Water Pump base part number doesn't match Part number book, is this a problem?

[Mercproject]

I have a 1966 Mercury 650, serial number 1869630 (made in Canada)

The water pump part number stamped into the housing is 46-38931.
The parts manual I have states that a motor with serial number through to 18889735 uses a water pump # C-46-35976A1

Anyone know what difference there is between the two bases?

Did someone install the wrong base once upon a time?

Also: is there a change up to the replacement base number for this motor?
Will a base with a part number 46-58618A1 work?

The installed water pump is metal, I am assuming plastic replacements work just fine. Is my assumption correct?

Water was getting into the lower unit, but I attributed that to a rusted drive shaft - I have a new drive shaft and am reassembling the motor, and rebuilding the water pump.

Any help, suggestions or parts for purchase are appreciated.

Thank you,
Andy K

 

[racerone]

When changing a driveshaft you should check gear shimming / tooth contact / backlash.-------Pump housing parts have been updated over the years.

 

[Mercproject]

Thank you for the tip.

I do have a variety of new shims to be able to ensure sufficient clearances.
I have not been able to find machinists dye any where. Is there a good substitute for checking where the gears are contacting?

 

[Mercproject]

Would anyone have the change up numbers for the base??

AK

 

[Dekker500]

I typed your serial number into the Mercury Parts Express site (https://webapps.brunswick.com/literature/literatureSearch.do) and it does not seem to recognize the serial number. Double-check the number, and try that site. It should give you the "current" part number you are looking for.

 

[flyingscott]

mercury website is only good to the middle 80s after that you have to go to the dealership

 

[GA_Boater]

Would anyone have the change up numbers for the base??

AK

 

[Mercproject]

Thank you for the help everyone, I appreciate it.
The serial number is correct. My assumption was that it is made in Canada. I am now figuring it was made in the US but imported by Mercury, Toronto Canada (On the serial number plate).

Is ther any easy way to check gear backlash? How crucial to the thousnadths? My technique is a little weak.

Thanks again everyone