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1973 25hp evinrude 2 stoke outboard motor gearcase seals

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zommer

New member
Hello , I am putting new seals in the gearcase and replacing
the impeller and impeller housing in my '73 evinrude.
In another forum a guy said to use omc/brp gasket sealant for the
outside diameter of the seals as I replace them and to use between the impeller plate
and gearcase but not between the impeller housing and plate.
He also said I could use permatex sealant that comes in a can with a
brush attached to the lid but not the exact type.
If this is true can anyone tell me if this is Permatex High-Tack gasket sealant #80062.
Thanks for any replys.
 
zommer said:
Hello , I am putting new seals in the gearcase and replacing
the impeller and impeller housing in my '73 evinrude.
In another forum a guy said to use omc/brp gasket sealant for the
outside diameter of the seals as I replace them and to use between the impeller plate
and gearcase but not between the impeller housing and plate.
He also said I could use permatex sealant that comes in a can with a
brush attached to the lid but not the exact type.
If this is true can anyone tell me if this is Permatex High-Tack gasket sealant #80062.
Thanks for any replys.
Click to expand...
You dont need any sealant on the impeller plate!

There's water both sides!
 
Last edited:
vics said:
You dont need any sealant on the impeller plate!

There's water both sides!
Click to expand...

Thanks for the reply.
I didnt see any sealant when I opened the water pump up.
But this guy said I only needed it on the gearcase side and I saw none
there either.
My repair manual does say that I need to put omc/brp sealant on
the seals that im changing in the gearcase.
The driveshaft seal and the gearcase head assembly seal.
Thats why I wanted to know if I could use the permatex high-tack sealant
for that.
I do have scotch-weld 847 adhesive to seal the gearcase halves
back together.
Would it be ok to apply that to the o.d. of the seals as im installing
them back or should I try to find the omc/brp sealant ?
 
I suppose the high tack will work just fine but I use a light bead of loctite to seat the seals. Be real careful not to get anything on the rubber part I keep a damp rag with acetone ready just in case for a quick wipe.
 
Good Grief. I guess I am "The Guy" and it seems my credibility is in doubt. In the other forum I said that the type of sealant you use around the OD of the seals really isn't critical. Heck, it really doesn't matter all that much if you put them in dry. I also said that you can use your 847 on them, saving running out to buy more stuff. The Pematex #3 Liquid is a fairly close substitute for the gasket sealant, but nastier to use. I'm posting the page from the service manual where it says to use Sealer 1000 UNDER the plate. Sealer 1000 is obsolete, and replaced by Scotch 847. Don't use it between the plate and impeller housing because it can goop up the impeller if you slop on too much. There is EXHAUST under slight pressure on the outside of the water pump---the reason for putting the 847 under the plate, which is to help keep the exhaust gasses out of the pump.
 

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vics said:
You dont need any sealant on the impeller plate!

There's water both sides!
Click to expand...

zommer said:
Thanks for the reply.
I didnt see any sealant when I opened the water pump up.
But this guy said I only needed it on the gearcase side and I saw none
there either.
Click to expand...

Sorry but having now checked with the manual i see that it is advised to apply sealant to the gearcase under the impeller plate
 
All it takes is a small nick in the housing for the pump to suck air under the plate just a real thin coat of sealant is all thats necessary.
 
fdrgator said:
Good Grief. I guess I am "The Guy" and it seems my credibility is in doubt. In the other forum I said that the type of sealant you use around the OD of the seals really isn't critical. Heck, it really doesn't matter all that much if you put them in dry. I also said that you can use your 847 on them, saving running out to buy more stuff. The Pematex #3 Liquid is a fairly close substitute for the gasket sealant, but nastier to use. I'm posting the page from the service manual where it says to use Sealer 1000 UNDER the plate. Sealer 1000 is obsolete, and replaced by Scotch 847. Don't use it between the plate and impeller housing because it can goop up the impeller if you slop on too much. There is EXHAUST under slight pressure on the outside of the water pump---the reason for putting the 847 under the plate, which is to help keep the exhaust gasses out of the pump.
Click to expand...


I certainly did not mean to insult u fdr.
I have gotten different answers from different people
and trying to learn what I should be using and doing as I replace the seals.
This is my first time working on a gearcase and have learned
all I know from utube and a few forums trying to peice
together all the info. I need.
I will use the 847 around the seals and under the impeller plate.
Would it be ok to use a thin film under the housing as
kimcrwbr1 suggested incase of a nick in the housing ?

Also should'nd there be a seal in the impeller housing that fits around
the driveshaft. The old one didnt have one.I thought someone may have
worked on it before and screwed it up and took it out
but the new housing doesn't have a seal either.
Do u know ? It just seems strange that theres not a seal.
The old repair manual I have shows seals and gaskets on the water pump
but it is also covering 1973 evinrudes 20, 25, throught 40 hp
Maybe thats why it shows the seals and gsskets ?
Beats me.
Any help will be appreciated...
 
You can put the 847 between the plate and housing if you think you need to. But it is not necessary. There is no shaft seal in the impeller housing on that model. If you look closely at the housing, you will notice a cup on top, around the shaft. Now look at the hole that the water tube grommet goes into. See that small angled hole between there and the cup? That angled hole directs a bit of water from the pump outlet to the cup, keeping the cup full as it runs. The cup full of water prevents exhaust gasses from entering the pump through the drive shaft hole. Thus it is a water seal and no mechanical sealing device is needed. The engineers took care of all this a long time ago. We can relax, the system works.
 
I meant the gearbox housing not the impeller housing. Just a real light coat of sealant under the impeller plate. The only thing I could figure that weep hole in the housing does is allow water to drain out of the water tube and lower engine when the engine is not running to protect from freezing. Always store the engine in the running position so it will fully drain the water out of the engine. At least that is what I thought it did?
 
kim, you are thinking of the drain hole. I am speaking of the angled hole that FILLS the cup while running. A lot of people don't even realize it is there or why the cup is there, or why there are fins inside the cup. The fins keep the water from swirling and waterpooling as the shaft spins. BTW, if the angled hole is plugged up, it will cause erratic pumping as exhaust gets into the pump.
 

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fdrgator said:
You can put the 847 between the plate and housing if you think you need to. But it is not necessary. There is no shaft seal in the impeller housing on that model. If you look closely at the housing, you will notice a cup on top, around the shaft. Now look at the hole that the water tube grommet goes into. See that small angled hole between there and the cup? That angled hole directs a bit of water from the pump outlet to the cup, keeping the cup full as it runs. The cup full of water prevents exhaust gasses from entering the pump through the drive shaft hole. Thus it is a water seal and no mechanical sealing device is needed. The engineers took care of all this a long time ago. We can relax, the system works.
Click to expand...

Ok fd. Thanks for all the information.
Im going try to put it all back together.
Charles
 
kimcrwbr1 said:
I meant the gearbox housing not the impeller housing. Just a real light coat of sealant under the impeller plate. The only thing I could figure that weep hole in the housing does is allow water to drain out of the water tube and lower engine when the engine is not running to protect from freezing. Always store the engine in the running position so it will fully drain the water out of the engine. At least that is what I thought it did?
Click to expand...

Thanks for the information.
Im going attempt put it back together.
 
zommer said:
Thanks for the information.
Im going attempt put it back together.
Click to expand...


Hello again fd.
Could u please tell me if I can use pennzoil marine hight-viscoity lower unit gear
Lubricant 80w-90 in the'73 25 hp gearcase ?
I can get it easy at wally world but cant find evinrude oil on
a saturday
 
Well. I just got around to putting the gearcase back together.
And I decided to do the pressure test.
I pumped 15 lbs. into the gearcase and it held with no leaks I could find.
But the book says to pump 16 to 18 lbs. into the case.
So I pumped in just a little more and it shot up to 25 lbs
and blew the air throught the seal around tbe propeller shaft.
:(
Have I just ruined the new seals I just installed ?
 
8 lbs is all thats necessary, turn the driveshaft and shift gears while watching the pressure it should not change. If it has back to back seals you want to do a vacuum test as well.
 
I dont think u read my question close enough.
I accidently pumped 25 lbs. of air into the gearcase and it blew air out the seal around
the propeller shaft and blew the driveshaft out of the gearcase.
It shot I to the air.
My question is . Have I ruined the sealsl by doing that ?
 
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