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Coolant change procedure

I’ve just read through some old CTC threads on replacing coolant, and see there are (or were then) some varied opinions amidst the consensus. My 96 Grand Caravan, which sat for about 5 years until I adopted it last month (running quite well now, thankfully) is obviously due for new coolant and hoses. What I read in the old threads coincides more or less with what I’ve done in the past…some variation of drain radiator / fill with water / run till hot / drain again / fill with straight coolant to attain a 50/50 mix.

Considering that I don’t know when the previous owner last changed the coolant, and especially considering that the engine didn’t run much for five years and not at all for three, do I need to do anything more than this somewhat standard exchange method? I have no burning desire to use chemicals or pay for a pro service. I do have one of those gizmos to hook up the garden hose for a flush, but that produces so much volume of liquid to take to our recycle facility…I’m reluctant, but willing if that’s what this situation needs.

Instead, I was wondering if there’s any benefit from a variation: drain / fill with water and drive a day or two / drain and add a gallon of green / and then drive it for a week or two / then repeat that a second time and replace hoses and thermostat. Or am I better off with the more conventional: two refills with water and only one dose of pure antifreeze, ending at 50/50? I don’t mind the cost of a second gallon if it’s some benefit in this situation, but certainly won’t bother if that’s just a waste of money.

Weird as it may seem, I like this car and am likely to keep it a while, so don’t mind a little extra effort to help overcome any issues that may exist after the long slumber. It’s a 3.3L V6, 152k, previous owner seemed to have maintained it fairly well.

Thanks for any thoughts!

Personally, I would just open the drain on the radiator and block, drain all that will come out, close the drains and refill with a premix of coolant and distilled water. By premix, I mean that I premix my own but you can buy it already premixed, but that costs more. I don’t like flushing cooling systems.

I would say you are overthinking this situation, trying for an optimal solution that is hardly necessary.

A car’s cooling system is a simple plumbing arrangement. Maintenance does not really require anything more than a drain and refill. A single intermediate rinse might be beneficial, but is not mandatory. Any traces of old coolant that remain in the system are of no consequence.

Choose the simplest or most convenient solution for yourself and consider the job done. Some of us go further because we have the time and ambition, but additional flushing is not going to accomplish much, if anything.

I agree with SteveF with the exception that an intermediate rinse allows various contaminants into the system, such as minerals and chlorine. If it doesn’t need it, I would not do it. Keep it pure and simple.

I’m with Steve on this.
Typically what I do is turn the heat on, disconnect the lower radiator hose, drain the system, replace the hose and refill the system with fresh mix, run the engine to full temp keeping the heat on, top the system off, and take it for a test drive. Then I let it cool down and double check the level.

If the old cooolant seemed less than clean, I might do a hose flush somewhere in that process, but I prefer not to introduce minerals unless necessary, even though I realize the amounts will be tiny when I’m through.

I avoid chemicals unless there’s a really pressing reason to use them. IMHO a clogged radiator needs replacing, not chemical cleaning.

Thanks all. I’m glad to make it a little easier.

Typically what I do is turn the heat on, disconnect the lower radiator hose, drain the system....

@ mountainbike: I need a little clarification - I don’t get the point of turning on the heater, given that with the hose off and the system draining, the engine is not running. Does this open a water valve to the heater core thus enabling a better drain of the system? I was thinking that the heater control only managed the air flow doors in the cabin, but maybe that was only true 40 years ago.

Yup, it opens a water valve to better drain the system and better purge the heater core of air. Leaving it on basically compensates for my poor memory. I’d probably forget to turn it on otherwise.

Not all cars have such a valve. But many do.

Great, thanks.