The Supercar Registry - Flushing a engine block that has been sitting.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 69PACE</div><div class="ubbcode-body">I've never done this myself, but an old farm trick is to use straight white vinegar to dissolve blockage. You will have to drain, flush then fill, but if the plug is organic mater it will eat its way through in a couple of days. I've used it on drains and the pipes are fine.

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This is what my dad does, he just did a 41 Plymouth Woodie Wagon that had been sitting for 30 years the system was so chunked up and nasty the car would hardly circulate water, cools great now.