2000 Chaparral 5.7L EFI Bravo III cooling - thermostat housing outlet question

Several of my impeller blades broke into pieces and I was able to account for almost all of them. My concern is that there are additional pieces stuck in the thermostat housing. While driving on the lake, the engine runs at 180 degrees (I put in a new 160 degree thermostat.) I found 3 pieces of impeller lodged in the thermostat housing and removed them. I have checked the hoses up to the thermostat housing.

I believe this is causing vapor lock, because after the engine is hot and I turn the engine off, I can crank it if it is off for about 10 minutes. If I sit for about an hour, the engine does not crank until the next day. It keeps grinding, but will not fire.

The seawater pump hose feeds cool water into the thermostat housing, and there are 3 additional hoses on the housing. Two hoses go to the exhaust manifold and the other hose goes to the circulating pump. Should all of these hoses be cool to the touch when the engine is hot? Currently, the hose from the seawater pump is cool and the hose on the same side of the thermostat housing that goes to one side of the exhaust is cool, but both the hose going to the other exhaust manifold and the hose going to the circulating pump are hot.

Are there any other common spots to find impeller pieces? Also, is there some type of filter available to put inline just after the seawater pump to avoid this major design flaw? I will also be changing the impeller each season. Thanks in advance for any help.

Re: 2000 Chaparral 5.7L EFI Bravo III cooling - thermostat housing outlet question

Changing the impeller every season is a waste of time and money. Unless you regularly run aground in gravel. It's not a design flaw, it's a catastrophic failure due to abuse or a lack of maintenance that causes impellers to come apart.

The other common place for impeller pieces to get stuck are in the fuel cooler and the power steering cooler. Removing the inlet hose from the thermostat housing and backflushing with a good pressure garden hose is the best way to get all the pieces out.

Re: 2000 Chaparral 5.7L EFI Bravo III cooling - thermostat housing outlet question

When you find an impeller in that condition it is most imperative you find EVERY piece. We piece them together like a jigsaw puzzle to make sure.
first place is the PS fluid/inlet water heat exchanger. Follow the water hose from the rear and usually lower part of motor block inline with the water hose. Pull the hoses (yes both) off and flush from bow to stern direction. May have to remove and "rod out" some pieces.

Re: 2000 Chaparral 5.7L EFI Bravo III cooling - thermostat housing outlet question

Thanks for the replies and I will go back through the cooling system. A big concern was that there were pieced lodged in the thermostat housing that were difficult to access and get out. Can anyone confirm if the 3 outlet hoses from the thermostat housing (2 to the exhaust and 1 to circulating pump should be cool to the touch while the engine is hot?