On a thread a member stated; I've heard you shouldn't reverse flush the C3 as it can damage the heater core. Anyone else heard this, please chime in.

 

Well, you shouldn't apply house-line pressure to the system or it could just open up an old, brittle heater core. But, if you dial the pressure down or limit the flow to a reasonable level, it shouldn't be a problem. The 'safer' way to do it would be to remove the two hoses from the heater fittings and connect them with a jumper pipe, then do the flush of the block and radiator. You can run some water through the heater while it is disconnected to be sure it is cleared out.

An easier approach is to use radiator/cooling system cleaner [instead of 'flush'] to dissolve the crud while it is in the cooling system/radiator/block. Buy the cleaner on the same shelf with radiator 'flush'. Follow directions and it will get rid of all the crud in the system and scale on the radiator and heater cores {you don't need to disconnect the heater to use this stuff, as the engine provides the coolant flow via normal engine operation}.

 

Thanks for the advice 7T1, the cleaner you mentioned is there any issue using this with an aluminum radiator?

 

You should read the back of the cleaner bottle to make sure before you buy...but I don't recall there being any disclaimer about 'not using it with aluminum components'. It gets diluted with [clean] water you put in the coolant system, so it's not full strength when it's working. I doubt that it will do any harm to it.

 

What's the difference between 'flush' and 'cleaner'? I bought a couple of bottles of 'flush' allready and planned to do this when the weather gets warmer. Is it worth waiting and getting the 'cleaner'? Thanks.

 

It's mostly a lot of marketing hype.
Here are the ingrediants for Prestone and the Gunk brand

Prestone Super Radiator Cleaner
From Prestone literature-
“Non- acidic Prestone Super Radiator Cleaner is easy to use. This formula removes heavy rust and scale deposits. “

Instructions-
Drive a total of 3 to 6 hours (normal driving) - may be intermittent and over a period of several days

Non-Hazardous Components >1%
Water 60-90%
Sodium Citrate 7-13%


Prestone Super Flush
Instructions-
Run engine with heater on highest temperature setting for 10 minutes after reaching normal operating temperature.

Water 60-90%
Sodium Citrate 7-13%
Sodium Xylene Sulfanate 1-5%


Prestone Cooling System 10 Minute Flush

Sodium Citrate 5-10%


Gunk
SUPER HEAVY DUTY RADIATOR CLEANER
2-Butoxyethanol 1.0 - 5.0%
Citric acid 10.0 - 30.0%
Dodecylbenzenesulfonic acid 1.0 - 5.0%
EDTA 13.0%
N-Methyl-2-pyrrolidone 1.0 - 5.0%
Potassium hydroxide 1.0 - 5.0%



Gunk
SUPER RADIATOR FLUSH
2-Butoxyethanol 1.0 - 5.0%
Citric acid 10.0 - 30.0%
Dodecylbenzenesulfonic acid 1.0 - 5.0%
EDTA 7.0 - 13.0%
N-Methyl-2-pyrrolidone 1.0 - 5.0%
Potassium hydroxide 1.0 - 5.0%


As you can see both companies use citric acid as the main ingredient.
The only difference with Prestone cleaner and flush is the length of time they recommend and the additional chemical helps keep particals in solution.

The amazing part is that Prestone advertises their cleaner to be non-acidic and as you can see that is

Here is a link to the stuff I have used for years. Look at the pic of the block drain hole. If you can get the inside of the block that clean, you're ok.
http://forums.corvetteforum.com/c3-t...ner-flush.html

BTW, no matter which stuff you use, flush with the washing soda to neutralize the acids

 

The procedure Prestone recommends with their cleaner [as I remember it] is much different than that shown in prior post. The radiator gets drained and water plus cleaner used to fill the system. There are several days of vehicle operation with the cleaner in the system. Then drain, put clear water back in (this is to flush the cleaner out of the system) and run it some more. Drain and refill with 50/50 mix of water and coolant.

If you have a limed-up radiator, it will clean it up and make a world of difference in the capability of your existing cooling system.

 

Thanks noonie. I've got 3 cars to do this Spring and want to do it right. It would be very expensive if I screw it up.

 

Most systems run 13-15psi caps so whether it's safe to flush with a garden hose depends on what your home water pressure is.

You should also be aware that sometimes things are best left alone. If you don't know the history of the engine you could make problems for yourself.

Years ago my brother flushed his 318 Mopar (high mileage, unknown history) with a cooling system additive, afterwards it started pinking. When I stripped it, the water jackets around the rear cylinders on both banks were completely choked with dislodged, flaky rust

 

Here is the link for their products. Click on instructions for each.

http://www.prestone.com/products/coo...Treatments.php

Here is a link to a simple list of their ingrediants, sometimes we already have the major ingrediants without buying a special product.

http://www.prestone.com/pdf/IngredientStatements.pdf

 

The "instructions" on the site you linked just gives the first step in the procedure shown on the bottle. Websites don't always give the details; this one sure doesn't.

As always, advice has been given by several parties....the Poster can decide what he/she wants to do.

 

Is that topic closed then?

 

That's a good example of why you should do a very good job of it if you decide to tackle it at all.

Most cleaners and flushes are designed to dissolve the scale and rust into small particles, suspend it in solution and carry it out when drained. If a system is severely scaled and corroded, then the scale and mostly rust is just loosened and not drained completely. The first thing that will happen is that these particles will plug up a radiator (especially a new tech small tube aluminum ones) and the heater core.

Done right, it takes me a full day easily, with hundreds and hundreds of gallon of water and you will end up with your driveway srained.
It's an absolute must to use the block drains.

When I bought it



A 5 gallon bucket, still coming out after several hours of flushing



Comparison of the size of the particles



When finished, can't be any cleaner.



Both the 77 and 75 were like this and that's why this is about the first thing I do when I get a car.

You can't beat the results even down here in S Florida where it is always really hot.
The 77 has a chin spoiler, old brass radiator, NO foam anywhere around the rad and runs at tsat temp all the time 195°
The 75 has NO chin spoiler, NO foam, Stewart stage 2 pump, and old brass radiator. Runs at a little less than tstat temp under all conditions. Will probably downgrade to a good stock GM pump since it runs a little too cold.

 

There is a little "next" tab that you have to click on, I missed it too the first time.

 

An funny litlle anecdote to this.

My wife was looking up the reason why our daughter's blonde hair turned green after going in the spa yesterday. The reason was low ph and the copper heater piping etc.
The cure was to use a special shampoo that contained EDTA (Ethylene Diamine Tetra Acetic Acid, the same stuff that is in Gunk's SUPER HEAVY DUTY RADIATOR CLEANER at 13%.

 

Well....there ya' go! If it's good enough for Clairol,......

 

Case closed, I have all the information I need, now I need to "just do it". Thanks for all the input, I plan to connect the heater hose (by pass heater core) flush with super flush, try to open block plugs. My biggest concern is where can I dispose the dirty AF in Mass ( I mean legally).

 

the old 'good stuff' 2-part dry prestone heavy duty CLEANER p/n AS100 was granular oxalic acid (9 oz) ... its granular alkaline neutralizer (2 oz) was sodium carbonate Na2CO3 aka washing soda (Not baking soda) ... as100 No longer available. But granular oxalic acid is available as 'wood bleach' at hardware store ... DAP brand is but one. A&H super washing soda is a neutralizer. Do a search here for mixing instructions also key word GM p/n 12346500 ... several old threads.

http://www.dap.com/product_details.a...55&SubcatID=24

http://www.armandhammer.com/fabric-c...t-booster.aspx

 

EDTA also widely used as preservative ... many blood draw tubes (med lab) contain a bit of EDTA.