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Discussion Starter · #1 · (Edited)
Hey guys,

As you may or may not be aware, my coolant overflow tank cracked and sprung a leak. I figured out the parts to buy and I'm about to replace them, so I thought this deserved another thread.

I was reading this thread, but I am confused about several things. My main concern was at step number twenty. He begins adding a 50/50 antifreeze mix to the system "until the blue mixture drains out," as he states. So, he is essentially using the 50/50 mix to displace all of the distilled water in the system. Using this method, it's not clear to me how he ended up with what he considered to be the right concentration of antifreeze in the system. That had me thinking. If you flush it out with distilled water you don't know what kind of mixture you need to pour in so when it mixes with what's inside the car it becomes as close to a 50/50 mix as possible. And you're not going to be able to drain all the fluid out anyway. Why not just drain the coolant until it stops dripping out, make a 50/50 mix, top off the tank, turn the car on and pour more in until it stops sucking it from the tank? What's already inside my car right now is hopefully a 50/50 mix (don't know what the previous owner did but no issues). Yes you'll be mixing old coolant with new coolant but that shouldn't matter right? I'd rather have old and new 50/50 coolant mix together, rather than not getting the mixture right if I flush it out with water. It seems a lot simpler and safer. And I think I read somewhere that Volvo recommends doing this way because flushing it could cause potential harm to the vehicle.

So what do you recommend, a full flush or drain and fill? This is the biggest maintenance task I have ever done on a car before so I want to make sure I understand what I'm doing. Also do I have to worry about burping it once I'm finished filling it? How would I do that?


Thanks!
 

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How old is your thermostat and hoses? If your antifreeze is not brown or very filthy, you should just drain it and fill it with 50/50. If your thermostat and hoses are old, you may want to consider replacing them being that your draining the antifreeze already.
 

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This is a valid point but a bit overstated. This same question comes up when doing almost any kind of fluid replacement. Auto trans, power steering, even engine oil. The perfectionist in us all wants every spec of old fluid out.

Coolant replacement is no different. As ryjimenez17 pointed out, if your old coolant looks good a simple drain & fill is perfectly fine. If it's filthy I think it's worth going a bit further. Personally I "flush" using my garden hose until everything comes out clear. The flush Volvo warns about is a power flush using a machine & harsh chemicals. Remove the coolant tank, open the radiator drain, open the block drain, pull off any hose you can easily get to & run the garden hose down each opening. If you have compressed air you can follow up by blowing through each connection as well displacing most of the water. Close it up, add your mixture, add an extra cup or so of coolant & call it good. There is no special burping or bleeding procedure necessary with our cars.

Is some tap water left behind? Sure, I find this preferable to old coolant however. You can use the original Sticky directions if you want a more pure & perfect result. The key here is to open the block drain. If you don't there will be a significant amount of old coolant or water left behind making it hard to guesstimate how much coolant to add.
 

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I remember that this was the first things I ever did with my car too, other than an oil change.
if you follow that write-up youll be alright but now that I've had to do this twice, I found that it can be a pain. I'm not sure where the drain for the the block mentioned above is.
But without having to take too many things apart, you can remove petcock on the bottom of the radiator... drain the fluid and measure how much comes out. IIRC the capacity is 9qt. So youll probably only get about 5qt's drain out, so you know there is still 4 qt's inside. Now fill with garden hose while the engine is running. and either keep the car running or fill and drain with tap water until its all clear coming out(or you can use distilled, which is what i did). Now, Remember there is about 4qts left inside(you can measure what comes out again if you want) So pour in 100% coolant (in this case, 4qt's) and then fill the rest with 50/50.

Ideally its be easy if you could get everything out of the engine/core. all I can say is dont sweat the details of this whole process too much. its not that serious.
 

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Last time I drained the coolant I did it by draining the rad with the petcock and then draining the engine by disconnecting one of the coolant hoses on the oil cooler.
 

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Discussion Starter · #7 · (Edited)
Not sure about the old coolant guys, there's barely any left in the tank after it cracked. It actually looks somewhat clear if you look down the hole of the tank. I'll find out when I start draining. Not sure how old these parts are since I bought the car used almost 3 years ago. No idea if the previous owner did anything.The capacity of my car is 10.5 quarts.

That being said I have limited tools and knowledge. Once I completely flush it with water, how do I know I have exactly 5.25 quarts of water in my engine, and shouldn't I pour it in premixed instead of pouring the antifreeze in after the water? For someone like me who is not experienced at all and doesn't trust myself, I think the drain and fill sounds more safe, although less ideal. I know this isn't too difficult, but I have no way of knowing accurately how much is in my car and how much I need.
 

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Here's the easy way - drain as much as you can out prior to warming up the engine. Then place garden hose in radiator cap opening and turn the water on slowly. Start the car and leave the radiator petcock valve open. Watch for the thermostat to open and then watch for when the fluid coming out of the petcock valve to turn clear. Ta-da, completely flushed of all old antifreeze. Now close the petcock valve, pour full strength volvo antifreeze in the radiator and overflow tank (remember you can only get about 50% out, so the remaining water will mix with the full strength antifreeze and give you a 50/50 mix). Check the antifreeze level over the next few days as the air burps out of the system and add water or antifreeze as you see fit. You're done.
 

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Discussion Starter · #9 ·
Here's the easy way - drain as much as you can out prior to warming up the engine. Then place garden hose in radiator cap opening and turn the water on slowly. Start the car and leave the radiator petcock valve open. Watch for the thermostat to open and then watch for when the fluid coming out of the petcock valve to turn clear. Ta-da, completely flushed of all old antifreeze. Now close the petcock valve, pour full strength volvo antifreeze in the radiator and overflow tank (remember you can only get about 50% out, so the remaining water will mix with the full strength antifreeze and give you a 50/50 mix). Check the antifreeze level over the next few days as the air burps out of the system and add water or antifreeze as you see fit. You're done.
Sorry didn't see this reply before we did it, but I did it with my dad. He's not a mechanic but used to work at a garage back in the day and has done a lot of work on cars on the side. He didn't want to flush it out because he was afraid we weren't going to get the right mixture because we didn't know how much water would be in the engine after it flushes. It didn't drain like he thought it was going to, and he didn't think it was going to be a big deal because most of it is new antifreeze. Also sorry I forgot to take a picture of the bucket the old coolant was draining into, but this was the coolant that was leftover in the tank. It was like a brownish green color.

So in the end we drained about a gallon of the old coolant and put a gallon and a half in (it leaked so it needed more). My car takes 10.5 quarts which is 2.625 gallons, so there's still a little over a gallon of the old stuff in there. But after running it around with the heat blasting for a while, the coolant in the overflow tank was still a nice blue color just like when we poured it in. It would have been nice to completely flush it, but I'm not sweating it, it's not that big of a deal. Maybe we'll do it next year.

But anyway, everything was a success and the car temperature took a while to get to the middle line, so I say the new antifreeze is working.
 

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He didn't want to flush it out because he was afraid we weren't going to get the right mixture because we didn't know how much water would be in the engine after it flushes.
Umm, if you're going to do coolant changes you need the proper tools including a $100 coolant refractometer to test the concentration. Drain the coolant through the radiator drain, refill with water, drive for 10-15 minutes with the heat on high. Repeat 5-6 times until what comes out is clear water. Repeat once or twice refilling with distilled water. Then refill with coolant to your best approximation of 50%. Drive for 10-15 minutes with the heat on high and let cool overnight. Then test with refractometer. 50% ideal but 40-60% probably fine unless it gets below -20F regularly. If you only have to this every 100,000 miles, might as well do it right.

 
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