Boat re-power project

[Reserector [Veteran Member]]

If you're ashamed to show it, it probably needs more work to be seaworthy. Just saying.

[MarkyB [Veteran Member]]

Oh it needs going through.
Previous owner(s) hacked it up doing an electronics “update”. All I did was run the Evinrude harness (Itself hacked up) to get the boat running.
I do plan to go back and clean up the wiring, and install new gauges.

Took the boat out today, but got an overheat alarm over 2000 rpms.

Went through the upper plumbing and found no blockages.
I did notice water coming from the top of the extension that shouldn’t be there.

I suspect the extension for the water pump is not lined up properly.

I’ll be dropping the lower unit in the morning.


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[MarkyB [Veteran Member]]

So I was flabbergasted to find copper pipe!
But that’s what Evinrude uses to get water to the power head.

Where the lower unit joins the midsection, the two pipes slip together. The midsection pipe was dented, out of round. Probably from a bungled attempt to align the two. Definitely would have caused a leak.
Got a pipe flare from Lowes to round it back out.

That and some RTV and hopefully I’ve addressed that problem.


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[Reserector [Veteran Member]]

Had the same problem when I reassembled my OMC (might as well say Evinrude) drive. I slid the lower unit on with everything on its side, and the copper tube misaligned.
I reworked the tube, replaced some rubber gaskets and it was able to suck water instead of air.
Here's the link with pics: https://mississippi-mud.com/thread-20480...#pid279688

So, I guess, word to the wise: Keep the unit vertical as you assemble it. Otherwise the tube can fall out of alignment.

[MarkyB [Veteran Member]]

New gauges to better monitor pressure and temperature.


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[MarkyB [Veteran Member]]

So the issue seems to be low water pressure.
Should be 3-4 psi at idle building to 20-25 at full throttle.
I’m getting basically nothing at idle and maybe 4-5 psi at speed. This is from a short run we did about ten days ago.


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[MarkyB [Veteran Member]]

Current state.
I tore into the midsection to check water flow.








Perhaps the culprit?? The gasket between power head and midsection.

[MarkyB [Veteran Member]]

So, I have a new gasket and water tube on order.

The water tube has a kink in the bend. It’s not completely closed off, but is restricted somewhat.


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[Reserector [Veteran Member]]

I would look for air leaks on the pick-up side of the pump, also. All it takes is a shrunken o-ring somewhere.
The gasket is likely designed to restrict the flow a certain amount. I know my inboard is that way; restricted just before it dumps out the exhaust to the prop.
Make sure all of your cavities are clear with no old rubber flappers or other parts wedged in them.

Any restriction on the OUTPUT side will INCREASE pressure. Like holding your thumb on the end of a garden hose. Starving the pump, or a malfunctioning pump will cause low pressure.

[MarkyB [Veteran Member]]

I have already replaced the water pump, (before the last outing.) but I’m going to double check my work and make sure its correct.


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