MerCruiser Impeller Meltdown

[Ski Sanger]

I have a MerCruiser Black Scorpion engine (330hp) in a V-drive ski boat. After 50 hours the water pump impeller melted down. There was never a cause or a reason found for this. Now at 200 hours the motor has overheated again. Since the first incident I always keep my eye on the temp. gauge and this time the motor ran hot for maybe 30 sec. before I shut it down. Each time this has happened has been just after launching the boat. By the time I idle through the launch area/no wake zone it over heats. The boat has NEVER been started dry or brought close enough to the shore to suck up debris. Why is this turning into a chronic problem? Is it the thermostat? What should I be looking for when I take the pump apart? Is it possible to idle too slow through a no wake zone for a prolonged period and not get enough water flow ?

 

[orca]

Re: MerCruiser Impeller Meltdown

G,day. 50 hrs is too low for an impeller. has the pump housing ever been replaced. the pump housing is plastic and if it has ever been hot may have distorted. I am assuming that the pump is a genuine mercruiser pump. Merc produce a kit that includes housing, impeller, gaskets and wear plate.

 

[Ski Sanger]

Re: MerCruiser Impeller Meltdown

After the first melt down they replaced the entire pump; impeller, body and all. I remember it taking a while to get the new pump because Mercruiser had just redesigned the pump and I got the new model. Reguardless here I am needing a new pump again.

 

[Bob_VT]

Re: MerCruiser Impeller Meltdown

At an idle your pump should still be working just fine. I would inspect the lines for blockages and check the rest of the motor out too.<br /><br />Most pump meltdowns occurr when a pump is run dry out of the water. I would sincerely question the quality of the work that was done previously. Did it carry a warrenty?<br /><br />Bob