Not pumping correctly...weird problem

[Southtowns27]

I just fired the boat up for the first time this year and I have a weird pumping issue. It's the boat in my sig, 1986 Wellcraft 260 Aft Cabin, Chevy 350 / Alpha 1. It fired right up and ran correctly but I noticed that no water was exiting the center of the prop. Upon further investigation, I found that all of the water was exiting through a hole about 1 1/4" in diameter right above the stbd trim hydraulic lines in the transom assembly (not sure what it's actually called) parallel with and forward of where the exhaust bellows attaches. The exhaust was exiting through that same hole with the water, and also the same hole on the port side but no water. There was some exhaust exiting through the center of the prop, but not a whole lot. I felt the exhaust risers/exhaust pipes, and as expected, the stbd was cold and the port was pretty warm. Just to experiment, I put a pair of vise grips on the the hose from the thermostat housing to the stbd riser and started it back up. Now I had near equal water flow out both holes in the transom mount and both risers/exhaust pipes were just warm to the touch. So what's going on here??? Why do I have all the flow wanting to go to one side? Why is very little exhaust making it out the center of the prop?? The bellows is intact.. Is my water pump just getting tired? Please please please give me some ideas, we want to have this thing out for the holiday. Thanks!!!

 

[MarkSee]

The holes on each side are called idle relief ports and where most of the water should be exiting when running on the muffs.
What rpm were you running? Idle or most around 1,000-1,200 like what is recommended?
If the drive is not all the way down/in then little to no water will be exiting through the prop.

Water will find the path of least resistance and not uncommon to have more water exiting one side than the other and in your case seems like that is the starboard side.

I must say though that no water at all exiting the port side might warrant some further investigation especially if you do run it at 1,200 rpm and still see nothing?
When was the last time the impeller or full water pump service was performed?

Mark

 

[Southtowns27]

Well, maybe all is normal after all. The engine was at idle while all this was going on, not at the recommended 1200 RPM. I had quite literally just bolted on a brand new Edelbrock 1409 and was checking that all out at the same time. Where the boat is currently parked it has a pretty good list to Stbd so that probably explains why the water was all exiting that side. This is my 2nd year with the boat. I have not changed the impeller and I don't know when it was done last. Coincidentally, I picked up a full pump kit today before I even fired the boat up. I figured it's cheap insurance to just change the thing out so that's next on the list.

 

[Southtowns27]

Just a quick update, I changed the water pump out yesterday. The old impeller didn't look bad, but it seemed a bit stiff, not real pliable. I fired the boat back up after I changed everything out, and now it pumps three times the water it did before. I like easy fixes

 

[NHGuy]

That's a win, you just dodged a bullet by changing out that old hard impeller,
Plus you will save the value of the new carburetor in time and repairs. Summer is on!