Lower unit Sealer?

[hd96cc]

I have a 1954 25 hp big twin. I am changing the impeller. There is not a gasket between the two lower unit assemblies. Should I put silicone between the two halves. There was some prior that someone had applied.
Should this be left unsealed to allow air to escape so that water can fill chamber? Thanks,all input will be greatly appreciated. Chris

 

[scrampbell]

Re: Lower unit Sealer?

my (very) unprofessional opinion is to leave it unsealed. If I'm understanding correctly, that chamber fills with water so there's no need to seal.

 

[hd96cc]

Re: Lower unit Sealer?

Yes.it is below the water line.It had black sealer between the two halves when I disassembled to reach shift linkage coupler.Probably about 1/3 way up the lower unit.Thanks

 

[boobie]

Re: Lower unit Sealer?

Back in the days when that mtr was built we always used what was called "M" sealer between all the mating surfaces. You should go to any BRP dlr and buy a tube of it or maybe West Marine has it. The reason being it can suck air with out sealing. I've had water pumps that wouldn't pump, took them appart and couldn't find anything wrong. Re-sealed them and they worked fine. That's the reason all your newer mtrs have gaskets and o rings at the plates and housings. Sorry, I just re-read your post. As far as the surfaces between the g/c and exhaust housing you don't need any sealer. I was talking about the water pump it self.

 

[hd96cc]

Re: Lower unit Sealer?

Thanks,Boobie I appreciate you taking the time responding.I"ll try and make it to westmarine today and see if they have anything for that application.

 

[wilde1j]

Re: Lower unit Sealer?

Absolutely doesn't need to be sealed. In fact the midsection is full of drain holes, so what would you be sealing anyway?? During normal operation, the midsection has water well above the water pump anyway.

Won't hurt anything, but a waste of time and money.

 

[hd96cc]

Re: Lower unit Sealer?

There are some holes, but there is a channel from the impeller that seems to go to the water tube. Thought maybe this area may need to be sealed to insure water flow is pumping thru engine.Does that make sense?Thanks

 

[boobie]

Re: Lower unit Sealer?

I'm talking about the WATER PUMP ITSELF ONLY. Not the exhaust housing and ect.

 

[Joe Reeves]

Re: Lower unit Sealer?

As Boobie states, sealer should be used between the plate and the lower unit, and also between the water pump housing and the plate.

The reasoning being is that when underway, the water pump is actually above the water line and the sealer prevents any air from possibly being drawn into the pump. It does make a difference.

 

[boobie]

Re: Lower unit Sealer?

Thank you Joe, but you beat me to it as to the why.