How to get ALL the rinse water out of cooling system when flushing it out?

[XC92]

This is a common dilemma so sorry if it's been asked and answered but I haven't been able to find a definitive answer. In preparation for replacing the water pump and thermostat (along with the TB, pulleys, seals, etc.) on my 1G Talon, I first dumped out the ancient coolant (properly, into a drain pan then transferred to large empty bottles that I brought to a local recycling event), then ran some Prestone cooling system flush through it for several days, then flushed that out with a garden hose via a Prestone Flush & Fill tap installed on the heater core inlet (or was it outlet, a shop installed it years ago). This was so the new WP wasn't subjected to any old coolant or crud.

However the TB/WP job took longer than I'd expected, and by the time I was done, when I ran some distilled water through the cooling system, it came out brown and cruddy again, almost certainly rust that had developed inside the engine cooling sleeves. So I ran some Thermocure through the system, and then just to be safe I then ran some diluted Evaporust through it, with the thermostat temporarily removed and the heater on hot and blower on high. Then I flushed the system with a garden hose attached to the heater core inlet/outlet and ran the car 5-10 minutes till the water ran clear.

Then, after draining the garden water, I put in some distilled water and ran that for a while, to remove any minerals from the garden water. Then I drained that, reinstalled the thermostat, and finally poured in some fresh coolant. (Note that I let the system cool down between flushes, especially when I ran garden hose water through it, so as to not crack the block.) I used concentrated coolant with distilled water.

Thing is, I know that when you drain the cooling system via the radiator petcock, some liquid still remains in the system, so whatever you add next will be diluted and even contaminated with it. That's ok when flushing the system, but for the final step, adding fresh coolant, how do you get as much liquid out before adding the coolant, so it's not diluted by it? I'm not worried about contamination because with all the flushing I did, with the thermostat out and the heater at max, finishing with distilled water, it's clean. But the remaining water is going to dilute the coolant, by how much, I'm not sure.

To compensate for this I used a 55/45 coolant concentrate/distilled water mix. But I'm not sure if that's enough. I have one of those cheap specific gravity-based coolant concentration testers, that I can use to add as much coolant concentrate as necessary to get it to 50/50 coolant/water. But is there an easier way to get it right the first time? Some engines have drain plugs, but I don't think 4G63's do. Anyway, just wondering.

 

[Mello]

Pull the little, short coolant hose to & next to the OFH cooler. Only water left will be a little bit stuck in the heater core which is little, or also pull the lower heater hose too.

 

[pauleyman]

It doesn't matter. If you absolutely need to nail 50/50 then use an antifreeze hydrometer to analyze what you have in the system and add coolant or distilled water to reach 50/50 and then Top off with 50/50. If I'm close and well within the temp range I need I'm good.

 

[XC92]

Pull the little, short coolant hose to & next to the OFH cooler. Only water left will be a little bit stuck in the heater core which is little, or also pull the lower heater hose too.

Thanks. It was getting late so I just drained from the petcock until nothing flowed, shut it, and added the 55/45 mix to the thermostat housing. I'll run the car with the heater blower on max till the thermostat opens, let it run a minute or two more, shut things off, wait till it's cooled, then check the specific gravity of the coolant to see if I need to drain it and add concentrate to get the mix up past 50%. But it's good to know for future reference.

Btw how often do folks here replace their coolant, and flush it? I tend to do it every 2-3 years, and run a rinse detergent flush to make sure everything's clean.

It doesn't matter. If you absolutely need to nail 50/50 then use an antifreeze hydrometer to analyze what you have in the system and add coolant or distilled water to reach 50/50 and then Top off with 50/50. If I'm close and well within the temp range I need I'm good.

Rarely gets below 0F here in winter, maybe -5 to -8 every few years. I think that 50% has me covered for that and then some. It also rarely gets over 100F in summer, also every few years. That may change, but that's a whole other discussion. I'll just check and add if necessary.

And with that, I'm basically done for the season. Maybe a few minor tweaks and fixes here and there, but for the big stuff, I'm toast.

 

[pauleyman]

I've had a hydrometer for years. Doubtful it's super accurate. So if I'm in range I leave it alone. I don't really care if I'm 45/55 or 55/45 etc. Unless I were in a climate with one extreme or the other.

 

[XC92]

Sounds about right. I was just concerned that a LOT of fluid was still in the system after petcock draining and the numbers would be way lower than 50%. But there's an easy way to check for that.