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96 Johnson 48 SPL running

C

crab.net

New member
So I was able to finally able to get my Johnson 48 running (work kind of got in the way) and it's running great at idle and low speeds thanks to everyone's help here on the forum! Now bear with me as this next part gets a little lengthy.

When I first got the boat the manual tilt/trim cylinder had seized up and wouldn't allow me to lift the motor. I drained the cylinder and the motor lifted fine. I changed the gearcase oil and water impeller and everything was running perfect (the boat would run at low speeds and high speeds with no issues). A few weeks ago I lost all forward gear and partial reverse (lucky I was able to reverse back to the boat ramp). When I pulled the boat, I realized that 3 of the 4 bolts holding the lower unit on were missing and the last bolt was hand tight. I must have forgotten lock-tight when I put the bolts in. I got the boat home (luckily with the lower unit still attached) and replaced all the bolts with brand new bolts, washers, and lock-tight. When I put the boat back in the water, the boat started and ran fine at low speeds but when I went to give it more throttle (anything more than roughly 6 knots) the motor begins to rev really high. It almost sounds like it isn't drawing in enough water or the motor is sitting too high out of the water. Also, when I put the boat in reverse and give it a decent amount of throttle, the motors lifts up pretty high and I go nowhere. Based on all these factors I am thinking the motor is sitting too high out of the water and at higher speeds it is almost coming out of the water (hence not going anywhere and the motor revving up really high). So my question is would the problem be that tilt/trim cylinder and it not allowing the motor to go to the correct height? This is what I think but I'm not quite sure as the motor was running fine (at all speeds) before I had the problem with the lower unit coming loose. Could something of happened when the lower unit came loose? I am hoping everyone here who is much knowledgeable than I am can help me out with this issue.
 
My observations may be off some in case I didn't quite understand you post.

How long did you run the motor before you noticed the bolts were gone? If they fell out that easy either they were left very loose when installed or the threads in the motor are screwed up.

I'd pull the lower unit and disassemble it to see if anything is damaged. Also check the drive shaft for straightness and look at the splines. You'll regret using Loctite on the lower unit bolts when it comes time to pull them. I only put OMC Gasket Sealant on mine to minimize corrosion.

Your tilt/trim keeps the motor from raising up out of the water when in reverse. There may also be a tilt lock in front of the motor just under the cowling. If so flip it over for reverse and then back over for forward in case you hit anything in the motor while motoring.

If you haven't already done it yet you need to fix the tilt/trim.


Bill
 
Bill,

Thanks for the help. I don't think I ran the motor for long with the bolts loose but I cannot be too sure. I've only taken the boat out maybe 5 times after getting it running before I had this issue. On the day I lost my forward gear, the boat idle out fine and started running up on plane fine but it was a little rough out so I cut it back a bit and when I got to my fishing hole and put the boat in neutral and then went to put it in drive again is when it would not move. I had to reverse back to the dock. When I pulled the boat out of the water and began looking, I noticed 3 of the 4 bolts were missing. But I had just run the boat a day prior and it ran fine (at all speeds) so that makes me think the lower unit was bolted securly the day prior but I can't be sure.

So you say I should pull the lower unit and check for damage. Does this require disassembling the gear case itself? I probably would let a mechanic mess with that since I believe it is a completely sealed unit. I would assume that if the Splines were worn down they would look like an old worn down gear or possibly even pieces may be broken off? My next question would be that if I messed up a gear or one of the splines, wouldn't I hear like a grinding noise while driving? In my case it is more like when I give it anything more than half throttle it just revs up really high but doesn't push the boat anywhere.

For the Tilt and Trim issue I guess that explains why I have an issue with reverse since the tilt/trim cylinder is no longer functioning. That makes sense because when I put the boat in reverse, the motor looks like it is going to come out of the water and that is why I am not getting any power in reverse. I was considering replacing the manual tilt/trim with an electric tilt/trim unit such as CMC. This would correct that problem correct?

Sorry for all the questions as I am kind of new to outboards. I appreciate all of your help!

Thanks,
Greg
 
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