TOPIC: OMC outdrive issues

The most curious symptoms are rearing their ugly head on my new 68 Johnson Reveler. Its the Buick v6 155 hp, with the OMC drive. In a nutshell, the impeller is not pumping water up into the engine. The water is not even making it to the pivot caps. NOW the interesting part is, if i have the lower part of the drive off, and the lower water pump housing exposed, and i put a bucket of water up to it, It sucks the water right up and spits it out an open pivot cap, BUT if its fully assembled and in a very large test tank- it will not suck up any water. The pick up tube is totally clear, as is all channels and water passages. I can even force water up the pick up tube and it will come out the pivot cap, but it wont suck it up! My thought is that there's a gap of air between the bottom of the water housing where the thrust seal ring sits.

Does anyone have a very detailed exploded diagram to let me know what seals or parts must be missing?

Any help at all would be great!

- Grae

Oh if its any consequence, it over heated yesterday and blew apart the wet exhaust elbows on both sides, so its running very hot and getting zero water to the engine.

Go to

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shop.evinrude.com

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For the pretty pictures and views of the part.

I had an OMC that would suck up seaweed, every once in a while and do that, I had to disconnect the water hose at the motor and with a garden hose blow high pressure water backwards thru the system to clear the weeds....all would be well again

Thanks for the info guys. That Evinrude page is great! It would appear that im not missing any parts. Now im wondering if its just that the drive was not fully submerged. I mean, it was probably 3 to 4 inches ABOVE the pick up tube, but maybe it has to be like the conditions of when the boat is actually in the water ( fully submerged )

For sure you need to have the pump IN THE WATER.

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If there is any wear / corrosion in the housing ( worn ) then it is NOT a self priming pump.

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Now that you know this it is time to put in a new impeller or complete kit.

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The impeller may be damaged from running dry.

Looks like i might be missing a few seals, whicj i picked up at the local shop today. Not sure where they fit into the system, but if helps, they are #42 and x2 #43 in the lower gear case group ( 68 stern drive, lower gear case group. Take a peek if anyone has any help on exactly how they mount up. Thanks!

shop2.evinrude.com/ext/index.aspx?s1=8d6b00adc42fc5e76ec376505c0baff6

I somehow doubt that these were missing.

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The lower 2 keep the oil in the lower unit and out of the water supply to the water pump.

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The upper seal keeps exhaust out of the water supply to the pump.

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But in marine repair there are lots of wonderful things done to motors by both shops and boat owners.

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Post pictures of that housing in the as found condition.Show those seals or where they should be in detail.

Well, the larger of the 3 seals sits at the top of the swivel bearing assembly. The rest of them dont appear to have a home at all. BUT i installed the new 310649 ( larger seal ) and that was the fix! That and fully submerging the outdrive and re-assembling the rest of the lower unit, to separate the water pick up and the raw exhaust air coming out. I have a suspicion that this was some of the entire cause all along, but i never thought about it.
The Johnson 16 came to life this morning on Lake Tapps, and easily gets to 35mph. Very fun boat!

Heres the bare swivel bearing housing. THe old seal has been removed in this photo, but other than that, its just how i found it. If you look at the inside wall, it appears to be that there's another large thin seal at the low part of the housing, but i dont see that in the diagram. Also, the inside of the wall has a rubber coating, or sheath, that appears to be glued in place, but has a seam that angles down along the wall.



New seals, The 2 smaller ones that are even shown in the evinrude diagram dont have a home. They are either to big or to small for anything. THe only thing of not is that they have the identical OD as the bottom of the swivel housing ( lower part of the water pump housing )



It does idle kind of low ( listening by ear ) Would the best way to adjust the idle be vie the throttle cable, or at the carb?

Thanks!

- Grae

.......... The only thing of NOTE....... i meant

I clearly see the 2 smaller seals around the lower driveshaft.

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If the 2 seals you have do not fit there, then perhaps you have the wrong seals for the unit.

Ah yes, in the photo, around the drive shaft. These 2 new ones are much bigger. BUT The part numbers match the diagrams! wierd. Oh well, it all works great now~!