Get some litmus paper and check the ph. Thats a great way to understand the worst harm the fluid could pose.

I ran a coolant filter a while back when my 617 had some terrible rust issues. After 3k miles, I cut open the filter to find about a hefty tablespoon of sand and finer material.

The worst that could do is erode the water pump... which has pretty beefy vanes and such a small quantity would have to pass by for quite some time to amount to any damage.

Look in the top of the radiator for larger debris. If you suspect larger pieces, they may be an issue in the water jackets in the block.

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