Join Date: May 2007
Location: Glen Cove, NY
Thanked 88 Times in 82 Posts
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Re: water flow GPM per HP of an engine?
Your guess of 3-5 GPM is probably pretty close. However since his engine is an older raw water cooled engine, I would suspect scaling or clogging of the cooling passages is more likely the cause. An oxalic acid flush may help. When I changed the head gasket on the Universal 5411 on my previous boat, I found 5 of the 8 engine passages completely plugged. Flushing had not been able to open them.