I shredded my first impeller on the Universal M-18 with an Oberdofer raw water pump. What a pain to fish out all the little bits of impeller from the exit port and hose!
Silver lining - I found this source for replacement impellers at a reasonable price:
https://www.ebay.com/itm/Impeller-K...eAAAOSwcj5ZTr~Z:sc:USPSFirstClass!76210!US!-1
They have an assortment for other engines and pump models too if you don't have the M-18/Oberdorfer.
KBG
Silver lining - I found this source for replacement impellers at a reasonable price:
https://www.ebay.com/itm/Impeller-K...eAAAOSwcj5ZTr~Z:sc:USPSFirstClass!76210!US!-1
They have an assortment for other engines and pump models too if you don't have the M-18/Oberdorfer.
KBG