Water pump tube seal too long?

crabmagic

Recruit
Joined
Apr 11, 2020
Messages
2
Hey folks,

Got a specific question...hopefully some mechanics will have crossed this bridge already.

Noticed last time on the lake the water pump outlet on my 1998 Merc Bigfoot 60hp 2-stroke (s/n OG661xxx) was not jetting water very well at all, resolved to just replace it myself. Not sure if it had ever been replaced, tbh - bought from an older fella.

Took the lower unit off, noticed one the tube seal/collar o-rings was damaged/warped, and the seal itself (which appears to be all plastic) is damaged in the the retaining ridge for the upper o-ring only covers half the o-ring - the rest was hanging like a hangnail...

Went to my local Merc service/sales shop and they got me the water pump replacement kit for my serial, which comes with replacement water tube seal and all the other gaskets/rings and a new ummm...mounting plate? (apparently that was changed to a lower-profile design in later versions of this engine).

Got everything put back together on the pump with no trouble, just like i took it apart, using the new parts. Greased up everything that needed it, and started sliding the lower unit back into the crankshaft case. Got to about 0.5-1” from getting the pieces flush when it was like...nope, this isn’t going in, something is in the way,so i took the unit back out.

Inspecting the new tube seal and comparing to the old one, it’s almost twice as long...the guy at the shop told me the mounting plate is a lower-profile plate, and that accounts for the difference in height. Nope - when I got home, I found they were identical.

But, when I put the old tube seal all the way up/onto the water tube in the bottom of the crankshaft case, the water tube comes out almost to the edge of the seal. When I do the same with the new seal, whaddya know...the water tube extends to about 0.5” or so from the bottom of the seal.

To test the theory, I put the old tube seal on, and the lower unit slides right in like a champ.

Has anyone run into this? I’m getting the feeling that there’s a way to install it that skips that 0.5” mounting plate, which would lower the entire water pump profile by that amount, which should mean i can get lower unit back on...
 

crabmagic

Recruit
Joined
Apr 11, 2020
Messages
2
Hey all,

Contacted Mercury directly:

Thank you for your e-mail regarding your Mercury engine, serial #0G661xxx. We appreciate the opportunity to respond to your concerns.
It sounds as though the water tube coupling that was in the kit you purchased was for engines with a standard gearcase. The Bigfoot gearcase uses a different coupling. From what we can see the coupling needed for your engine is 826763A1. If you google that part number you will be able to see an image of it on google images. It looks like what you are describing your original coupling to be and shows up as the correct part per our parts catalog.

A quick google, and bam - there’s the part.

Bought two, and looking forward to installing this weekend.
 
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