1956 Johnson 5.5 hp water pump replacement

[OptsyEagle]

Re: 1956 Johnson 5.5 hp water pump replacement

That 18-2892 is part of the crankcase seal that goes on top of the assembly that goes into the powerhead. It absolutely needs to be there and replacing old ones with new ones is always advised.

You have the right part numbers so I wouldn't worry too much about what sierra calls them. The picture posted by wbeaton above illustrates how they all go together. 5 goes on top of 6, 4 goes on top of 5. 3 goes into 4. 2 goes on top of 3 and 4, and 1 (18-2892) fits snuggly over 2. All of it is held up by a roll pin in the drive shaft and when you drop the powerhead back on the spring pushes the assembly into the crankcase to seal her right up good.

 

[ci2hi]

Re: 1956 Johnson 5.5 hp water pump replacement

Thanks for the follow-up. The part looks easy to fabricate so I decided to make one. I either have cork or I could use neoprene I suppose. The shaft holds it one way and the spring pressure against the stainless washer keeps it up there so there's no abrasive action taking place. I imagine that neoprene won't take the heat as well as cork though. Pretty good design. I'm used to working on the older 35 HP models. The o-ring too won't be a problem . I'm sure the local hardware store has that part too. The specs are in the catalog. I do see that the parts are very important in keeping water from getting into the engine.

 

[wbeaton]

Re: 1956 Johnson 5.5 hp water pump replacement

Thanks for the follow-up. The part looks easy to fabricate so I decided to make one. I either have cork or I could use neoprene I suppose. The shaft holds it one way and the spring pressure against the stainless washer keeps it up there so there's no abrasive action taking place. I imagine that neoprene won't take the heat as well as cork though. Pretty good design. I'm used to working on the older 35 HP models. The o-ring too won't be a problem . I'm sure the local hardware store has that part too. The specs are in the catalog. I do see that the parts are very important in keeping water from getting into the engine.

The cork gasket has to be thick. Much thicker than the cork gasket material you buy for valve covers and such. It is an inexpensive part. I buy them from my local BRP dealer. I don't know what Sierra uses. I use lots of their parts, but some parts I still prefer from the dealer. Nothing special about the o-ring. Your hardware store should have lots of them.

 

[ci2hi]

Re: 1956 Johnson 5.5 hp water pump replacement

I see what you mean about the thickness but I just can't get past the fact that in all the on-line catalogs the Sierra part number describes it as a bowl gasket. I'm going to go for it though and order it (them). They come two to a pack. I found the exhaust housing gasket at the local dealership. The motor runs so sweet and quiet I'm anxious to get it running. The motor I took the lower unit off that I'm putting on the motor that had the lower unit leak and didn't pump well had been slightly locked up. I think that someone changed the pump but didn't bother to replace the cork gasket or o-ring because I didn't see it in there. Do it right and do it once.......right? Thanks !

 

[wbeaton]

Re: 1956 Johnson 5.5 hp water pump replacement

I see what you mean about the thickness but I just can't get past the fact that in all the on-line catalogs the Sierra part number describes it as a bowl gasket. I'm going to go for it though and order it (them). They come two to a pack. I found the exhaust housing gasket at the local dealership. The motor runs so sweet and quiet I'm anxious to get it running. The motor I took the lower unit off that I'm putting on the motor that had the lower unit leak and didn't pump well had been slightly locked up. I think that someone changed the pump but didn't bother to replace the cork gasket or o-ring because I didn't see it in there. Do it right and do it once.......right? Thanks !

I'm sure the Sierra gasket is fine.

 

[ci2hi]

Re: 1956 Johnson 5.5 hp water pump replacement

I have one final question. The cork gasket mates to the block and the stainless washer then would remain stationary as the engine is running. I presume the carbon seal spins with the driveshaft as the engine is running. Since the stainless washer mates to the carbon seal and one is stationary and the other rotates at the RPM of the engine one would think that there would be some wear occuring. Am I understanding this correctly? The carbon seal spins against the stainless washer? The carbon washer must have some properties which lubricate it against the hard properties of the stainless then.

 

[ci2hi]

Re: 1956 Johnson 5.5 hp water pump replacement

Does the cork go up against the powerhead and then the stainless washer up agains the cork? Then the next item going down is the carbon washer. Now the carbon washer spins with the drivshaft as the motor is running and the surface of it must rub on the stainless washer, correct? Apparently it can take the friction?

 

[wbeaton]

Re: 1956 Johnson 5.5 hp water pump replacement

Does the cork go up against the powerhead and then the stainless washer up agains the cork? Then the next item going down is the carbon washer. Now the carbon washer spins with the drivshaft as the motor is running and the surface of it must rub on the stainless washer, correct? Apparently it can take the friction?

The stainless washer is actually brass unless its been replaced. The cork gasket goes against the engine with the brass (stainless) washer under it (raised portion facing up). Then the o-ring fits in the small end of the carbon seal and the spring fits underneth in the big end of the carbon seal. The spring sits on the little brass cup on top of the roll pin. I expect that the carbon seal and everything below it spins, but not necessarily at the full rpm of the motor. There is some wear, but usually not much. There is lots of water in there to lubricate the carbon seal, but it can take the heat.

 

[ci2hi]

Re: 1956 Johnson 5.5 hp water pump replacement

I have one final question. The cork gasket mates to the block and the stainless washer then would remain stationary as the engine is running. I presume the carbon seal spins with the driveshaft as the engine is running. Since the stainless washer mates to the carbon seal and one is stationary and the other rotates at the RPM of the engine one would think that there would be some wear occuring. Am I understanding this correctly? The carbon seal spins against the stainless washer? The carbon washer must have some properties which lubricate it against the hard properties of the stainless then

 

[ci2hi]

Re: 1956 Johnson 5.5 hp water pump replacement

Sorry for the duplicate posts. I wasn't able to find my previous posts and now I see all of them. Still learning how these forums work. Maybe the webmaster can delete them. I suppose the washer is a plated brass like deck hardware. Thanks for everything. John

 

[kevbo]

Re: 1956 Johnson 5.5 hp water pump replacement

Ci2hi,

Just a thank you for starting this thread. I am working on reviving a twin to your motor, (a '62 CD-19) and all the advice you got saved me some grief.

The seal on the powerhead output is known as a mechanical seal. It is similar to what seals the shaft on most water pumps...automotive, agricultural, etc. The AC compressor on a car also has a mechanical seal on the input shaft. Sometimes such are supplied as a sealed unit, so you don't see the the spring, graphite sealing element, etc.

As you figured out, the way it works is that the brass washer is stationary, and the graphite block spins with the shaft. The spring supplies enough pressure that water can't get between them. Graphite on brass is a very low friction combination, basically imune to galling. The water supplies enough cooling to keep the brass from melting, and in this case, there is a little lube from the oily exhaust as well.