I have a 91 ford Explorer. Coolant hoses jerk and make a popping sound when I turn off ignition.

What may be happening is coolant boiling inside the engine once water circulation stops. Your coolant may be weak. Try flushing the radiator out and putting in new coolant, 50% water and 50% anti- freeze.

If you have an electric cooling fan, make sure it is working properly. It should run for a couple of minutes after the engine is shut off when the car is hot.

Thanks will try, but also this occurrence is more when I run the heater, so plausible but I have also been reading that it never came with a heater control valve and that maybe a contributor but no one has confirmed this.

Thermostat has a jiggle pin I think as spring was wobbly and could be depressed by hand. Replaced tho and system was supposed to be bleed as it was done by my mechanic but it worked fine the first day then not so much. Changed heater core but did not receive bleed. Tomorrow I will go to a friend's house to flush radiator as my outside water was cut off per landlord... Lol

No

Flushed system found out hoses were not as tight as they could be, tightened , then placed on an upward slope after running it for a while around the corner then waited for 15 minutes Then loosened radiator cap and burped. Did this same process until air finally left system. Now I can drive with the heater on Thanks for every one's imput, very useful.