Quick questionbefore I do this?

Can i drop the lower unit on my 1973 evinrude 18hp to check the impeller and possibly replace it with out have any sort of gasket to reassemble?

i want to pull it apart today but if it's fine as I dont know if it was already rebuilt can I just put it back together?

As far as I understand this. i remove the lower screw on the rod and then remove the bolts on the leg from the lower unit and thats pretty much it. It doesnt say anything about draining the leg, or needing to seal the two part with a gasket when reassembling???

My older 15hp Johnson didn't have a gasket where the lower unit attached to the motor. You'll probably need a new gasket after taking off the impeller housing. IMO, if this is the first time you'll be dropping the lower unit, I'd go over the whole thing as maintenance by a previous owner is always questionable. I had a 48hp Johnson that was supposedly serviced by the shop where the previous owner stored the boat. It had some pretty "mickey mouse" work done to it. I ended up replacing all the seals.

Go here https://www.marineengine.com/ and find the parts diagram for that motor, and see if it has a gasket in there. From a first look, I don't see one. You can also get any part numbers you may need off of it.

Yeah, I just drained the lower unit oil and dropped it. No gasket...there is one for the water pump housing, I believe. But mine seemed in good shape and I did not replace it.

I dropped the lower unit on my 15HP 76' Evinrude and there were no seals. Should'nt be either as long as your just changing the impeller. I think whatever seal there is says in the motor. There is an o-ring at the top of the shaft your impeller runs down. But you dont even have to have it. Doesn't do a thing apparently.

yes thanks for the input.. I live in a very small town so getting parts is very tough.. thats kinda why i hoped to open it up and if iit look good put it back together.. if not i guess i have to order parts online.

thanks for all the comments i guess ill go for it and order parts if i get stuck. my boat arrives in 2 weeks from tracker..so wanted engine to be trustworthy, but also dont want it in pieces so i cant take it out for a spin..lol

The o-ring on the top of the driveshaft is to stop water from running all the way up the driveshaft into the splined area. Even if the o-ring is no longer there or you don't replace it, as a minimum grease the splines that go into the powerhead (only the splines not on top of the driveshaft).

Thanks once again stakker.. I think im finally going to do this..lol its been worrying me for some reason as i really dont want to mess it up.

the spline is the grooved section on the top of the driveshaft isnt it? isnt that where the O ring sits.