Mercury 650 850 1400 1500 water pump change.

[sutor623]

Since you guys have all helped me so much on my lower unit venture (Faztbullet, Emckelvey, ThumbPkr, etc.) that I decided to post my venture, and the differences that I noticed between the 150hp and 65hp housings.

First off, there is a difference in the driveshafts. The early 650 4 cyl. models had the o-ring on the shaft, and the newer motors (as well as the Inline 6's) had the o-ring in the crank. Well this poses for a problem, because if you use the incorrect driveshaft on the 650 then you cannot keep the proper marine grease between the powerhead and the driveshaft, causing them to get stuck, and a big headache during L/U overhaul. (We have pinpointed that the replacement lower unit that I have is off of a 150hp.)



I chose to grind out the slot for the o-ring, instead of search for the elusive tools required to break the lower unit down and try and swap driveshafts. Here is a pic of the finished grind.



Next thing that I thought I would point out are the part numbers of the waterpump kit that I used in my Lower unit.



In the older 650's there was a flush plug in the side of the lower unit housing, that went straight into the waterpump base. Since I was using the housing of the 150, my water pump base was sealed off and does not use a flush plug. So I decided to pop the base out and change the oilseals, o-ring and gasket underneath it. When I got the base out, I noticed that the plastic was slightly warped. NO WAY was I going to risk toasting a motor with 125# across the board, by neglecting to change the base. Luckily I had a good aluminum base off the 650 lowerunit that had seized up. But, the base off of the 650 had one main difference. (Actually it had 2, but I didn't realize it quite yet.) The waterpump base had a flush plug hole in it. Sooooooo, what did I do, I went to Lowe's and got a set screw, put permatex locktite on the threads, and screwed it into the hole to permanently seal off the flush hole.



I came home from work the next day and was SIKED that I was going to be getting my lower unit ready for install. An when I got home I realized that there was another difference between waterpump bases.:facepalm:

I will continue on a reply.

 

[sutor623]

Re: Mercury 650 850 1400 1500 water pump change.

View attachment 125732

As you can see, the size of the bottom of the bases are different. It is IMPERATIVE that you use the proper base width or the water/oil seal will not function properly. So I was disappointed, and had to order a new base. I had a hard time finding what part number I needed, as the lower unit that I have did not take the standard 650 base (which I had the part # for. I ended up using part # 46-57234A 1. It is the base from a Mercruiser, and was ALMOST exact. The bearing cap at the bottom was a bit taller, so I just turned on the old orbital and sanded it down about 1/8" and it worked perfectly.

View attachment 125733

If you end up re-using the base, make sure that you change the two oil seals and O-ring on it. The kit that I used, had the O-ring, but DID NOT HAVE THE TWO OIL SEALS!!! The new base had them in it already though, so I was good to go.

Here is the order that the gaskets, faceplate, base and housing go in.

View attachment 125734

And here is how the impeller is oriented in the housing. The best way to get it in the housing is to put some oil in the housing, set the impeller and key in their proper place on the driveshaft, and then turn the driveshaft clockwise as you gently influence the impeller into the waterpump housing.

View attachment 125735

Tighten the nuts and bolts on the waterpump, in a criss cross pattern, gently and evenly. You want the housing to seat tightly and evenly. Put on the debris slinger (big washer on top of the waterpump) and the o-ring on top of the driveshaft. Then lube up the prop shaft and drive shaft splines. Don't forget to change the drain/fill plug washers! Fill up the lower unit (about 2/3 of a quart) and check for leaks.

AFTERTHOUGHT: The gear ratios are different from the 650 and 850 to all other lower units. They are 2.3:1 and all others that are compatible (housing wise) are 2:1. I will use a slightly larger prop (maybe 2 pitch sizes) to come as close to the factory specs as I can. It is arguable whether the performance of the motor is greatly affected by using the "wrong" lower unit with a different gear ratio. I will chime in when I get my setup wet!!

That's it, good luck and keep that water flowing.

 

[Faztbullet]

Re: Mercury 650 850 1400 1500 water pump change.

Good reply and info. The reason the water pump bases are different sizes is due to the differences in upper driveshaft bearing, you have the preload style(cone&race), solid ball bearing and reverse preload(race& cone) and O.D of base insert and height must be paid attention to as some units the base holds shims in place for pinion height setting.

 

[sutor623]

Re: Mercury 650 850 1400 1500 water pump change.

Good reply and info. The reason the water pump bases are different sizes is due to the differences in upper driveshaft bearing, you have the preload style(cone&race), solid ball bearing and reverse preload(race& cone) and O.D of base insert and height must be paid attention to as some units the base holds shims in place for pinion height setting.

Thanks Fazt. Yeah I guess the more hp calls for a bigger bearing. I sure know that the prop shafts are also a different size. I just figured that you guys spent so much time with me on this that I'd give a little back in return and maybe save you guys some time. I will get the pictures on the 2nd post up tonight, for some reason they didn't work last night......