Moderate rust in older block coolant jackets?

[LM]

Even with regular coolant changes, is it normalish for an older (+15 yrs) iron block to have some moderate rust & scale inside the cooling channels?

I thought it better to post here, vs Cooling System Fluids & Additives, as thought there'd be some head gasket replacement and/or engine rebuilding folks here...

 

[Chris142]

Some engines are worse than others. The worst ones I see are 60's 289 Fords and 97 and newer 5.2/5.9 Dodges. We sell an inline filter to keep the stuff from plugging the radiator.

 

[ikeepmychevytoo]

Hard water causes scale. Scale may cause rust.

 

[LM]

Thanks. This is in regards to a guaranteed/hot-tested 85K mi salvaged engine (91 Saab 900 4 cyl turbo).

One of the core/freeze plugs was rusted from the inside out - the plug has been tossed so I couldn't inspect (I don't think intentionally) - yet the shop proceeded with replacing seals (per initial request), and mating the underbelly (rebuilt) trans. There's moderate debris on the block, from the rusted plug, which I'm going to reinspect. And possibly pull/inspect/reinstall the two remaining plugs.

The shop replaced a couple of the freeze plugs last. The engine & trans have not been installed into the car yet. It would have made a lot more sense to me to have inspected the engine first, made a phone call to exchange, before the labor was done... (the shop didn't think it was a big deal, and may be it's not)

I don't know the extent of the rust, but it seems it would increase the probability of early head gasket and water pump failure. Borescope anyone ;-)?, but I really don't have the experience or reference comparison for for an informed evaluation.