Hi everyone, I am gonna perform a coolant change on my car, it’s not that bad I am just changing it when recommended so I don’t think there is a need for a flush. (where you use water and chemicals) However I want to do the job right, and if I just drain the radiator and reservoir. I really don’t like the idea of having old potentially contaminated coolant that is still in the engine block and getting mixed in.
Is there a way to drain the engine block so I get fresh new stuff in? So I don’t mix the old stuff. It’s like cleaning you’re windshield super good, only to have muddy wipers that spear mud on 2 seconds later
Sweet thanks, and i’d assume to refill the block with a pump (or fill bolt?) before doing the regular radiator fill and bleed process, that way it’s not running dry. Or would you say that’s not necessary
Assume the block drain will be difficult to impossible to remove.
Don’t worry about leaving some coolant in the block. What you are doing is not draining dirty fluid as much as adding fresh corrosion inhibitors and water pump lubricant.
Agreed. Drain from the lower radiator petcock and/or lower hose. Most of it will come out even from the block. If you haven’t neglected the system, then there’s no need to think of whatever little bit of coolant left is “contaminated.” If there’s no need for a flush, then there’s no need to worry about getting every last drop of the old stuff out.
If you do want to soothe your anxiety, drain it out from the bottom of the radiator, do one refill with just water (no chemicals or “flushes”), run the car until hot. Once it’s completely cool, drain, refill with the 50/50 mix, make sure it’s bled, and drive on without worry.
Unless there’s a major problem with your car’s cooling system, or the coolant is incompatible with your new coolant, I wouldn’t worry about it. That assumes you know what kind of coolant is in there now, and you’re matching it with the replacement coolant.
That’s how I do it. Note that you may not have enough room to re-fill with 50-/50. A recent thread here addresses that problem. You can find it using the forum search
The coolant generally doesn’t get contaminated. The corrosion inhibitors wear out and need to be replenished. I don’t see what kind of vehicle, year, miles but it doesn’t matter as long as it is getting its first refill on or before it is due or the cooling system maintenance has been kept up to date since new.
Most preventative maintenance schedules for the cooling system have a first service with a pretty long interval from new. Second and subsequent service intervals are closer together because the engineers knew that some of the old coolant would still be in the system. The intervals are based on a drain and refill with factory spec coolant. No flushing of any kind.
Your 50/50 mix has antifreeze, inhibitors and purified water. The water has no minerals in it. If you flush with clear water from your hose, it will have minerals and some of them will remain behind. That will shorten the life of the inhibitors in your coolant. The remaining old coolant is far less damaging than a garden hose flush, and far far less damaging than a chemical flush.
If your vehicle is over 10 years old, you may want to replace the thermostat. They get lazy over time and to replace it next year will mean an early coolant exchange, so it is best to get both out of the way now. If your vehicle is approaching 20 years old, then replace not only the thermostat but all the rubber hoses, (radiator, heater and any of those little misc rubber hoses like to the throttle body or intake manifold).
BTW, you do not need to drain the block, there isn’t much coolant in it anyway, more work than it’s worth. The residual coolant in the block was accounted for in the PM schedule.
