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Topics - jonathanc34

#1
I blew the diodes on my 1988 M25XP 51a Motorola, which is fine: it had a wobble in the shaft and has done its duty.

(I mistook the Reg terminal for a Voltage Sense terminal, and it didn't like that. If someone could explain what that Reg terminal is actually for, I'd appreciate it.)

I ordered a 51a replacement on Amazon from RareElectrical for $165, needed to get one quickly for vacation next week.
I also ordered the 105a replacement and a new pulley from catalinadirect for $210 because it comes with the 2" adapter, but it won't arrive until Monday. I could not find a direct-fitting replacement 90a or 105a on amazon. I expect I will install the 105a and return the 51a.

The new one pictured below has the same connections as the factory with the addition of a sense wire. The one from CD does not have a sense wire, but does have a voltage adjustment on the regulator to compensate for longer cable runs.

Here are some pictures of the two side-by-side.

My house bank is 4x 6v 230ah. We have a 12v fridge, 1500w inverter for a 700w microwave that we use frequently, 12v fans that run many nights on the hook. We also have inflatable paddle boards that pump to 15 psi using a 120w pump. There have been mornings where the house bank did not have enough power to start the engine.

Any thoughts or observations? Should I wait on the 105a from CD and use it?
#2
I searched, but the words used to describe this are very general terms.

On several occasions after sailing and heeling, we have started the engine only to discover the raw water is not coming out the back.

The fix is to quickly loosen the screws on the Oberdorfer pump housing, which seems to let air escape along with some water. After retightening the
screws, the pump works perfectly, water emerging happily out the back.

I also tried loosening the drain plug this time (before loosening the impeller screws), and nothing emerged at all, which surprised me. Could that indicate that the impeller was not turning?

I cannot reproduce this in our slip: every engine start works without fail.
The impeller is new; the intake filter is clean.
Sailing and heeling seem to be the variable.

Please guide my further diagnosis. :)