From what I understand the impellers can crack very quickly if there is any restriction in waterflow; even if it doesn't result in engine overheating
. I replaced the impleller on my 44a and after 40 hrs of running, I checked the impeller after noticing reduced waterflow in the exhaust
. One of the vanes had already broken off and another was cracked. I then found another three broken vanes jammed in the pump outlet restricting flow. I suggest you check the raw water cooling
circuit including heat exchanger
for broken vanes or bits of zinc from the sacrificial anode.
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