Possible Impeller Piece Blockage

wyrman

wyrman

Well-Known Member
Jul 12, 2012
1,921
Tri-Cities, Wa
Boat Info
2007 310 Sundancer
Engines
Twin 350's, V drives
2003 Fisher 17 aluminum
90hp Honda 4 stroke
Last summer the starboard impeller fell apart. I got most pieces out, including in the oil cooler.(or is it the power steering cooler)
That engine is running at 4psi at 3900rpm, the port engine has a Harding pump and it's running 11psi.
The starboard engine isn't overheating, but it seems like it should be higher than 4psi. It's running at 156°, and the port is running at 154°.
I checked the tstat housing and it was clear.
Where else can I check for blockage, or how would I go about back flushing the motor?
 
You only need to look at whatever is directly downstream of the pump for impeller fragments. It should be the oil cooler.

Disconnect the hose at the pump end (the other end should be connected to the inbound side of the cooler). Follow the outbound hose to its end, probably at the heat exchanger if you have one. In my case I found the ID of that hose to be the same as the OD of a male garden hose end.

I made a catcher out of window screen and hose clamped it to the end of the hose I disconnected from the pump and clamped the garden hose to the other end and blasted the cooler clear of bits. It worked great.
 
Could it be a bad pressure sensor
 
Whenever I've had an impeller fail I've always kept all the pieces and reconstructed it on the bench to make sure all the pieces were there. On more than one occasion I've had to chase them down the water passages to make sure I was clear.
 
Just curious why the temp is staying so cool. My boat has never ran 160 in its life. It's always 170 173 could be the gauge I guess
 
Scott215 said:
Just curious why the temp is staying so cool. My boat has never ran 160 in its life. It's always 170 173 could be the gauge I guess
Click to expand...
It could be the ice cold water I boat in. It's always ran in that range, as did my 260.
We can't get in the water here until mid to late July, even then it's cold, it's just hot enough to enjoy the cold water.
 
If your pressure is LOW it is a blockage on the supply side (or impeller or housing is worn). If it was a blockage (pressure sensor is at power steering cooler) it would be HIGH.

I Found zebra muscles blockage in port engine water intake by transom this was why low raw water pressure and was getting worse.
Port intake 3/4 blocked at transom with corroded hose and broken insert.
Picture1.jpg
 
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