cooling system flush

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  #1  
Old 07-01-12, 09:19 AM
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cooling system flush

I'm planning on "back flushing" my cooling system using one of those Prestone flush n fill kits where a T is installed onto the heater inlet hose to which a garden hose is then attached and the system is flushed out through the top of the radiator, the method described here: How to Backflush a Vehicle's Coolant System | DoItYourself.com
My question is in regard to the opening of the thermostat if this method is followed. If cold water is continually running through the garden hose into the system while the engine is running, won't the thermostat stay closed and prevent full circulation through the whole system? I've probably got a misunderstanding of the coolant flow and how this works exactly, so perhaps somebody could comment/explain to help un-confuse me about this? thanks
 
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  #2  
Old 07-01-12, 05:03 PM
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The water pump pumps water past the thermo and dumps it into the rad. With the thermo closed theoreticly the fluid would have to go in the other side/bottom of the rad and do the most good. I am not a big fan of this type flushing,but at least you will get the coolant changed.
 
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Old 07-01-12, 05:29 PM
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Didn't instructions tell you to pull t-stat out? You also must have system on full heat, to flush heater core same time.
 
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Old 07-01-12, 08:33 PM
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The instructions do not mention pulling the t-stat out. I went ahead today and did it, following the instructioins, which include having the heater on full during the flushing procedure.
Retired wrench, may I ask why you are not a big fan of this type of flushing? I can't say I'm a particularly big fan of it either. Feel like sure maybe I got the coolant changed but somehow don't feel like it did that thorough of a flush job. Not sure why, but just seems like it.
 
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Old 07-01-12, 09:11 PM
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Because this type flush will not remove rust sediment that is settled in the block and other low places. If you took the thermo out you probably didnt get any flow thru the block. If you ever saw a water and air backflush you could realise the difference.
 
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Old 07-02-12, 07:49 AM
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I see. Well I didn't take the thermo out. Instructions didn't say to, and as mentioned I just followed the instructions. Maybe the wording "I did it" in my previous post here indicated I took the t-stat out, but no that's not what I meant.
Can't say that I've ever seen or heard of a water and air backflush. I'll google it.
Thanks.
 
  #7  
Old 07-02-12, 03:43 PM
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It is a gun that you stick in a rad hose and clamp it. It has a fitting for a garden hose and an air hose. You turn on the water till the system fills then turn on the air and watch the rust fly.DO NOT hook this up to the heater core,,,dont ask.
 
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Old 07-04-12, 10:30 AM
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Unless I missed it you didn't say make, model, age, and mileage of this vehicle. Was there obvious rust or discolor under the radiator cap or in the overflow tank? Or is it just on schedule for antifreeze replacement?
 
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Old 07-04-12, 10:49 AM
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grandspan,
No you didnt miss it, I never mentiioned the make, model, age, and mileage, which is Ford, Ranger, 1998, and 97,000 miles. No rust or discolor under radiator cap or in overflow tank. Fluid was still green and didnt look obviously bad, and with tester said still had adequate freeze/boil protection. Was way past due for antifreeze replacement, according to recommended maintenance. Last actual cooling system flush was done at 69,375 miles in 2004 according to the records I kept. Likely the anti-corrosive and lubricant properties of the old antifreeze/coolant was diminished or non-existent anymore, (I think thats the main reason you're supposed to change it every three years or so) although upon general glance inspection into the radiator I didn't see anything in the way of corrosion or anything else unusual. Hadn't experienced any cooling system problems with it, so am just figuring glad I got it changed out and flushed for now and that it'll be fine but to not to wait so long before the next change out/ flush.
 
  #10  
Old 07-04-12, 10:29 PM
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I typically just do a "drain" and refill every 2-3 years with 5 year 60,000 mile coolant for my cars. It's worked well for me (knock on wood). I fill up old anti freeze jugs with the old coolant and they almost come out to what the total capacity for my car is every time. 180K on one care and 110K on the other and no cooling issues (knock on wood). Pretty simple thing, no need to do all the flushing, etc. If I had a car that didn't have cooling service done regularly I'd probably take it somewhere for the $80 "power flush" once and then use my method after. Just food for thought.
 
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Old 07-04-12, 10:43 PM
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butchyboy,
So to drain the whole system (not just the radiator), what method to you use to get all the coolant out of the engine block? thanks for input
 
  #12  
Old 07-04-12, 10:56 PM
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On my older Honda there's a bolt on the back of the engine you pull that drains most from the block after draining from the radiator. It typically involves an antifreeze shower and, since I'm not keen on drinking antifreeze or getting it in my eyes, sometimes I skip that part and instead drain the radiator, put water in (NOT TAP WATER!!!), run the car, drain the radiator, add more water, run the car, etc. This get the antifreeze out of the radiator, lets the water mix with the rest of antifreeze in the block and moves it through the system for the next drain. After a couple of these cycles I figure MOST of the old is out and time for new. I keep tabs on how much water I've put in and how much I've drained, and know the total capacity, so I can guesstimate how much water I need to add in the end to get approximately 50/50. Kind of a hassle but less annoying than those flush kits (in my opinion) and less disgusting than getting bathed in coolant. My other Honda doesn't mention draining the block. Just draining the radiator. And, doing that, I get almost exactly the full capacity so I figure there isn't enough old left to do much.
 
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Old 07-04-12, 10:59 PM
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Ok. I see. Good food for thought for my next change. thanks!
 
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Old 02-01-14, 01:15 PM
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My understanding is that they are attempting to perform a reverse flush. Using the little backflow preventer and leaving the thermostat in forces the water to go in opposite direction through the heater core then through block to water pump and supposedly through opposite direction in radiator.

I have one problem with this theory as many cars, especially Nissans, the thermostat is in the bottom hose.

Once the water gets to the water pump and the thermostat is closed the water will be forced to go into the radiator through the bottom hose. Is this the normal direction for coolant is returning through top hose normal?

If returning through top hose is normal, then radiator will also be getting back flushed due to water being forced through bottom hose and up through radiator.

I've got figure out how to properly back flush a Nissan with thermostat in bottom hose. May, just give up on back flushing and just flush normally and be done with it!

Good luck everyone!
 
  #15  
Old 02-08-14, 06:21 PM
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I am sure I will get flamed , but here goes .

On my personal vehicle , I never flush the cooling system , never drain it . But the key is I never put water in it . 100% antifreeze only . No water , no rust .

I know it is said 50 - 50 water and antifreeze cools better than 100% antifreeze . But 100% antifreeze cools much better than a cooling system that is 1/2 clogged with rust & crud . And yes , our summer temps exceed 100 F . And winter temps rarely get colder than 0 F .

Plus , if I have an emergency repair ( replace a hose ? ) , and have to add some water , I still have enough antifreeze in the system to work OK , untill I get home .

God bless
Wyr
 
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