MARK 25 LOWER UNIT

[dfreson]

I just obtained a ’56 mark 25 in original running condition. It needs lower unit seals [they are in the mail]. Here is my question; Is there a way to remove the water pump cartridge without using the special merc tool?

[mercuryman]

Clamp the drive shaft in vice and drive the lower unit off with rubber mallet. It will pull out the cartridge. I have read about this way of removing but never tried it myself.

[jw-in-dixie]

Vice and hammer – that’s the way I’ve been doing it for seventy years. A little heat helps, both ways. Use the oven if Wifey is out. 🙂

[20mercman]

Of course, the drive shaft pinion bolt must be removed first. I use a block of wood to protect the housing from damage to the housing. There is a small alignment pin that keeps the cartridge in the proper position. This will fall out when you drive the housing off of the drive shaft. Pay attention to the shims and return them to the same position.

Steve

[jeff-register]

Block the prop shaft between 2 pieces of wood, Hammer it out, the forward gear will drop off the propshaft. Make a special 6 point box & remove beveling to get a sharp socket to remove the pinion gear nut as it has a slim head & strips easy. noton 2 it. Hope your D shaft is good. Be careful not to lose the shift shaft coup, Mk 25 is different cause of the tower isolation pads, it is flexable.

[billw]

Agreed with all above, especially Jeff’s tip about grinding a short socket to fit fully onto the pinion bolt. The bolt head is quite shallow and usually quite tight. It DOES strip easily.

Long live American manufacturing!

[Author]

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