Square shaft powerhead

[reelfishin]

I have a very low hours, near new 115 powerhead with a square hole in the bottom of the crank, can anyone tell me what years it will fit? Is it strictly Hydroelectric shift only?
I also have a super clean light green lower unit from a V4, will the lower unit from one of these early motors interchange with a later motor?

 

[Joe Reeves]

Re: Square shaft powerhead

Isn't there a model number on that engine?

 

[reelfishin]

Re: Square shaft powerhead

I only have the powerhead and lower unit from that motor. It came out of an older shop on a lake in PA, the power head is complete and all four plug wires come out from under the flywheel. It was given to me along with some other earlier V4 parts along with an old boat. The power head looks new and has perfect and even compression and no signs of any water passage erosion or slat damage. The exaust chamber underneath is mint clean and looks like it may never have been run at all. It was bagged and tagged "115HP OMC". The block is painted sort of a red color and the covers and bolt ons are bare aluminum if thats any clue. I don't see any number plates anywhere on the powerhead. The owner had no idea how long he had it, only that its been around the shop for years. He seemed to think his father saved it from a damaged new motor.
The lower unit is a mint green in color and looks to be the same casting as my 1985 3 cylinder 70HP and my 1976 135HP. Were the lower units all interchangable through the years?

 

[F_R]

Re: Square shaft powerhead

Are you sure that "square" hole isn't actually four splines? Never heard of a truly square one. The 115 with plug wires coming from under the flywheel was made 1969-1970. The reddish paint is a sealer stuff that seals the water passages from corrosion. Since they dip the whole thing, the outside gets coated too.

 

[reelfishin]

Re: Square shaft powerhead

Yep, four splines, it just looks sort of square when looking at it. '69 to 71 is what I was sort of thinking, there are some other parts that were in the same area that were marked '71 OMC V4' so it may all be from the same motor.
Is this only good for those years? All of my motors I have here are newer. 1976 to 1985 era.
I guess if I have to I could look around for an earlier V4?

 

[Joe Reeves]

Re: Square shaft powerhead

115hp four (4) spline shaft = 69, 70, 73, 74, 75, 76 (None later & there was no 115hp in 1971/72.)

The V4 four (4) spline shaft existed in 1971/72 but the hp consisted of 85hp, 100hp, 125hp only.

 

[reelfishin]

Re: Square shaft powerhead

I have a 1976 Johnson 135HP that may need a power head soon. What are the chances that that has the four spline shaft?

Is there anyway I can varify that the power head is a 115 as it was tagged?
I am only going on the fact that I was told it was a 115.
It's complete, carbs, exaust cover, side plates, and starter. It looks almost new other than some dust on it.

The 135 block looks similar but the exaust plate is different and it uses four individual coils for each cylinder.

 

[Joe Reeves]

Re: Square shaft powerhead

The 1976 V4 135 falls into the four (4) spline catagory.

 

[Chinewalker]

Re: Square shaft powerhead

The 1975 & 1976 V4s have the fine spline style units, not the 4-splines. Not sure how far back the fine splines go, but I recently tore down two V4s from '75 and '76 and both were fine splines...
- Scott

 

[reelfishin]

Re: Square shaft powerhead

I tried looking up various year crankshafts for the V4's but there are so many different numbers I can't tell by that method.
I don't want to tear the 135 apart if this power head don't have a chance of fitting, I'll let it go till the end of the season.
I did notice that the parts list for my 135 is pretty much the same from 1974 up to 1979 as far as the V4's go, even the crank stays the same though that span of years.

Does anyone know if I can covert my 1976 135 to the newer tilt and trim like on a 1979 or newer V4? I have a complete bracket assembly off of a 1983 V4 here, and was wondering if I can use it on the earlier motor to replace the older style tilt and trim if I change the whole bracket and pin assembly?

 

[Joe Reeves]

Re: Square shaft powerhead

Scott..... Now that you mention it, that could very well be. I don't exactly recall.

I was simply going by the diagrams, pictures, and graphcs of the driveshafts in the parts books and OMC service manuals. Always possible that they simply used graphics etc from the older models. My apologies for the oversight.

 

[reelfishin]

Re: Square shaft powerhead

Is it posible to make use of any of that earlier 115 powerhead by changing the crank? Or should I just wait and find an earlier motor that needs it?