Shurflo macerator pump - Don't read this if you're squeamish about @#$%

[Calypso52]

Shurflo macerator pump failed after a couple years, maybe a couple dozen discharges. Just slowed down, like it was working harder and harder, then stopped.
Since we have a second holding tank aft with a Whale diaphram pump, we mostly used that and just arranged for pumpouts of the forward tank when needed.
I finally tackled the project recently. No small task as we buried the pump in lots of other plumbing (mistake #1) and it was inline with the bottom of the tank(partial mistake #2.) So even after doing a very thorough pump out, there was a quart or so of leftover in the lines, yummy!
Anyhoo, got it out and am trying to get it apart a) to try to figure out why it failed and b) if I decide to keep it to rebuild it.
The three philips head bolts which hold the case together aren't budging. Drenching the seam between the plastic pump housing and the metal motor case with penetrating oil for several days and increasing vigorous "taps" with my impact driver. Nada.
So here are the questions:
Is this particular difficulty related to taking apart a Shurflo?
Are the bolts seized because the pump was continuously bathed in effluent because of its mounting location? Should all pumps be located above the top of the tank. (I don't believe there is anything in the manual about that.)

Some would say, oh just chuck it and get a new one. In that case I'll cut it apart with my grinder to try to determine the cause of failure.

I would put a second Whale pump in here in a heartbeat but that would require some material reconfiguration of the plumbing due to the profile of the Whale. This is one piece of boat equipment we all love to hate.
Any suggestions or commiserations appreciated!

[nes]

Not a specific answer, but a suggestion for future reference, a friend had a problem with his macerator pump not working. I had heard of someone going to a pump out station and while pumping out his tank opening the discharge valve on the pump and pulling water through his pump.

I suggested this to my friend, and it worked for him.

[Calypso52]

Oh and BTW,
Another pump I have as back up, a Jabsco, has a much better design: four bolts instead of three, cap nuts instead of Phillips, and an opening on the body where each bolt goes into the motor housing so you can get penetrating oil in there.

Are you listening Shurflo? Jus saying....

[goboatingnow]

Shurflo pumps are in general junk.


Dave

[Calypso52]

First the good news:
After banging on it for a week, I finally got it apart. Plus one for penetrating oil, an impact driver, a vise and patience.
No clogs. I was expecting a big gob of hair. A little hair but not the cause.
The impeller was intact.

The bad news:
A pile of encrusted salt between the pump assembly and the motor. Shaft is seized. Obviously the shaft seal failed. RIP
NO MORE SHURFLO for Calypso.

[bstreep]

A few months ago, we faced either replacing the diaphram on our Whale pump, or putting in an electric pump. After reading all of the lousy reviews on electric mascerator pumps, we just rebuilt the pump. It ALWAYS works. Yes, it takes about a minute of exercise to use it.