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#1
Old 08-24-2008, 01:06 PM
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Is a "radiator flush" a total waste?

I have a 1998 Chevy Cavalier that works quite well. I just had the oil changed and here is what the worker told me.

He showed me a test, which was basically a tube that had floating balls in it. He said, "Look. All six balls are floating and it says 'not safe' on the rating. You might have problems in the winter." He recommended a radiator flush, which costs $39.95.

Should I have done it? What was that test thing with the floating balls?

By the way, I live in Michigan, where it gets cold. I keep my cars in a garage, but it is still quite cold in winter.
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#2
Old 08-24-2008, 01:24 PM
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The little thing with the floating balls is a hydrometer that measures the specific gravity of your coolant.
Anyway, yes coolant does wear out and needs to be changed. How often is a function of what type of coolant is in the system. I think that a '98 Chevy will have Dex-cool in it (Orange in color)
Dex-Cool is supposed to be a 5 year 100,000 mile life, but there are some people that don't believe it.
Anyway with any anti freeze if the anti-corrosion chemical package in the AF wears out, the inside of the engine will corrode. This can cause issues with head gaskets, seals and radiators. I have seen cases where the water passage in a cylinder head was so eaten away from bad antifreeze that the head gasket blew, and the entire cylinder head needed replacement.
#3
Old 08-24-2008, 02:53 PM
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$40 isn't a bad price to pay to have someone do that. The 'floating balls' test is a valid indicator, I just don't remember if balls floating, or balls sinking was bad (it's been a long time since I had a car I needed to worry about.)

If you've never touched the cooling system, and the car is 10 years old, DEFIANTLY perform a flush on it. It just takes one unexpected night out of the garage in your area of the planet to have an EXPENSIVE repair.

Antifreeze does what you think it would...it doesn't freeze. Water freezes at 32 degrees. Anti-freeze makes it do the coolant won't freeze at, shootin' from the hip, 40 below.

When water freezes, it expands. When it does so in you car, it's expen$ive.
#4
Old 08-25-2008, 12:12 PM
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The other option is to look for the petcock at the bottom of the radiator, stick a pan under it, open it, drain the contents of the radiator, close petcock, refill radiator with antifreeze. This won't clean the gunk out of your cooling system, but it will definitely protect your car in the winter.
#5
Old 08-25-2008, 12:20 PM
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One thing to keep in mind is that you should never fill your system with pure antifreeze. Follow the directions on the back of the bottle for proper dilution with water.

There is an interesting colligative phenomenon when ethylene glycol and water are mixed. Certain mixing ratios have a lower freezing point than either pure water or pure ethylene glycol.
#6
Old 08-25-2008, 12:21 PM
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Quote:
Originally Posted by Chefguy
The other option is to look for the petcock at the bottom of the radiator, stick a pan under it, open it, drain the contents of the radiator, close petcock, refill radiator with antifreeze. This won't clean the gunk out of your cooling system, but it will definitely protect your car in the winter.
Mixed with water, of course.
#7
Old 08-25-2008, 12:28 PM
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Just another chiming in to say, no, not a waste, not a scam. Just something that only we owners of old beaters have ever had to deal with. If you're leasing a car or buying a new one every 3-4 years, you won't have to change the antifreeze, but when you're in the 10 year range, yep, you bet.
#8
Old 08-25-2008, 02:59 PM
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Yep, do it. You will likely see your car run a bit cooler afterwards, assuming your temperature gauge isn't a "dummy" one that is either on or off.
#9
Old 08-25-2008, 03:54 PM
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An engine coolant flush is not a waste, it's a very important maintenance procedure. However, it has nothing to do with the floating balls, which are indicating unsafe for a different reason.

Engine coolant should be a 50/50 mix of antifreeze and water for most climates. It can be up to 70% antifreeze for frigid climates. Pure anitfreeze is not good - it doesn't transfer heat as well as water (and that's the coolant's primary job), and it can freeze at a higher temperature than the mixture. The floating balls of the hydrometer correspond to the mixture ratio. Five balls will float with a 50/50 mix; if the sixth ball also floats it indicates too high a proportion of antifreeze (which can easily be corrected by draining out some of the coolant and replacing it with just water). Pure water isn't good either - it freezes too readily, boils too readily, and fosters rapid corrosion.

That corrosion is the reason to do a flush and fill. Antifreeze has anti-corrosion additives which get consumed doing their job. The coolant gets progressively more acidic, and if neglected can cause deterioration of any metal it contacts. Typical recommendations for flush intervals are 2 years/30,000 miles for conventional antifreeze and 5 years/100,000-150,000 for long-life antifreeze (many of us in the field find the long-life interval to be overly optimistic). It's wise to do a flush at least as often as recommended, but even better is to actually measure the pH of the coolant to see if it's at the point where it should be changed.
#10
Old 08-25-2008, 04:20 PM
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Quote:
Originally Posted by Unintentionally Blank
If you've never touched the cooling system, and the car is 10 years old, DEFIANTLY perform a flush on it.

Nothing of value to add, just:

Totally innocent typo; totally hilarious mental image..."I do NOT want to do this!! You're MAKING me do this!! *performs flush* Dammit!! I did NOT want to do that!"

Again, it's just a typo, not nitpicking (I've had more than my share of unintentionally hilarious typos), but I cracked up imagining how someone might perform a flush in utter defiance.
#11
Old 08-25-2008, 04:43 PM
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Quote:
Originally Posted by Cuckoorex
Nothing of value to add, just:

Totally innocent typo; totally hilarious mental image..."I do NOT want to do this!! You're MAKING me do this!! *performs flush* Dammit!! I did NOT want to do that!"

Again, it's just a typo, not nitpicking (I've had more than my share of unintentionally hilarious typos), but I cracked up imagining how someone might perform a flush in utter defiance.
I blame my iPhone....even if I didn't use it to respond to this thread.
#12
Old 09-05-2008, 06:49 AM
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$40 sounds unusually low for a radiator flush. Where I live it seems to cost at least $90, and usually more.

I'm confused about coolant changes and I can't get any straight info. I'd like to possibly change mine myself, but every source I go to has a different method. Some sound easy and others sound difficult. Some just change part of the fluid, while others flush everything out with a garden hose (as opposed to the specialized flush machines they use at shops.) And when I go to shops, some say drain & fill is okay, while others say that you're always supposed to do a flush.
#13
Old 09-05-2008, 07:02 AM
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Quote:
Originally Posted by riker1384 View Post
$40 sounds unusually low for a radiator flush. Where I live it seems to cost at least $90, and usually more.

I'm confused about coolant changes and I can't get any straight info. I'd like to possibly change mine myself, but every source I go to has a different method. Some sound easy and others sound difficult. Some just change part of the fluid, while others flush everything out with a garden hose (as opposed to the specialized flush machines they use at shops.) And when I go to shops, some say drain & fill is okay, while others say that you're always supposed to do a flush.
When you get that much variability, it means the details aren't important.

Just ask a group of 'car guys' about oil changes. You'll hear everything from 'I follow the sticker JiffieLube puts on my windshield' all the way to 'I buy racing oil from Redline and send samples out for analysis...it kept me from buying a new motor when the oil pump started to fail'.

The reality is: If oil changes enter ANYWHERE in your subconscious, you're probably changing it enough to be adequate. It's the folks which is never occurs to that you need to worry about.

Same goes for radiator flushes. The act of changing it out replaces the conditioning package in the coolant that keeps it from eating up the innards of the cooling system. It can also improve cooling performance....if the old fluid was not hacking it. I the fluid wasn't the problem (the radiator, radiator cap, or thermostat) then changing the fluid by itself won't help as it wasn't the underlying problem.
#14
Old 09-05-2008, 07:13 AM
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Quote:
Originally Posted by Unintentionally Blank View Post
When you get that much variability, it means the details aren't important.
The only thing is that they say that air can get trapped in the system, leaving spots that don't get any cooling and thus get dangerously hot. Some procedures have complicated measures to prevent this, and some don't.
#15
Old 09-05-2008, 07:17 AM
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Quote:
Originally Posted by riker1384 View Post
The only thing is that they say that air can get trapped in the system, leaving spots that don't get any cooling and thus get dangerously hot. Some procedures have complicated measures to prevent this, and some don't.
Yes, but I'm assuming from the OP that a professional will be performing the procedure.
#16
Old 09-05-2008, 09:28 AM
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Quote:
Originally Posted by riker1384 View Post
$40 sounds unusually low for a radiator flush. Where I live it seems to cost at least $90, and usually more.

I'm confused about coolant changes and I can't get any straight info. I'd like to possibly change mine myself, but every source I go to has a different method. Some sound easy and others sound difficult. Some just change part of the fluid, while others flush everything out with a garden hose (as opposed to the specialized flush machines they use at shops.) And when I go to shops, some say drain & fill is okay, while others say that you're always supposed to do a flush.
If it's performed often enough, before any corrosion has started, a drain and fill is adequate. The problem is how much can be drained out. On most cars, just draining from the radiator will only get about half of the old stuff out. If there's a block drain that can be opened, that might get about 85% of it. There will still be old coolant in the heater core and a few other areas that don't drain out. In these cases, the next service will need to be proportionately shorter to accomodate the fact that not 100% of the antifreeze in the system is fresh.

I flush with a hose, going through the radiator, the heater core, and the hose to the core. If there's a block drain that's reasonably accessible, I open it. I flush until clear water comes out, and temporarily block some of the openings (heater pipe, heater hose, radiator drain, block drain) so as to force the water flow through the other (unblocked) openings to get a thorough backflush. This gets 95+% of the old stuff out. I then open all drains, install the radiator cap, and use compressed air through the heater and heater hose to get as much residual water out as possible. Then I add the correct amount of pure antifreeze (half of system capacity), and finish filling with water.

On many cars, the possibility of having an air pocket is a significant concern. Sometimes this can be dealt with by following proper bleeding procedures (which tend to be a pain in the neck). I use a tool run by compressed air that draws a vacuum on the system to eliminate air pockets, but the average do-it-yourselfer wouldn't find this feasible - $100+ tool and compressed air for an occasional job.

I've never used a flushing machine. It seems to me you'd have to use a fair amount of fresh coolant to ensure getting all the old stuff out, given the network of areas involved (radiator, engine, heater, etc.). I have seen a case where a shop used such a machine and left a huge air pocket in the system - it still takes someone who knows what they're doing to get it right, machine or not.

If the change is overdue and corrosion has started, a flush is definitely called for. I've seen cases where a double flush was necessary - one with a cleaning chemical, then one with water. Better to do a half-assed flush early than to let it go that long.

So the issue of whether this is something you could/should do yourself depends on what condition your coolant is in, how hard or easy it is to drain your car's system, and how hard or easy it is to get all the air out.

I agree that 40 sounds way low. My fees range from 75-125 depending on the vehicles system capacity, design (rear heater?), and type of antifreeze called for. I'm tempted to think it's poor pricing strategy (selling it too cheap) rather than doing a poor job, but who knows? It's a pretty safe bet, though, that it is using conventional (green) antifreeze in every car rather than the type the manufacturer calls for.
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