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Coolant flushing/changing

1K views 6 replies 3 participants last post by  nicholassheppard 
#1 ·
Hi, I own a vauxhall zafira dti elegance on an x registration plate. I have a haynes manual and have bought 8 litres of ready to use coolant, I know where the drain plug is etc. The question i would like answering is, do i let the engine coolant get up to temperature with the interior heater fans on hot and on full and then drain, to remove the coolant in the block or drain and replace when cold?

Also do you recommend flushing the system with cold clean water and how is this done?

Sorry for the question
 
#2 ·
Do it cold or you could do yourself some damage as the system will be under pressure and v. hot.

Flush with a hosepipe (if you don't have a ban in your area). Can also buy a product specifically for the job; it's an additive you add to the system after you've drained all the old coolant and refilled with water. You can then drain the water and additive out and refill with new coolant.
 
#3 ·
god no, dont do it hot, or a trip to the hospital may well be on the cards, as said do it when the car is cold. unless it is unusually dirty, why are you changing the coolant? yes its good practice, but unless its totally filthy, or the car has recently had a head gasket and there is still millky crap in the system i dont see the point.
 
#4 ·
Thank you for the replies, my car is just about to have completed 100,000 miles, the only reason is to keep on top as a preventative measure.

If the engine is cold and so is the coolant, if i drained the coolant would it still leave coolant in the engine block area if that makes sense as the thermostat would not of opened so not circulating. If i put the new ready to use coolant in, wouldn't this dilute the mixture ?

Thank you for any replies

Nick.
 
#6 ·
To flush the coolant properly, you should remove the thermostat.

If you don't want to do this, flush using additive (as per instructions on the label). This should help remove any deposits. If the existing coolant is in good condition, this shouldn't be necessary.

It is not possible to remove all the coolant from the engine block (or the radiator unless you take it out and turn it on it's side). For this reason, it's probably better to use a concentrated coolant/anti-freeze; you can fill with the required amount of coolant (for example 50% of the total coolant system capacity) and then top up with water.
 
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