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Metal flakes on block port side drain


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Hey guys, I recently got a 99 sportster with the 5.7 carb. engine. I was draining the water for winter and the plug on the port side of the block had a lot of metal flakes attached to it. Does the indmar 5.7 310hp engine have an internal water pump as well or is that just passageway deterioration? I have had issues with cooling this first year with the boat but I attributed it to a bad gauge or sensor. The raw water pump and impeller were replaced in the spring. Thoughts?

Edited by aaronbrooks
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There is an external belt-driven circulating water pump in addition to the raw water pump if that's what you're asking.

I get rust flakes when I drain the block - more when I first bought the boat I think because it wasn't used regularly before. It's not as bad now.

If you're getting cooling issues did you check the transmission cooler for debris or old impeller shreds? Mine was nearly totally stopped up with a shredded impeller from the previous owner.

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  • 2 weeks later...

I also have a '99 Sportster for a year now and the previous owner used petcocks for the block drains so I replaced those with brass plugs last year then I winterized (a week after I bought it). When I winterized this year I used a wire in the holes as they drained and was blown away with how many flakes came out. I will definitely drain the block after running it a time or two this season to see if more comes out. I am chalking it up to the boat being used somewhat regularly this season after spending so much time sitting and hoping that's all it is. 

I pull the raw water pump impeller every winter, install a new one in the spring and keep the old one as a spare in a baggie under the seat. 

There is an engine water pump that can go bad but it Might be a good idea to replace your thermostat before changing that pump. Should be able to troubleshoot the temp sensor and gauge too if you think they aren't working properly.  

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