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1989 Evinrude 40 Water Pump O-ring Locations

Posted: Sat May 11, 2019 11:15 pm
by Iceboy149
For a 1989 Evinrude 40-HP there are two O-rings that come in the water pump replacement kit #438592, a large O-ring and a small O-ring. The manual does not reference them, and the schematics don't either. YouTube videos show guys guessing of their location.

Q1: Does the large O-ring go in between the plastic pump housing and the metal cup?

There seems to be a groove for it.

Q2: Does the small O-ring go between the impeller and the metal plate?

That does not seem correct to me due to friction, but the videos show that.


Re: 1989 Evinrude 40 Water Pump O-ring Locations

Posted: Thu May 16, 2019 10:07 am
by Oldslowandugly
I have a 1993 48hp, very similar. By the phrase "large O-ring" do you mean the spaghetti seal? It fits into a groove in the water pump housing and seals against the steel impeller plate. The shape of the O-ring is the same as the groove.

As for the small O-ring there is a groove at the top of my drive shaft that it goes on. However there are two O-rings that are part of the shift shaft seal assembly. One large and one small. OMC may have included them in the water pump kit. It is a perfect opportunity to change them since the lower unit is apart from the exhaust housing.

Re: 1989 Evinrude 40 Water Pump O-ring Locations

Posted: Thu May 16, 2019 12:12 pm
by jimh
A detailed pictorial drawing of the assembly of the gear case of a 1989 Evinrude 40-HP outboard engine can be found at the wonderful Evinrude web resource at

Select the BRAND, the YEAR, the HORSEPOWER, and the MODEL. Then click on the link GEAR CASE. You will see an exploded view assembly diagram of the gear case, including the water pump.

Below in Fig. 1. is a thumbnail view. This drawing may be useful for you to discover the location for installation of different O-rings,

Fig. 1. Thumbnail of detailed exploded view drawing that can be seen on the website SHOP2.EVINRUDE.COM.
evinrude40GearCase.png (55.68 KiB) Viewed 4286 times

The resources available for support for Johnson and Evinrude products at the website SHOP2.EVINRUDE.COM are extensive, highly detailed, and unmatched.

Re: 1989 Evinrude 40 Water Pump O-ring Locations

Posted: Fri May 17, 2019 10:21 pm
by Oldslowandugly
Evinrude may have included the two O-rings for another model. That way one pump kit fits many more models.

Re: 1989 Evinrude 40 Water Pump O-ring Locations

Posted: Thu May 23, 2019 10:20 pm
by Iceboy149
Thanks jim and oldslowandugly but no I'm not talking about the spaghetti seal. They're two perfectly circular O rings that appear nowhere on any schematic that I've come across and I've chocked it up to being on different models. What gets me is that there's guys on youtube showing you to put one o-ring under the impeller and to me that would be the worst place possible.

I thought O-rings were meant to keep tight seals, not to be under speed at 5000 Rpms under an impeller.

Regardless, she's pumping water just like she should now....and the O-rings are sitting on the bench. Thanks!

Re: 1989 Evinrude 40 Water Pump O-ring Locations

Posted: Fri May 24, 2019 10:41 am
by Oldslowandugly
Look at the schematic Jim posted. See the two O rings in the shift shaft housing? Do they look like the ones in your kit? I hope they are because it is good practice to change those out when doing the water pump. A couple of years ago I suffered water in my lower unit oil. The prop shaft and drive shaft seals passed the vacuum/pressure tests. But when I moved the shift shaft out came the bubbles. I had to order those seals as they were hard to find. Perhaps because they come in the pump kit and are assumed to be changed with the pump.