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compassrose888's picture
compassrose888
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Joined: 8/17/16
Posts: 10
Loss of water flow out of exhaust

Hi all,
Hoping someone may have some thoughts as to what might be causing low water output from exhaust.
Background - will try to keep it short! 
Mid august fresh water pump fail, replaced
Impeller pump was leaking around the same time so replaced with complete new one (it was sold with the boat) installed new seals and new impellor.
Water flow was good for a couple of weeks.
Now water output is much less and noticed the temp guage is higher than normal but acceptable but only after running 20 min at around 16-19rpms
Boat is hauling in a couple of weeks.  Plan is to go through engine and to also have new injectors put in or clean the old ones (thoughts on which is better?)
One thought is the impellor pump that was sold with the boat was bad?  It looked brand new. I had new seals put in it and after installed worked pretty good for a while. 
Is there any other place I should check for some obstruction?
Any suggestions welcome.
Thanks,
Joy
 

Chachere's picture
Chachere
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Joined: 10/27/10
Posts: 694

Here's some places to look:

First, I would check and clean the strainer at the intake.  That's where I've most often found a blockage problem.

Second (if that doesn't cure it), check the intake seacock.   I've had a few times while underway where it got stuffed up with seaweed (even a floating bit of plastic could get sucked in); close it, undo the hose from it, and then open it (don't worry, there won't be a firehouse of water coming in, its a managable flow) long enough to poke a chopstick or something similar to clear it out.

Third (if the above don't cure), there is the possibility that there is an obstruction in the heat exchanger ("HX").  I've never experienced this, but  have read that sometimes when an impeller fails one or more of the vanes that have broken off travel through the hose to the HX and get lodged there.  So remove the HX, then remove the end caps and flush it out.

 

compassrose888's picture
compassrose888
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Joined: 8/17/16
Posts: 10

Thank you Chachere. I did do the first two on your list. Will check new impeller, installed recently. The heat exchanger was replaced beginning of summer season and while unusual, will check as well.

Pgutierrez's picture
Pgutierrez
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Joined: 5/14/12
Posts: 164

On the Great Lakes & Upper Mississippi River we have zebra mussels that clog up intake lines, showing up in late summer.  The gap between my rudder post and boat bottom skeg (???) in front of rudder post gets filled in by mussels and I have to clean this out after haul out.  Have diver use coat hanger to ream out water intake?  I think more likely you may have pices of old impeller clogging heat exchanger.

compassrose888's picture
compassrose888
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Joined: 8/17/16
Posts: 10

Yesterday she's flowing freely again.  I did nothing! The only difference is warmer air temperatures was in the high 60's yesterday. #scratchingmyhead

pierview
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Joined: 9/27/09
Posts: 505

Had a friend who put in a new impeller but still had over heating. Turned out that the impeller is rubber but there is a ring of metal in the impeller axis hole. The bonding between the impeller and the metal ring was weak and while the ring turned at the normal rpm, the impeller didn't causing it to pump less cooling water. Might want to just try changing the impeler again.

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