US Member - 2 Years
Topics: 18September 11, 2021 at 11:53 am #246491
Set out this morning to replace the impeller in the motor I was given. Front bolt came out, but I didn’t realize it broke until I went to put it back. There was enough rust to provide resistance the whole time I was twisting it and there was never a snap. Had to use vice grips and lube to get it out after I thought it unscrewed. Rear bolt won’t budge and since the other bolt broke, I didn’t worry about horsing it and ended up rounding off the hex head. Pic attached. BTW, the exhaust housing looks much better on the outside than the gear case.
Any suggestions for my next step getting the lower unit off?
Also, I’m thinking that inside the LU extension is not sealed and gets wet, so is there a problem running the motor in a bucket or even on the back of a small boat with one bolt out if the other is locked in place?
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Topics: 78September 11, 2021 at 12:21 pm #246494
Just saw these demonstrated on Chris Fix youtube. Hope the link works .
Good luck. It looks pretty corroded. lots of penetrating oil and time . It will take a long time for it to travel the length of the bolt .
Well, I wouldn’t actually run the engine on a boat with just one bolt attached, except at slow speeds.
You mention the hex head of the remaining bolt is rounded off, so you may just want to drill into what is left of the hex head so it falls off. Trying to use heat at this point won’t be real effective because you can’t really get the heat near where the corrosion is, and you may end up melting the aluminum extension/gearcase.
Once the hex head is drilled off, try prying down to see if the gearcase will come off…The gearcase may come off leaving the extension still stuck, but maybe now you can get the heat inside where it is needed to work the extension down and off, I’m guessing there is plenty of salt/rust holding the bolt shank to the extension housing. Once the extension is down an inch or so, perhaps it is best to cut the bolt shank off between the extension and exhaust housing leaving plenty of the shank exposed, so you can work on that later with heat and vice grips.
Be very careful and patient, excessive heating will melt the thin extension housing and gearcase castings…
Let me know if you have questions about what I have prescribed, I realize that a decent picture would be worth much more than my words…
US Member - 2 Years
Topics: 46September 13, 2021 at 7:25 am #246564
You’re doing this to replace the impeller, right? I had the exact same problem with the same motor. I had to sacrifice both bolts, Heli-Coil both after drilling out the broken pieces, and slit the inside of the housing to get the broken bolt out of the channel. Unless you have a personal interest in this particular motor, or just can’t resist a challenge, I would suggest you look for a parts motor or work on the red Johnson in the background.
TomSeptember 13, 2021 at 3:54 pm #246649
Tom is right, these things are poorly designed from a salt water standpoint for sure. If you must sacrifice a pieces, that extension housing is the best pieces to sacrifice. You surely do not want to ruin the exhaust housing or the gearcase. A replacement extension housing shouldn’t be that hard or expensive to find.
US Member - 2 Years
Topics: 18September 14, 2021 at 9:20 pm #246695
I bought a twist socket set to remove the second bolt but haven’t do so yet. My intent was to change the impeller so that I could run the motor at a meet to demonstrate it runs before finding it a new home. I still might run it as is to show the motor works. I really have no interest in keeping a log shaft motor that requires a regular gas tank, unless I can find a cheap way to shorten it. I’ll talk to some of the old-timers at the Suwannee meet about this option.
I do need to work on the Johnson behind it. It is a ’56 7.5 that runs great but I haven’t been brave enough yet to replace the impeller. I ran it a short while at a meet a couple years ago but I am worried about having to pull the powerhead, which is something I’ve never done. I have a couple ’50s 5.5s, too. I have been thinking about practicing on one of them since I don’t like them quite as much as the 7.5.
US Member - 2 Years
Topics: 46September 15, 2021 at 11:11 am #246711
Pulling the powerhead on a 5.5 or 7.5 is infinitely easier than working on the 4 hp. Probably easier to find parts for, also.
TSeptember 15, 2021 at 2:17 pm #246722
Yes,, pulling the powerhead is no big deal, provided none of the retaining screws is rusted/corroded in place. So, I guess that is where to start…Find a good screwdriver that fits well into those screws….Using an undersize screwdriver improperly will just bugger up the screw heads making the job more challenging. Finding a good screwdriver with a hex grip on the shank to help loosen the screws. It might be easier to tip the engine completely upside down so you can get at the screws more easily. The trick is finding a good way to secure the engine in that position. Some might recommend a hammer/impact driver to help loosen the screws if they are tight, you may need heat also.
Once you have the seven powerhead screws loose, try the four gearcase screws. You are all set if all the screws loosen up without too much struggle. Go ahead and remove the powerhead screws, along with the fuel/air lines and vertical throttle rod. The powerhead should come off now. Disconnect the upper shift rod from the shift lever, remove the four gearcase screws and remove the gearcase as well..
Be careful to note the positioning of all the lower powerhead seal components, this is extremely important.
Let us know how you make out and we will go from there…D
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