Johnson 6HP lower unit

[fish56]

Hello all,
Hope your holiday season thus far is going well.
Anyway, I just bought a used 12 foot jonboat and trailer. It came with an older Johnson 6HP, model CD-24D. The motor's in decent shape. My question concerns the lower end. On the port side of the lower end, above the prop shaft area, there's a slightly raised square shape in the casting. Is this normal? I've never noticed this before on any outboard I've owned. It concerns me, as that area has been repainted sometime in the past, maybe to coverup a repair but I doubt it.
One more question. Can someone give me a part number for replacement drive/shear pins for this outboard?

Thank you. Have a great Christmas!

 

[tashasdaddy]

Re: Johnson 6HP lower unit

post a pic of the parts concerned.

Part Number: 0307949
Description: DRIVE PIN 10 PK

 

[fish56]

Re: Johnson 6HP lower unit

TsDaddy,
Thanks for the part number for the pin. I'm adding pics below. Please click on the thumbnails for a closer look. The dark, irregular lines are green metallic paint sags, not cracks in the housing.

 

[fish56]

Re: Johnson 6HP lower unit

Looks like I found my answer on ebay, of all places.
I found a similar motor and when viewing the pictures, I see the square on the lower end of this motor, as well.
At least it appears to be normal. I'll address the corrosion and paint issues over the winter and get this motor up to par.
Thanks again, TD, for the part number on the drive pin.
Bill

Here's a copy of the pic from ebay.

And yet another from ebay. These are both listed as 1968 models while mine is a 1967, but they appear to be the same overall. Maybe the anti-cavitation plate shape is different on the first pic.

 

[F_R]

Re: Johnson 6HP lower unit

I am not sure, but having worked in the manufacturing arena, I think those bumps are locating pads for clamping the casting in a jig for machining.

 

[fish56]

Re: Johnson 6HP lower unit

F R,
That makes sense. When I first saw this on the lower end, I was concerned that maybe water had gotten in and frozen, cracking it and pushing the housing outward. Then I noticed it was just paint sags and that square bump.
Now to find paint to match the lower part of the motor and fix that corrosion.

Thanks!

 

[jay_merrill]

Re: Johnson 6HP lower unit

The bottom photo from EBay isn't a 1968. Look at the prop shaft - it is the type with the cotter key and shear pin at the aft end. It also has the indented ring that is there to help hold the rubber cup type "spinner."

Obviously this doesn't affect your concern, but it is a good point about buying stuff on EBay. Lots of times people make innocent mistakes in listing what they have, just because they don't really know. In this case, it could be a big deal to a buyer because the only 6hp OMC that the older gearcase would fit is a 1965. As we discovered in a very long thread about this months ago, 1965 was a transition year when OMC used the gear case and a few other things off of the 5.5 hp models.

 

[fish56]

Re: Johnson 6HP lower unit

Jay,
I copied and pasted your response in an email to the ebay seller. Seems like a nice guy. Here's his response:

I appreciate the info; but this unit will fit 1965 thru 1968. Everything is the same on all four years with the exception of the prop shaft. To use this unit on a 1967 model (Evinrude or Johnson); you would only have to change the type Prop you used. I know this for a fact, because I have all four years and also have a huge collection of parts manuals for all years. Thanks again.Sincerely;Jack (oldevin1)

 

[jay_merrill]

Re: Johnson 6HP lower unit

Here's a thread for you to read on the subject. I used to think that you could swap any of them too, but there are issues that complicate things a bit. One thing that I noticed just now, and missed during the course of the conversation at the time, is that you may be able to use the older gearbox in motors later than 1965 as long as you have the drive shaft that goes with that gearbox.

Another issue is whether or not this seller is describing the gearcase as a 1968 model year unit, which it isn't. That's important for several reasons. One is the driveshaft length issue, another is the fact that props for the old style propshaft are becoming scarce, and the last is that parts for the shock absorption system in them are very hard to get.

http://forums.iboats.com/showthread.php?t=232496&highlight=6hp+gearcase


PS: I just found the ad that you referenced. The seller says that the gearcase is off of a 1965 6hp motor, but claims that it can be used up to 1968. He does disclose that "a different" prop must be used. He does not mention the driveshaft issue. He then goes on the state that the gear box can be used on some 10hp models. I have no idea whether that is true or not.

Anyone have any info on this?

 

[F_R]

Re: Johnson 6HP lower unit

The 6 and 9.5 and 10hp gearcases are similar, but I would be quite sure the innards (bearings) are different. In the first place, the 9.5 and 10 do not have a shock absorber. Let's just say it won't work, without wasting a lot of time figuring out the differences. And no, you can't use a 10 drive shaft to replace a broken shock absorber. That bridge has been crossed before.

 

[jay_merrill]

Re: Johnson 6HP lower unit

The 5.5 and 9.5 gearboxes do look similar, but I believe they are shaped somewhat differently in the area where they mate with the midsection. I'm also thinking that they are not at all interchangeable.

If there is any compatibiity between the 5.5 gearbox and any other motor, I would think that it would be the 7.5 hp models.