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Re: <small-six block coolant....> tech tip

     
     Subject: Re: <small-six block coolant....> tech tip
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     Originally Paul Reitz stated:
     
     (after drainig the coolant system)... add all the antifreeze required 
     *first*, then fill the system with water, since you can't tell exactly 
     how many quarts, total, you'll be able to get back in...
     
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     Eric Tangen replied:
     
     It is _much_ easier and far more accurate to dilute the antifreeze 
     with water prior to filling the cooling system... Plus, your leftover
     antifreeze is at the proper dilution in case you have to top the
     cooling system off.
     
     =====
     
     Eric's hint about the leftover a/f (antifreeze) being at the proper 
     dilution is accurate and convenient. But Paul's original point was 
     missed. 
     
     Scenario: You car holds 10 quarts of coolant according to the manual. 
     You remove the radiator and block drains collecting only 7 qts (3 qts 
     are always trapped in the bowels of the motor,hoses, heater core). If 
     you refill with plain water (twice is nice), to flush and then drain, 
     there are 3 qts of essentially plain water in the motor. If you then 
     refill with 7 qts. of premixed 50/50 a/f, there is only 3.5 qts of a/f 
     in the cooling system (there should be 5). This results in a 35% a/f 
     resultant mixture instead of 50%. No big deal for the tropics or 
     warmer climates, but potentially a problem in frigid locations. Plus, 
     there isn't as much waterpump lube and corrosion inhibitors 
     circulating in the cooling system.
     
     Resolve: After draining and flushing, first fill with 5 qts. of 100% 
     a/f (or whatever half of the total cooling capacity is per the 
     literature) then top-off with 100% water (as Paul originally 
     suggested).
     
     I'll also add:
     
     Don't be cheap. Use distilled water for the final water fill and 
     perhaps for the 2nd flush. A few dollars invested in distilled or 
     deionized water can pay-off in the long run (much better odds than 
     from Publisher's Clearing House).
     
     If don't know how much coolant actually drains from your cooling 
     system, measure what's collected the next time you do a cooling system 
     service. Just about every vehicle I've owned (not many were BMWs) had 
     at least a quart of two of coolant that never drained.
     
     Barry Ritchey
     '90 325iX, 106K