Hello JERRY CHRISTIANS,
Sometimes it can simply be corrosion in the radiator. As the anti-freeze degrades over time, you can get sludge build up in the radiator.
Since it doesn't float the particles must have some weight to them. Oil or transmission fluid would float. So, it much be metal or gasket material.
If you have an Infared thermometer, (see image), take measurements at both sides of the thermostat to see if it is opening. I am sure it is because you just changed it, but best to check just in case, even new parts can have issues.
If you don't have one you can get one either at your local auto parts store or hardware store.
If that checks out, use the thermometer and take readings on one side of the radiator and then the other. If there really isn't much of a difference in readings, then the radiator might have a clogged or restricted passage(s) causing coolant to not flow properly and cool the engine.
An efficient radiator will drop the temperature of the coolant approximately 20 degrees Fahrenheit from one side to the other.
Also, have you added any other auxiliary coolers in front of the radiator or a new grill? What is the condition of the condenser in front of it? If this is clogged with debris, air won't be able to pass through.
A good test is to warm up the vehicle and with the fans on, place a piece of paper on the grill. The fans should pull enough air to hold the paper in place.
Hope this helps.
Thank you,
Brendon
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Monday, July 31st, 2023 AT 11:41 AM