Here's the story:

Original 2 row radiator sprung a leak where the core attaches to the upper tank, so I bought a 3 row unit from MSA, as well as a new water pump(for good measure), 160 degree thermostat, and some new radiator hoses.

The inside of the block and head have a lot of hard deposits in the water passages. I am thinking these are just deposits from using crappy water/coolant in the past since they look like calcium deposits that you sometimes find in old water pipes.

Now to my question:

How can I clear out some or most of these deposits? There isn't a radiator or water pump on the car right now, but the old water pump seemed to have blades in perfect condition(so maybe i'll use this for the flushing before swapping). If I put everything back together with the new(non-leaking) radiator, and get one of these chemicals you run in the system for an amount of time, would it likely cause a build up in the radiator?

What kind of flushing agent would you guys recommend?

The amount of buildup seems like it might be affecting the heat conduction into the coolant. Just flushing with water didnt really do anything to these deposits

Years ago when I lived in Iowa and Michigan and I did my own Anti-Freeze changing, you could buy a solution to flush out your cooling system.

I don't recall the brand or the name, but it came in a miniature version of the anti-freeze jug. The instructions were to pull out some water / antifreeze from the radiator (about 16 oz.) and fill with the contents of the bottle. Then you ran the engine up to operating temperature and about 10-15 minutes after. Afterwards you would just drain the system, refill with plain water, run for a few more minutes and drain again. I don't believe you were required to drain before you added the flush liquid.

Then you would add your new anti-freeze / water mix.

The product claimed to eliminate hard water deposits as well as buildup of any corrosion within the system. It did advise that it COULD open up holes in gasketing that had been sealed by the prior deposit / scale. It did not specify that you had to remove any of the parts you are mentioning.

I've long since relegated that type of activity to my mechanic, so I cannot say whether or not you can still find it in an auto supply store.

Hope this helps.

Enrique

you could buy Prestone flush fluid in a miniature bottle as you described. I used to use this in my 73 in the early 80s and it was very simple. I never see that in stores anymore so i'm not sure if they still manufacture it.