1979 Evinrude 35hp 35953A water pump face plate intake hole - large vs. small

[mramend]

Hi folks-

I'm doing maintenance on an old outboard I picked up from my father-in-law. My intention was to replace the impeller but I thought I'd order the water pump kit since I had no idea the condition inside. It drew water ok on full throttle but often struggled at slow speeds and forget about putting muffs on to rinse (it needs to be fully submerged to properly draw well)

So, I open up the water pump and inspect the components. I look at the face plate, on which the impeller rests. The 'hole' looks a bit like a sausage shape, about 1 1/2 inch in length (see photo). I then open up my Evinrude kit and see the hole in the plate is about half that size. The poor schematic drawing for the engine online barely shows what looks to be the longer, um . sausage shape. The kit through online parts stores, Sierra, etc. shows the smaller hole..more of a bean. Pics below show the original plate and the new one on the right.

My question is : will changing this hole have a significant impact on the cooling system? If so, how? The base plate does have some wear and should be replaced in my opinion. It could probably go another season but I'd rather do it right.

Any insight would be greatly appreciated..



Thanks,
Mark

 

[oldboat1]

Plate pn is 323251 2 gaskets: housing to plate, and plate to gearcase.

It appears to me the correct oem plate is in place. If it were mine, I would try to clean up the existing plate with a sanding sponge or something similar.

 

[Faztbullet]

It will be fine, changed several for duck hunters and didn't see any difference in test tank.....

 

[mramend]

So that's 1 for refurb the old and 1 for go for the smaller hole. I'm tempted to just go for it since the small hole seems to be the standard size now... Any other votes of confidence ? ;-)

 

[oldboat1]

Can always drill down to the part on the BRP site: http://epc.brp.com/Index.aspx?lang=E&s1=64768188-8441-4619-bf65-5f5e01f7f567. Some sites show the actual part, and some (incl BRP) give you a view of it in a parts diagram. PN for the plate hasn't changed, as far as I can tell, although Crowley or others might include a substitute plate in the kit -- may be what you have.

Your call. Can always try the replacement and see if you get any cooling differences, either at idle or high speed.

 

[mramend]

Thanks oldboat. I'll just give it go and see what happens! If anything significant I'll report back here.

Cheers,
Mark