Volvo penta 4.3GL over heating.

Hello all.
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I have a 2005 volvo penta with sx out drive. I notice 2 weeks ago that everytime I ran the RPM to 3000 the overheat alarm will sound but when I lower the RPM then it will be fine. Couple of days ago I have a mechanic change the imppeler and notice that the old imppeler missing some pieces but he did not try to look for them and I did not know that what he supposes to do. I took the boat out couple of days ago and it over heat right after I left the dock. Called the mechanic down to the dock and he took of the imppeler housing, the T-stat housing and found some missing pieces from the old imppeler. put everything back together and started the engine and it start to overheat at idle after about 5 minutes.*Took of the risers yesterday and did not find any thing that could have obstruct the flow and according to the mechanic the risers looks OK. Hook up the hose to engine flush and flush out the engine for about 45 minutes and engine was not over heating. hook up the earmuff to the out drive and no water suck in at all and engine over heat after about couple of minutes but if I hold the earmuff on both sides and squeeze them then engine start to suck in water and exited out though the exaust like it suppose too but if I let my hand go the engine will not suck in any water. Any susggestion will greatly appreciated.

Hello every body.
I have a 2005 seaswirl striper with a 4.3gl volvo penta I/O. Just last week it started to overheating when I go over 3000 RPM. Called a mechanic and he replaced the imppeler but did not get all the broken pieces out. went out the next day and it over heat right away, came back to the dock and called the mechanic again and he came down to the dock and took off the t-stat housing, the raw water pump, the heat risers and check all the hises. Did managed to get most of the broken imppeler pieces out. test the engine and still overheating. Hook up the hose to the engine flush and it look like no flow restriction but still can not get any water to suck in to the engine when using the earmuff. I'm new to boat and this is the first time having problem. PLease help and thank you very much.

Sounds like some missing impeller pieces are stuck somewhere.

My volvo drive has a hole on the bottom and I can't use ear muffs because it sucks in air and not the water. I made a hose contraption that I hook up to the raw water intake of my water pump when I want to run it in my drive way.