Fresh Water pump will not prime in Engine

[crazyhorse77]

I set out to do a good thing and flush the coolant (rusty water) from the engine, yet now the fresh water pump will not pump any water. hmmm
The engine is a mercedes OM636
What was done:
Emptied the heat exchanger
Ran the engine for 20 seconds to pump out water in block (now i think this was a bad idea)
Filled the heat exchanger back up yet no water is pumping around and the engine overheats in a few minutes.
I have removed the thermostat to see if it was blocked yet it was not and hot water was on the engine side on it.

Cause of the problem ???? I was hoping you could help me out here
Maybe a air lock ???

Solution ???

Many Thanks

Jarvis

[Mark1977]

Sounds air locked to me. You can try opening a hose at the highest part of your cooling system, and try to fill the system again. That may allow the air to escape. Sometime. just loosening a hose clamp high on the system will work. Good luck.

[crazyhorse77]

Originally Posted by Mark1977

Sounds air locked to me. You can try opening a hose at the highest part of your cooling system, and try to fill the system again. That may allow the air to escape. Sometime. just loosening a hose clamp high on the system will work. Good luck.

Thanks for the advice, I will try that now

[Unicorn Dreams]

Alot of engines have bleeders in top of the water jacket for that purpose, also you can pull the temperature sensor as you fill the engine with antifreeze.
Also, if the water was that rusty, I would check the impeller and was the thermostat open when you checked it, if not replace...

[doug86]

do you have a water heater that taps into the coolant circuit? If so, you may have to bleed air out of the water heater too.

[Unicorn Dreams]

Good point Doug86, forgot about that.
Also, fresh water pimp should not have to be primed, water should always e in the pump, just likes been posted it's the engine cooling system not filled...