rdenis
Seaman Apprentice
- Joined
- Jul 3, 2010
- Messages
- 32
I just changed the impeller and driveshaft seals on my 1979 Johnson 115 HP - in another thread I posted my travails of getting the drive shaft splines to release from the crankshaft spline hub when I was releasing my lower unit.
New seals are great and have solved the lower unit water problem. However I fear I have created another problem. In my haste to get back on the water and fear of my splines getting stuck again I liberally applies Honda Moly 60 to my drive shaft spline taking care not to get paste on top of the drive shaft - for fear of creating to much presure on the crankcase.
So put the boat in the water this morning and fired her up - hhmmm first thing I notice is she is taking longer to warm up than usual - takes several minutes to get an idle which doesn't require the warm up lever.
I started the motor with the boat still on the trailer but once she was was idling I figured time for a real test. Put her into reverse and I can't get enough power to back off the trailer - hhmmm, weird me thinks. So my wife gives the boat a gentle nudge and off I go.
I start off slowly and give the new seals and impeller a chance to work a bit. Just slowly cruising at about 1500 RPM - I have a 17 pitch prop on that tops out at 5500 RPM so pre-seal and impeller change. After a few minutes of puttering about I decided to open her up a bit more...
2000 RPM at WOT????? WTF???? Turn the boat around and bring her back. Load her up on the trailer and then start replaying the last 4 days in my mind of everything I did in chanign out the seals and impeller. Unfortunately I ran out of time for the last step of actually water testing the motor at home so this morning on the lake was the first test.
So, here I am in my hotel room 3 hours from home thinking what is causing the issue? I thought maybe the impeller or the new drive seals are causing too much friction but that seems absurd the more I think about it.
I suspect I've put too much spline grease on which got pushed up between the top of the drive shaft and spline hub which is putting too much pressure on the crankshaft causing the engine to overwork.
Another reason I think this is previously when I would start the boat, the motor would almost immediately over-rev when the warm up lever was fully up. Now the motor goes to only 4000 RPM and holds there with the lever up.
So I am going to go buy some tools and remover the lower unit and clean out the spline grease and redo it. I'll also check my throttle linkages although I did not change them when I removed them so not sure why they would be out of wack now - maybe the kids were playing with them, who knows?
So does anyone else have any ideas as to what is the likely cause? Am I on the right track with the spline grease or do you think that is unlikely? (Another reason I think the grease could have got pushed up is I had to drop the lower unit after reinstalling since I realized I had forgotten to put the exhaust housing back in - Doh!)
New seals are great and have solved the lower unit water problem. However I fear I have created another problem. In my haste to get back on the water and fear of my splines getting stuck again I liberally applies Honda Moly 60 to my drive shaft spline taking care not to get paste on top of the drive shaft - for fear of creating to much presure on the crankcase.
So put the boat in the water this morning and fired her up - hhmmm first thing I notice is she is taking longer to warm up than usual - takes several minutes to get an idle which doesn't require the warm up lever.
I started the motor with the boat still on the trailer but once she was was idling I figured time for a real test. Put her into reverse and I can't get enough power to back off the trailer - hhmmm, weird me thinks. So my wife gives the boat a gentle nudge and off I go.
I start off slowly and give the new seals and impeller a chance to work a bit. Just slowly cruising at about 1500 RPM - I have a 17 pitch prop on that tops out at 5500 RPM so pre-seal and impeller change. After a few minutes of puttering about I decided to open her up a bit more...
2000 RPM at WOT????? WTF???? Turn the boat around and bring her back. Load her up on the trailer and then start replaying the last 4 days in my mind of everything I did in chanign out the seals and impeller. Unfortunately I ran out of time for the last step of actually water testing the motor at home so this morning on the lake was the first test.
So, here I am in my hotel room 3 hours from home thinking what is causing the issue? I thought maybe the impeller or the new drive seals are causing too much friction but that seems absurd the more I think about it.
I suspect I've put too much spline grease on which got pushed up between the top of the drive shaft and spline hub which is putting too much pressure on the crankshaft causing the engine to overwork.
Another reason I think this is previously when I would start the boat, the motor would almost immediately over-rev when the warm up lever was fully up. Now the motor goes to only 4000 RPM and holds there with the lever up.
So I am going to go buy some tools and remover the lower unit and clean out the spline grease and redo it. I'll also check my throttle linkages although I did not change them when I removed them so not sure why they would be out of wack now - maybe the kids were playing with them, who knows?
So does anyone else have any ideas as to what is the likely cause? Am I on the right track with the spline grease or do you think that is unlikely? (Another reason I think the grease could have got pushed up is I had to drop the lower unit after reinstalling since I realized I had forgotten to put the exhaust housing back in - Doh!)
