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I have a 2005 Mazda Bounty UTE. How often should it have a coolant flush?

I have since seen videos which suggests a flush should be a number of cycles of empty, new water, empty, new water, empty etc until clear. Then new coolant.

Is that what a mechanic does when they do a flush? Is that really necessary or will an empty and refill with new coolant offer enough benefit?

  • It depends on why you're doing the "flush". Usually you can just open the radiator and block drains and refill. – Ben May 30 '18 at 22:28
  • I have had the vehicle since 2011, and it has not had any flush. – peter May 31 '18 at 0:15
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This is a slightly difficult question to answer, as the amount of time between flushes depends heavily on what kind of car you have and what kind of coolant your car uses. You should be able to find the coolant replacement/flush interval in your owners manual or service manual.

In terms of the flushing procedure, this is what I like to do:

  1. Obviously, start by emptying all of the old coolant (generally there is a drain plug at the bottom of the radiator).
  2. Then, fill the cooling system with distilled water, optionally you can add radiator flush chemical as well.
  3. Start the engine and allow the water to circulate through the car, racing the engine a little until it gets up to temp.
  4. Empty the water and refill with your new coolant.

Steps 2 and 3 can be skipped if your car has a short coolant replacement interval, but I'd recommend to always do them if the car has a long coolant replacement interval or if you are changing to a different brand of coolant.

  • Thanks. Did you ever have a problem with getting the air out of your system after the coolant flush? I once killed a water pump after a flush, but don't understand how. – peter May 31 '18 at 1:13
  • @peter generally leaving the coolant expansion tank during the procedure is enough to get any air out of the system. – WeakMech May 31 '18 at 1:44
  • You mean leaving the expansion tank empty until things have settled down? Air isn't going to kill the water pump though right? – peter May 31 '18 at 1:48
  • Sorry typo, I meant leaving the coolant expansion tank CAP open during the procedure. – WeakMech May 31 '18 at 1:51
  • Air should work its way out of the cooling system during the flush, it shouldn't kill the water pump. – WeakMech May 31 '18 at 1:53

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