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Air in coolant

have air trap in coolant after water pump replace.cannot get it out.do i need to drain coolant again and start over.1997 nissan pickup 2.4 liter.

No, you don’t need to drain the coolant again, you just have to figure out how to get the air out of the system. Some vehicles have a bleed valve specifically for this purpose. Does your truck have such a valve?

Sometimes you can do it by parking the car facing up a steep hill and allowing the air to escape via the radiator cap.

Sometimes.

Who replaced the water pump?

Do you have a service manual?

the truck do have a bleed valve.do the truck need to be running or not.when i open the valve.

That’s why I asked if you had a service manual. A manual would have the correct answer to your question.

I don’t know the correct answer.

I’d try it both ways. What you want is to get the air out of the system. Anything that works, works.

Good luck.