Replacing O/D, have sea pumps. do I need a Impeller on Lower unit?

[superiormgmtco]

Hello,
I am getting ready to replace my starboard outdrive. It's on a 1988 Thompson Daytona 27" with a Alpha gen 1. The boat has sea pumps and closed cooling. The drive I have to put on it has a impeller in it. My question is, do I just remove the impeller since it has no function with a boat that has sea pumps? I haven't pulled the boat out yet to compare the way it currently is. Since this is a wknd repair I want to make sure that if I need a impeller, block off plate etc. I get it first.

I did ask a few people about this and have got mixed responses. Marina said I need a impeller in the drive for cooling the upper and then let it flow back into the lake.
Another said that I only need to replace the sea pump impellers and that when a boat comes in for service he has only replaced one or the other. Either the boat has Engine mounted sea pumps or impeller in outdrive, and he's never had to change both.

Thanks!

 

[Bondo]

Re: Replacing O/D, have sea pumps. do I need a Impeller on Lower unit?

Marina said I need a impeller in the drive for cooling the upper and then let it flow back into the lake.

Ayuh,... I agree with these guys...

 

[superiormgmtco]

Re: Replacing O/D, have sea pumps. do I need a Impeller on Lower unit?

Hey Bond-o, Thanks for the reply.
I still don't have a clear understanding why it would need it though. I'm pretty sure the upper unit of a outdrive isn't water jacketed for cooling.
Right now the only water coming into the engine is from the sea pump that picks up from the thru hulls.
If the outdrive's did have impellers in them right now I assume their shot because I've never changed them.
I guess I don't want to put money into impellers if their only purpose is to move water around.
Thanks for any input you may have!

 

[superiormgmtco]

Re: Replacing O/D, have sea pumps. do I need a Impeller on Lower unit?

Hers's another thought, when running the boat out of water I use the muff's that hook onto the scups on the bottom of the boat. You would think I would need to put muff's on the pick ups and the outdrive if there were impellers in the drive. But, I have never heard of that either. When I bought the boat years ago the previous owner ran it for me on the trailer. He only used the muff's on the low water pick up's also.
So I'm still undecided