Do I have the right pump?

[Anonymous]

Didn’t the shape of the anti-ventilation plate change in the later engines?
Wasn’t the trailing edge rounded in the old ones, and straight(er) across on the new ones?
Can you post a shot of the whole lower unit from above??

I was surprised when I saw that Dean Purcell’s "Workhorse" (a reincarnation of the Gale 15hp) had the newer lower…..

Wasn’t dark green used on newer Johnson 18ci lowers?

[vintin]

Here’s a photo of a 1969 25hp lower unit. The photo doesn’t show it well but the trailing edge of the ventilation plate is not rounded.

[fleetwin]

OK, so you just got it and it has never pumped….I looked in the 69 parts book, and it shows the newer style 313543 impeller housing and the impeller housing spacer/tube. So, that impeller housing you have is wrong for the 69 25hp….You mention that the tube spacer is cut off, go ahead and post a picture of that.
So, I guess I would try to find an affordable impeller housing/SS plate/impeller, and get the tube/spacer situation straightened out. I’m guessing someone cut the spacer down because they couldn’t get the gearcase all the way up into the exhaust housing with the older style impeller housing.
I don’t think the year of the gearcase is an issue, I’m thinking the older water pump pieces would not line up with the newer 79 style screw holes in the gearcase… I guess you could just order one of the gaskets for the 79 style case: 324449 to see if it lines up with the screw holes in your gearcase.

[fleetwin]

Make this guy an offer and get new impeller:
http://www.ebay.com/itm/Johnson-Evinrud … NT&vxp=mtr
Replace that crushed grommet also

[amuller]

From studying the books it does appear that 78-79 was the transition from the metal 3 screw impeller housing to the 4 screw plastic housing with SS liner.

Since my gear case has 4 screw holes and the isolator/spacer had to be cut to fit, I suspect the newer setup is the best one for this situation. Marine engine lists multiple housing and cup numbers, but shop.evinrude only one each. I am as cheap as can be, but with the housing costing $8 and the plate $3 and the cup $14, plus a few $ for gaskets, I incline to just buy the stuff, assuming the rest of the motor continues to check out.

Are there gear ratio differences to look out for?

[amuller]

quote VinTin:

Here’s a photo of a 1969 25hp lower unit. The photo doesn’t show it well but the trailing edge of the ventilation plate is not rounded.

I looked at mine and the trailing edge is sort of veed. Like the leading edge. Not really rounded.

[frankr]

Chrome pump kit has chrome plated liner and plate. http://www.marineengine.com/parts/johns … &sid=36448

Heavy duty clutch dog & gears have three lugs http://www.marineengine.com/newparts/pa … num=391019

[fleetwin]

OK, well now I am sorry I started mentioning the 79 gearcase. For me, there are a lot of unknowns here….But, the older pump stuff does not supercede to the newer plastic housing stuff, so I am thinking the newer stuff will not fit/work on older gearcases. Even if the newer stuff will bolt up correctly, the positioning and height of the water tube in the newer pump is an unknown as well. Like I said, you could just order one of the newer gaskets to see if the bolt pattern is the same, but that only answers just one of the questions, the newer stuff will bolt up…
OK, looks like the water tubes are the same between 78 and 79, but the driveshafts are different….I’m thinking one major obstacle here would be the impeller key, there is a definite difference between the old and new (plastic hsg) impeller key….So, my nickel says trying to use the newer plastic housing water pump on and older gearcase will not work….

[fleetwin]

Here is a new spacer for you:
http://www.ebay.com/itm/Johnson-Evinrud … Swk1JWgAN5
You will need the orings also…
Be careful though, says this auction is from "Cyprus", wherever that is….
Be sure the guy is legit and isn’t going to hit you with big shipping charges…
Don

[amuller]

Yes, there are unknowns here. But based on all said I’m thinking that we have a 1969 leg, with a 1979 or later gearcase. (That based on the four screw holes, the shortened spacer/isolator, etc.) Whoever assembled it used a 3 screw metal pump housing that did not really match the gearcase or the spacer. (But I don’t seen any reason it wouldn’t pump if carefully assembled.)

So it is a matter of using the plastic pump that matches that gearcase, not of trying to use a newer pump on an older gearcase.

What are the differences in impeller key? The one that came out was plain round pin, not the type squared on one end.

What am I missing here?

There is an old-line OMC dealer 20 minutes down the road; maybe I’ll go and see if they are up for a consult.

[Author]

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