Engine Coolant Change

[Joe L.]

There was a recent topic on this board that asked about oil change interval and "morphed" into a discussion about coolant change intervals. So, I'll start a new one here about coolant.

One of the problems with a coolant change is that to do the job right, one really needs to open the block drains. This can be a real PIA on many cars, new and old. They're either seized tight, require the removal of the knock sensors (LT1, LT4), or are just difficult to access.

Many years ago, I used to use a Prestone Flush-And-Fill kit. This kit requires the addition of a supplied "T" to one of the heater hoses. The "T" can be capped afterwards or the heater hose can just be replaced (coolant change time might not be a bad time to replace heater hose, anyway---it's cheap enough even if you use reproduction hose).

When I used to use this kit it worked great. After flushing the system, you simply let the radiator drain, close the drain cock, and add the correct amount of full strength coolant to get you to the % you want (I usually use 55-60%). Last, you top off with water. Done. It makes coolant change a very easy job.

These kits are still available, but I have not used one in awhile. Has anyone else here used one lately, especially on a later model car, Corvette or otherwise?

[Rob F.]

Re: Engine Coolant Change

Great information about how to change the coolant but how frequently should you engage in the process of changing your coolant on a classic car that isn't driven like a daily driver or is driven somewhere in between.

[Terry M.]

Re: Engine Coolant Change

Joe,
I haven't installed one of those T fittings in the heater hose lately, but I have one in the Corvette -- in the hose that replaced the one that sprung a leak a decade or so ago. Seems to work fine.

I will repost my links from the earlier thread since some one may look this up in the future:

Since this thread has migrated from oil to coolant -- check out this idea. I am not sure if this works better with aluminum or copper/brass radiator -- or even if that makes a difference.

http://www.ehow.com/how_4564140_chec...lti-meter.html

Here is a link for those more visually inclined:

http://www.youtube.com/watch?v=mBXZtfzHhig

[William G.]

Re: Engine Coolant Change

Joe,

Yes.........that will work but you end up with a "ton" of anti freeze to dispose. It is toxic (at least the type we use in our "old" cars) and it shouldn't be disposed of down the sanitary drain and the storm drain is just as bad. So we're back to trying to open those d*** plugs on the block--that way you only need dispose of a limited amount of anti freeze/water. As I understand your way either you capture an awfully lot of coolant to dispose of or you just "let 'er go" (diluted, to be sure, but that doesn't alter the fact that it is toxic).

To me at least this anti freeze issue is a conundrum!

Bill

[Donald O.]

Re: Engine Coolant Change

While I have used the old school Prestone flush system on several other cars, I have heard that using it with the aluminum radiators will shorten their life. Has anyone else heard or know the facts about this?
Don

[Joe L.]

Re: Engine Coolant Change

While I have used the old school Prestone flush system on several other cars, I have heard that using it with the aluminum radiators will shorten their life. Has anyone else heard or know the facts about this?
Don

Don------


I think you're referring to the Prestone Coolant System Flush CHEMICAL. I don't use that. The Prestone Flush-And-Fill kit does not necessarily use or require any chemical. The chemical flush is a separate operation if one chooses to use it. The Flush-And-Fill kit simply uses water from a garden hose to flush the system. One flushes until the water come out clear. Then, drain all the water possible, add the correct amount of full strength coolant to get you to your desired % (e.g. if you have a 20 quart system and you want 50% coolant, add 10 quarts of full strength coolant), and top off with water.

[Kevin G.]

Re: Engine Coolant Change

There is a "tee" fitting on my LT-1, which did cost me a point or two during judging . Very hard to see as it's located just under the AC comp. the judge (GB) had a good eye!

[Joe L.]

Re: Engine Coolant Change

Joe,

Yes.........that will work but you end up with a "ton" of anti freeze to dispose. It is toxic (at least the type we use in our "old" cars) and it shouldn't be disposed of down the sanitary drain and the storm drain is just as bad. So we're back to trying to open those d*** plugs on the block--that way you only need dispose of a limited amount of anti freeze/water. As I understand your way either you capture an awfully lot of coolant to dispose of or you just "let 'er go" (diluted, to be sure, but that doesn't alter the fact that it is toxic).

To me at least this anti freeze issue is a conundrum!

Bill

Bill------


My work for my entire 33 year career involved environmental regulation specifically relating to water. I can tell you this: concentrated, drained (spent) coolant should never be disposed of to the sanitary sewer system or the stormwater collection system.

Dilute coolant (such as that created with a flush-and-fill kit) should never be discharged to a stormwater collection system or other natural outlet (e.g. creek, stream, etc.). However, I consider that dilute coolant can be safely and legally discharged to a sanitary sewer system. Ethylene glycol, in the dilute form and especially as further diluted in the sanitary sewer system is VERY biodegradable (biological treatment is the general process used in the vast majority of municipal wastewater treatment systems). I know of no specific regulations prohibiting the discharge of ethylene glycol to a sanitary sewer system or, even, limiting the concentration at which it can be discharged. Some agencies might "hang their hat" on the general prohibition of discharging toxic substances but, carried to the extreme, that would also mean you couldn't use bleach for your laundry.

The main problem with spent coolant is the concentration of certain heavy metals which may be present. These are leeched out of various automotive cooling system components via natural and inevitable corrosion of those components. However, we (and other agencies) did an extensive study of the concentrations in coolant of various heavy metals for which specific discharge concentration limits were adopted. We found that even in concentrated spent coolant the limits for all of the regulated metals were barely exceeded. In the dilute coolant, the concentrations were well below the allowable discharge limit. In systems with primarily aluminum metallic components (as is the case with most modern system), the concentrations of heavy metals in even the concentrated coolant is well below discharge limits.

So, if one drains as much as possible of the concentrated coolant from the radiator/cooling system and disposes of it to a hazardous waste collection facility, the dilute coolant in the flush should be fine for disposal to the sanitary sewer system.

[Jim T.]

Re: Engine Coolant Change

I use the sanitary drain, kitchen sink to dispose of drained coolant.

[Jake D.]

Re: Engine Coolant Change

I take it over to my local Chevy dealer. They have tanks there for drain oil disposal, and Anti freeze disposal. I have been recycling both for 30 years!

[John F.]

Re: Engine Coolant Change

Great reading. I guess all those oil changes, anti freeze flushes, and taking out the ashes from the coal furnace never hurt a thing in the alley behind my mom's house. The grass is greener than ever before now. That was over 40 years ago.

[Richard D.]

Re: Engine Coolant Change

Don------


I think you're referring to the Prestone Coolant System Flush CHEMICAL. I don't use that. The Prestone Flush-And-Fill kit does not necessarily use or require any chemical. The chemical flush is a separate operation if one chooses to use it. The Flush-And-Fill kit simply uses water from a garden hose to flush the system. One flushes until the water come out clear. Then, drain all the water possible, add the correct amount of full strength coolant to get you to your desired % (e.g. if you have a 20 quart system and you want 50% coolant, add 10 quarts of full strength coolant), and top off with water.

Joe, it seems that you use regular tap water then with your coolant changes. Many seem to recommend distilled water. Is that necessary with the newer type coolants available? Thanks, Rich

[Joe L.]

Re: Engine Coolant Change

Joe, it seems that you use regular tap water then with your coolant changes. Many seem to recommend distilled water. Is that necessary with the newer type coolants available? Thanks, Rich

Rich-----

It so happens that our tap water here is VERY high quality. Extremely low total dissolved solids (TDS). So, I would gain very little, if anything, by using distilled water.

For the most part, I think plain tap water is fine with most modern coolants. In fact, the aluminum radiator from my 1969 worked just fine for 40 years with regular changes of Prestone and tap water. It's still in fine shape even though I've temporarily retired it.

If you live in an area with high TDS in the tap water, you might be advised to use distilled water. But, if you live in an area with very high quality tap water, I don't think it's needed. Anyone who lives in the San Francisco Bay area and gets water from Hetch Hetchy (SF Water) or Pardee Reservoir (EBMUD) will achieve practically nothing using distilled water.

[Jack H.]

Re: Engine Coolant Change

So what is the answer to what the coolant change interval should be on a car that isn't driven much? Probably been 5 years for me but no more than 2000 miles.

[Terry M.]

Re: Engine Coolant Change

Depends on what you have for coolant:

Green = every 2 years = convnetional EG
Orange = every 3 or 4 years = DexCool
Yellow = every 5 years = HOAT or G05

This is my opinion. Others may be different. Of course sooner is always better, and a test with a strip or the DVOM might indicate a sooner or later change.