Water pump warning and question

[sagablu]

Hey All,

So I recently rebuilt the water pump">raw water pump for my Yanmar 3GM30F. inner bearing just turned to dust, seal leaking, the usual. All went well except the race was stuck inside the housing, took a bit of work to get it loose.

To the point. While apart I removed the hose from the pump to the heat exchanger. I was squeezing the hose to determine its condition and I felt a hard spot. I ran a fish tape down the hose and a few blades from an impeller came out. Mind you I have owned this boat for 2 1/2 years and never lost an impeller blade. The overheat alarm never sounded and it was pumping water. So who knows how long this was in there. So check your hoses for obstructions when inspecting an engine with unknown service history. Pumps a lot more water now.

Question, so I pulled the cover to the heat exchanger, no impeller debris in there, but I wanted to pull the core for cleaning. Its stuck ( big surprise). I tried gentle tapping and twisting, nothing. How do I persuade the core out without damage?

[NoTies]

Why remove the core? Clear any blocked tubes and give it a 6% hydrochloric acid bath.

[sagablu]

Originally Posted by NoTies

Why remove the core? Clear any blocked tubes and give it a 6% hydrochloric acid bath.

Ok, but how do I soak it in HCL while the core is still in the housing?

[Steadman Uhlich]

Originally Posted by sagablu

Ok, but how do I soak it in HCL while the core is still in the housing?

See the following video.

https://youtu.be/u4bGiv2MD74

[a64pilot]

I wouldn’t, I’d continue the gentle tapping until I got it out.
I found out when I put my Yanmar tube stack in acid that it is either heavily zinc plated or some of it made from zinc as the metal itself reacted with the acid. So no more acid cleanings for my 4JHE heat ex.

[NoTies]

WOW, zinc plated cooler tubes, engine manufacturers must be getting real dumb.

[a64pilot]

Well, this is a 1987 engine, and since seeing it, I have sort of figured maybe the zinc is sacrificial, cause there are no zincs in my cooling system, anywhere.
If it’s not zinc, I don’t know what it is, its dully grey in color and highly reactive to muratic acid.

[NoTies]

That's a pretty accurate description of calcium.

[Nicholson58]

Originally Posted by NoTies

Why remove the core? Clear any blocked tubes and give it a 6% hydrochloric acid bath.

Agree, don’t disassemble. Clean it yourself or take it to e specialty shop. As to the blades, lucky you.

Consider owning a spare heat exchanger.

[sagablu]

Originally Posted by Nicholson58

Agree, don’t disassemble. Clean it yourself or take it to e specialty shop. As to the blades, lucky you.

Consider owning a spare heat exchanger.

I can't take it anywhere because I can't get it out. Maybe running a deposit cleaner through it will loosen it up.