Question re: Mercury water pump base O-ring

CWKboat

Petty Officer 1st Class
Joined
Jul 9, 2008
Messages
243
Hello, I am overhauling the water pump assembly on a 1986 XR2 150 HP. I purchased the complete overhaul kit from Sierra via iboats.

My question is concerning the O-ring that goes around the outer diameter of the pump base insert. I discarded the OEM O-ring prior to receiving the Sierra kit - so I do not have the benefit of comparison. The Sierra kit had 4-5 different O-rings. The outer diameter of the base is slotted all the way around for the O-ring. Each one that I tried was too thick and would not enable the base to fully seat. Even tried putting the old pump housing over it and tightening down, but once removing the pump housing, the base would pop back out.

The only one that would work was a more narrow one that did not completely fill the slotted groove around the outer diameter. It did extend out over the outer diameter some to provide a seal, but intuitively it seemed that the O-ring should completely fill the slotted ring. But this one was the only one that would work because all the others were of the same thickness, and would not go down no matter how much I tried .

I was wondering if anyone here has used the Sierra kit and/or ran into similar issues?
I went ahead and out the pump assembly together, but it didn't leave me with the greatest peace of mind worrying that I used the wrong O-ring, but it was the only one that would enable the base to "pop in."

Sorry, I don't have pictures, but I'm sure anyone who has replaced this assembly will be able to visualize what I'm referring to. Thanks for any feedback/suggestions!
 

marcw21

Recruit
Joined
Mar 1, 2011
Messages
2
Re: Question re: Mercury water pump base O-ring

"The only one that would work was a more narrow one that did not completely fill the slotted groove around the outer diameter."


That was the one i needed and used! I have a 1990 Blackmax 135 so it should be the same.
 

CWKboat

Petty Officer 1st Class
Joined
Jul 9, 2008
Messages
243
Re: Question re: Mercury water pump base O-ring

"The only one that would work was a more narrow one that did not completely fill the slotted groove around the outer diameter."


That was the one i needed and used! I have a 1990 Blackmax 135 so it should be the same.

Marc,

Thanks, that makes me feel a lot better. It was the only one that would enable the insert to pop in, so I'm going to trust that it works, thanks!
 
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