'97 Johnson 115 Driveshaft Play

[Cricket Too]

Hey guys, just pulled the lower unit down to do a water pump on this engine which I just bought. Fought me the whole way, finally got the unit down after standing on it and bouncing a bit to get it to drop, then had to chisel the impeller off the shaft, at least I got it though, guess it could have been worse, considering it looks like nobody has had this lower unit down in 10 years, all pump parts look original 1997.

Anyway, I noticed that the driveshaft has some play in it, both back and forth and up and down when you pull up on it. If you push it back and forth(side to side), it will move about 1/16 of an inch at the base, maybe a little more, in any direction you push, it is way more drastic at the top of the shaft, but that doesn't concern me, since it will be in the crank. If you pull up on it you get about the same amount of play, about 1/16", just feels like a little too much to me.

I've done about 5 or 6 pumps in the last couple of years, on previous boats and on friends boats, and I don't remember there being that much play in the shaft, but I could just be overly cautious or losing it, figured I'd check here before I put the new pump on and stick the lower unit back up.

Thanks, Mike.

 

[ob]

Re: '97 Johnson 115 Driveshaft Play

The up and down(axial) play wouldn't concern me as much as 1/16" of radial or side to side near the pump housing end.Sounds like you have a bearing and or shaft issue.Any signs of water intrusion into the gearcase?

 

[Cricket Too]

Re: '97 Johnson 115 Driveshaft Play

Hi ob, I re-measured the movement of the radial play and when I measured more precisely, it looks to be more like 1/32" in movement, I first did it last night after working all day and was a little tired so I measured it fast. Should have measured a little better before posting.

There isn't a whole lot of water intrusion in the gear oil, but there is some. When I bought the boat the dealer said the engine had been winterized, so I'm assuming they changed the gear oil before the winter. The only exposure it's had to water since that gear oil was put in was in February when I test drove the boat, so it was probably in the water for a total of 2 or 3 hours and only actually running for about a 1/2 hour, so it didn't have a lot of time to get much water in it, but it does look like some did get in, in that short time.

Is there supposed to be any radial play at all in a driveshaft? It just seems that I don't remember the other lower units I've had apart having any play or any overly noticeable play, but then again it's been about a year since the last time I've had one down.

What possible problem could this cause if it were to run with some radial play in the driveshaft? I did notice some scoring on the driveshaft where the top of the old water pump housing ended and also a slight bit around where the bottom plate is, not bad, more just shined up in those spots that deeply scored. It definitely seems to me that this pump has never been changed in 10 years.

Not sure where to go next. How can I know for sure if I have a bearing problem?

Thanks.

 

[ob]

Re: '97 Johnson 115 Driveshaft Play

Not sure what you're using to measure with but for an absolute accurate reading we'd use a dial indicator.That said ,if the radial movement of the shaft is indeed 1/32" ,that equates in the ballpark of .030",which depending on how high above the driveshaft bearing the measurement was attained,could be acceptable .Normally there will be some radial play detectable.
The water in the lower unit could be from a number of locations to include the driveshaft seal under the waterpump,among others like drain vent screw seals,shift rod seal,or propshaft seals .A driveshaft bearing that is excessively worn would allow for increased radial movement of the shaft thus leading to seal breach or failure.Many times a problem seal is what came first and led to the bearing failure.Another cause for premature bearing failure is misalignment of the shaft between the driver and the driven component.Outboards by design are not that precision with respect to perfect alignment of the driveshaft swing and face and allow for this through the partial flexibility of the floating length of the shaft.Therefore bearings can wear out over their normal run time life expectancy as each machine is unique. Of course ,without my seeing it in person,I can't confidently condemn the bearing.

Note: In the worst case scenario,a complete failure of a driveshaft bearing while running can cause significant damage to gearcase components.If you are in question as to the state of the bearing,I recommend swinging the lower unit into a local dealer or service center and have one of their trustworthy techs have a looksee.

 

[Cricket Too]

Re: '97 Johnson 115 Driveshaft Play

Thanks for the info ob. Yeah I have come to the conclusion that I'm gonna have to take this unit by the local shop and have them take a look, I just don't have enough knowledge or experience, and I don't want to chance it.

Is it hard to replace the bearing if it is in fact shot, or does it require a press? Might be best to just have them replace it as well, as long as it's there. Any idea of what that kind of job would cost?

Thanks.

 

[Cricket Too]

Re: '97 Johnson 115 Driveshaft Play

Just an update for someone doing a search in the future.

Newer long shaft motors have a two piece drive shaft, and the upper shaft has a lot of play in it due to this.

Took my LU over to my local OMC guru and he explained that to me. Seems these shafts used to snap in half due to the length and the vibration, so OMC started using a two piece shaft on the longer ones.....not sure what year this started, forgot to ask.

In searching for this thread to post in it, I found some similar ones, one of which DHP Marine had posted this exact answer in, so I guess I didn't search hard enough the first time.

Anyway still feel better about a pro actually seeing it.

Now I just have to find the time to get the thing back up.