Yes, that's why it's called a lock
The thermostat may have been installed backwards. It only opens one way. problem solved it was caused by an air lock thanks.
Attach an auto air vent at the highest point on the line
more than likely an air lock on your water system it will need bleeding to release the air lock if that fails try replacing the thermostat
you have an air lock in tank , which will stop fuel going from tank its nothing
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Wrap it in a blanket ? Seriously - if it's 'shuddering' chances are there's an air-lock somewhere in the system. You just have to leave the tap running for a while until the air-lock clears itself.
The 15 horsepower Mercury outboard motor does not have a water pump. The outboard motor is air cooled and does not have a need for circulating water.
air lock in hot water pipe
Coolant mixed with a little air circulating thru the heater core. Check the coolant level in the reservoir.
The acronym for Air Lock is A/L.
By installing a Hoffman #75 air bleeder up to 75 PSI.
through wind and circulating air.