanting to check to see if anyone else might have ever had this problem and also what is the best solution to remove the thermostat without me doing damage to anything.

Thermostat stuck

 

Channel locks. Grip the end of the spring assembly and gently move it up and down, side to side. It will pop right out.

 

I tried that, as well as vice grips and a few other things. Unfortunately that didn't work. I appreciate the advice though. The advice was good, but the situation was not lol. This worked though!...
Had to put my weight behind it too!

 

There is no reason for that sticky debris build up except a previous owner added something to the coolant, possibly to a stop leak additive. The approved coolants and even mixing in non approved “universal” coolants will not cause this. You might want to pull the radiator and inspect it for blockages and do a flush of the engine block and head to avoid hot spots.

 

I'm currently having the same issue on this m272 3.5L engine. After seeing this thread, I might try again tomorrow.
Also what would cause this white stuff inside this engine came from a wrecker but I bought as a replacement engine. Should I be concerned after seeing this? I might replace the water pump and try to flush the block.

Thermostat stuck in housing. Plus white stuff
Also, I noticed there was silicon. The previous person that worked on this used silicone on top of the gasket?!?!

 

That looks like what happens when hard tap water is used instead of coolant. You’re definitely going to want to flush the engine. Drop a piece of that white stuff in water to see if it will dissolve. If it doesn’t you’ll need an aluminum safe flush agent.

Of course, if the previous owner was low knowledge based on the silicon on the gasket, there’s no way of knowing what was dumped into the cooling system.