Thermostat change - Need help.

[DeanMoriarty]

I need some quick help if anyone has advice.
Just changed the thermostat on 2.3 Ranger. When I started it up, there's in intermittent high-toned knocking sound, first it seems to come from near the thermostat, then it seems to move all over, change tone, etc.
The old thermostat had fallen apart and I'm worried a piece may have made it's way into the engine... even though I thought I'd gotten it all out.
I read a couple threads of people with air in the system causing it to make noises. If this could be it, how do I get the air out?

 

[MAKG]

Air noises will usually persist right after the engine is TURNED OFF! Since there are no moving parts then, it's a pretty reliable indicator.

If you think you got something in the water jacket, you can try reverse flushing it. Take the thermostat back out, pull off a heater hose at the intake manifold and cap the nipple. Then use a garden hose to force water through the heater hose. But frankly, I don't see how you can get a whining noise from debris inside the cooling system unless it's lodged in the water pump itself. I think it's much more likely something is caught in a moving part OUTSIDE the engine, such as in one of the accessory pulleys. Say, a missing bolt or washer? Maybe a hose clamp contacting something?