1978 I/O OMC water hookup????

[nocturnaloxygen]

I want to flush my engine to see if the water pump and impeller are working correctley before I take it out on the lake. My question is where do i hook up the water hose on the outdrive. From what I can see there is a water pickup right under the prop, and then there is another hole on the front of the outdrive right near the top (not sure what that's for) This is the first I/O i've owned and the only thing I know anything about is the 302 Ford engine. I upgraded from and 9.6 hp outboard.

Anyway alittle would be great Thanks.

 

[Boomyal]

Re: 1978 I/O OMC water hookup????

Nocturnal, you either need the OMC flush fitting, on one of the pivot trunion caps, (it was an accessory) or you need muffs. Neither one is good for testing the impeller because the hose water pressure can mask the impeller flow.

Loosen up your hose from the outdrive at the thermostat housing, put the boat in the water, fire up the engine and quickly pull the hose. You should have a solid steady stream of water as you have some one increase the RPM up to about 1800-2000K.

Compliments of KaGee

 

[nocturnaloxygen]

Re: 1978 I/O OMC water hookup????

Thanks Boomyal, I looked at my outdrive and I did not have a flush fitting. I guess my other question would be where is the impeller located? is it on top of the outdrive? thanks

 

[whywhyzed]

Re: 1978 I/O OMC water hookup????

Must be 1977, not 1978.

A 1978 can use standard muffs as the water intakes are on the sides of the lower unit. 1964 thru 1977 Electric shift OMC's have a water intake above the prop.

A 45 gallon drum cut in half, fed continually with a hose works well as long as the water level is more than 1/2 way up the drive.

 

[Rob454]

Re: 1978 I/O OMC water hookup????

the water pump impeller is located on the bottom of the upper housing.
I jsut did that for a buddys stringer. We actually rebuilt the whole thing. its a pain cause all of his bolts broke as we took it apart and had to drill and tap EVERY ONE OF THEM. Other than that it was in good shape. We resealed the whole thing and it works great.
Rob

 

[Boomyal]

Re: 1978 I/O OMC water hookup????

Must be 1977, not 1978.

A 1978 can use standard muffs as the water intakes are on the sides of the lower unit. 1964 thru 1977 Electric shift OMC's have a water intake above the prop.

A 45 gallon drum cut in half, fed continually with a hose works well as long as the water level is more than 1/2 way up the drive.

Kj, the flush adaptor pictured above, I ran on my '75 electric shift, then I converted it to the hydro-mechanical in late '79 and used the same fitting. It works well on both units, even up thru the later straight mechanical shift units.

 

[whywhyzed]

Re: 1978 I/O OMC water hookup????

but he wants to test his w/p, so the 45 gallon drum is the only way really besides dumping it in the lake. 78-85 muffs can be used to test w/p, but I think he has a 77 or earlier as muffs are not an option on the earlier drives- barrel the only way on the trailer.
Or, as you mentioned and what I do in the spring - loosen the w/p hose at the thermostat hsg. At idle As i loosen the clamp, water shoots out like mad.....good to go. These old OMC have huge impellers..lotsa flow! no Mercrapper technology here....jabjab

 

[Boomyal]

Re: 1978 I/O OMC water hookup????

....These old OMC have huge impellers..lotsa flow! no Mercrapper technology here....jabjab

That's a fact and I have only replaced mine twice in it's 27 year existance. The first time was 'cause they said it should be done (I never saw the original one) then again when I had my drive gone thru and inspected during my resto. I saw that impeller and it could have gone on pumping for quite a while.

 

[nocturnaloxygen]

Re: 1978 I/O OMC water hookup????

Thanks for all the responses. This has helped me determine what I need to do. I will be asking more questions as time goes by.