LET'S DESTROY AN OUTBOARD - or How I Failed to Kill A Johnson 9.9, Despite Expert Level Execution
I haven't told this story because it's like taking the walk of shame.
Due to my own careless bull-headedness, I nearly burned up the Johnson 9.9.
Here's how it went down.
Before July 4th, my wife had a brilliant idea...she wanted to put the boat in at one end of one of the local lakes and go to the other end in order to watch a fireworks show over the dam.
Of course, this meant coming back at night, which was fine. My boat has nav lights and I have a big spotlight. I'd put the wife up front and she could watch for hazards, and I would have a pre-made path on the GPS so that I could stay right in the channel and avoid shallow spots.
Let me preface this by saying I was messing around with some props to see if I could find a better combo for running with a passenger. So, I dug out an old 8 pitch prop to hopefully give the old Johnson a little bit more oomph and RPMS with another person along.
When I say old, I mean, it was the prop that came with the motor. It is likely this thing has been on the motor for decades. It was beat up, scuffed, and had some chips out of it. I took a Dremel and did a little filing to hopefully make it a bit more efficient, then hit it with a coat of black Rustoleum Appliance paint, and it actually looked pretty impressive.
So, with the "new" old prop in place, we set out to go from one end of the lake to the other. We arrived in plenty of time to find a spot, anchor, set up lawn chairs in the bottom of the boat, and relax and watch the fireworks...
On the way back is when our problems began. Actually, we made it almost all the way to the no-wake zone where the ramp was that we launched from. Within a few hundred yards of the first buoys, the RPM's maxed out and our forward progress stopped. All the symptoms of a spun prop.
I let the RPMS settle back to an idle, and throttled up again. Continued running a short ways, then the same thing. RPMS spiked, speed went to almost zero, and I backed off the throttle. I was sure that pulling this old OMC prop out of retirement was the cause of the problem. The hub was slipping, RPM's spiking, progress stopping. I'd experienced it before and it was happening again. Or so I believed.
By this point, we were close to the no-wake, so I idled it. That's when I heard a clicking noise coming from the engine. Sounded like it was only partly in gear. I reached back and went to neutral, and when I did, it died. And then, the sight and smell of smoke.
Holy crap. I looked down through the darkness and shined a light. The lower unit was wrapped with weeds. They'd caused my prop to ventilate and blocked the water intake. I was so sure it was a spun prop that I never thought to look at the telltale. And now, it was on fire. I didn't dare remove the cowl. I was afraid the sudden influx of oxygen might actually produce flames. I was sure that the engine was toast.
I was sick. I found this Johnson last year and only paid $300 for it. Compression on both cylinders was in the 140's when I first got it. I was fully convinced that I'd just turned it into a paperweight.
I fired up the Hangkai, which I always bring with me on long trips as a "get me home motor", and made our way through the no-wake zone to the boat ramp. Needless to say, it was a long, quiet trip home.
The next day, I began the autopsy. Compression had gone from 140 when I bought it all the way down to 85. I pulled the cylinder head first, which looked OK, and the exhaust covers in order to get a look at the rings. The rings weren't stuck, but there was some scoring and aluminum deposits on the inside of the cylinder walls.
I started reading about fixing it...the "right" way is to have the cylinders re-bored professionally and new rings installed. This involves removing the crank, pulling the pistons, and taking the block to a shop. There's a "poor man's" version: ball-honing the cylinder walls. That would still require removing and opening up the powerhead and removing the pistons.
I didn't really want to do either one.
Then I started wondering what would happen if I just decided to run it as it is. Since that incident, I bought a Johnson 6 and found that it runs quite well with 75 PSI compression. Starts easy and pulls strong. It would be a crapshoot as to whether or not the motor would work correctly, but low risk since the motor was basically a write-off as far as I knew. If it ran well, great! It would cost me some time and the price of a few gaskets. If it didn't, then I'd have to pull it apart, replace the rings, and do a ball hone on the cylinders, which I had initially considered doing anyway. The motor was just too old to take to a shop and have the cylinders rebored. Worst case scenario, if nothing worked, I'd just find a new powerhead.
First step was to bolt the exhaust covers back on. New gaskets in place, I tightened them down. Problem was, they were just a little...warped.
The built-in drinking fountain was an option on the 89 models...
There are some different routes one can take to fix this. Some said to sand it out flat. That would work for the outside cover, but the inside cover has a very large concave area that directs the gasses down the exhaust housing. No bueno. So, I did what any enterprising amateur mechanic would do. I got the hammer.
Specifically, a rubber mallet and some wood blocks, and started pounding and comparing the panels with a straight edge, going a little at a time and using only as much force as was necessary. Finally got everything looking nice and flat, and so I bolted it back together, and...no leaks. Holy cow...the one situation where "Just hit it with a hammer" actually worked.
The overheat, however, had fried my old impeller. It was ugly. Never had one burn up quite like that. And that was what was responsible for most of the smoke and smell, which is great because that's a replaceable item.
I replaced that...and it seemed to barely pump. So, the flushing began...forward through the pickup tube, backward through the thermostat hole, you name it, nothing could get a good water stream coming out of the telltale. And, the cylinder head was getting quite warm.
Turns out, I had two separate issues. One, the thermostat which was in the engine when it overheated obviously got fried. I replaced it with an older one that I kept as a spare and everything started working right, but I still was getting just a trickle from the telltale. And then I found impeller pieces in it. Removed those, and the cooling system started working as intended.
I ran it for around 25 minutes in a barrel and everything seemed OK. I took another compression reading, and it had climbed to 95. That's progress! So, it was time to go to the lake.
I got it in the water and it started easily just like always. Wound her up and...disappointment. I'm used to getting 19-20 mph out of my setup, and now I was only getting around 16. Oh well. It was still better than having to put out a bunch of cash for a new motor or a bunch of parts, or worse, tear the thing down for a rebuild.
But then a funny thing happened. 16 became 17. Then 17 became 18. So, the more I ran it, the more I picked up speed. This is at the end of the first run after the overheat.
18 mph out of a 9.9 in this size boat is nothing to sneeze at. More than good enough considering the circumstances. It will be interesting to see what happens when I have my trolling motor, battery, and other gear loaded, because this boat usually performs better with the front loaded, even if it means more total weight.
In an earlier blog post, I called the Johnson 9.9/15 "the AK47 of outboard motors". I fully stand by that assessment, because I inadvertently put it to the test. I tried to kill it and failed. These things really are nearly indestructible.
Lessons learned:
Cheap insurance.
Due to my own careless bull-headedness, I nearly burned up the Johnson 9.9.
Here's how it went down.
Before July 4th, my wife had a brilliant idea...she wanted to put the boat in at one end of one of the local lakes and go to the other end in order to watch a fireworks show over the dam.
Of course, this meant coming back at night, which was fine. My boat has nav lights and I have a big spotlight. I'd put the wife up front and she could watch for hazards, and I would have a pre-made path on the GPS so that I could stay right in the channel and avoid shallow spots.
Let me preface this by saying I was messing around with some props to see if I could find a better combo for running with a passenger. So, I dug out an old 8 pitch prop to hopefully give the old Johnson a little bit more oomph and RPMS with another person along.
When I say old, I mean, it was the prop that came with the motor. It is likely this thing has been on the motor for decades. It was beat up, scuffed, and had some chips out of it. I took a Dremel and did a little filing to hopefully make it a bit more efficient, then hit it with a coat of black Rustoleum Appliance paint, and it actually looked pretty impressive.
So, with the "new" old prop in place, we set out to go from one end of the lake to the other. We arrived in plenty of time to find a spot, anchor, set up lawn chairs in the bottom of the boat, and relax and watch the fireworks...
On the way back is when our problems began. Actually, we made it almost all the way to the no-wake zone where the ramp was that we launched from. Within a few hundred yards of the first buoys, the RPM's maxed out and our forward progress stopped. All the symptoms of a spun prop.
I let the RPMS settle back to an idle, and throttled up again. Continued running a short ways, then the same thing. RPMS spiked, speed went to almost zero, and I backed off the throttle. I was sure that pulling this old OMC prop out of retirement was the cause of the problem. The hub was slipping, RPM's spiking, progress stopping. I'd experienced it before and it was happening again. Or so I believed.
By this point, we were close to the no-wake, so I idled it. That's when I heard a clicking noise coming from the engine. Sounded like it was only partly in gear. I reached back and went to neutral, and when I did, it died. And then, the sight and smell of smoke.
Holy crap. I looked down through the darkness and shined a light. The lower unit was wrapped with weeds. They'd caused my prop to ventilate and blocked the water intake. I was so sure it was a spun prop that I never thought to look at the telltale. And now, it was on fire. I didn't dare remove the cowl. I was afraid the sudden influx of oxygen might actually produce flames. I was sure that the engine was toast.
I was sick. I found this Johnson last year and only paid $300 for it. Compression on both cylinders was in the 140's when I first got it. I was fully convinced that I'd just turned it into a paperweight.
I fired up the Hangkai, which I always bring with me on long trips as a "get me home motor", and made our way through the no-wake zone to the boat ramp. Needless to say, it was a long, quiet trip home.
The next day, I began the autopsy. Compression had gone from 140 when I bought it all the way down to 85. I pulled the cylinder head first, which looked OK, and the exhaust covers in order to get a look at the rings. The rings weren't stuck, but there was some scoring and aluminum deposits on the inside of the cylinder walls.
I did make one minor modification. In order to get the exhaust covers off, you normally would have to remove the powerhead. I wanted no part of that, so I drilled holes in the side of the lower cowl and opened them up large enough for a socket to fit through. And it worked. I can now get the exhaust covers off easily and with a minimum of fuss. The downside is, holes. But at this point, I considered the engine a parts motor that I was going to try to get running, so the holes aren't really such a big deal.
I didn't really want to do either one.
Then I started wondering what would happen if I just decided to run it as it is. Since that incident, I bought a Johnson 6 and found that it runs quite well with 75 PSI compression. Starts easy and pulls strong. It would be a crapshoot as to whether or not the motor would work correctly, but low risk since the motor was basically a write-off as far as I knew. If it ran well, great! It would cost me some time and the price of a few gaskets. If it didn't, then I'd have to pull it apart, replace the rings, and do a ball hone on the cylinders, which I had initially considered doing anyway. The motor was just too old to take to a shop and have the cylinders rebored. Worst case scenario, if nothing worked, I'd just find a new powerhead.
First step was to bolt the exhaust covers back on. New gaskets in place, I tightened them down. Problem was, they were just a little...warped.
The built-in drinking fountain was an option on the 89 models...
There are some different routes one can take to fix this. Some said to sand it out flat. That would work for the outside cover, but the inside cover has a very large concave area that directs the gasses down the exhaust housing. No bueno. So, I did what any enterprising amateur mechanic would do. I got the hammer.
Specifically, a rubber mallet and some wood blocks, and started pounding and comparing the panels with a straight edge, going a little at a time and using only as much force as was necessary. Finally got everything looking nice and flat, and so I bolted it back together, and...no leaks. Holy cow...the one situation where "Just hit it with a hammer" actually worked.
The overheat, however, had fried my old impeller. It was ugly. Never had one burn up quite like that. And that was what was responsible for most of the smoke and smell, which is great because that's a replaceable item.
I replaced that...and it seemed to barely pump. So, the flushing began...forward through the pickup tube, backward through the thermostat hole, you name it, nothing could get a good water stream coming out of the telltale. And, the cylinder head was getting quite warm.
Turns out, I had two separate issues. One, the thermostat which was in the engine when it overheated obviously got fried. I replaced it with an older one that I kept as a spare and everything started working right, but I still was getting just a trickle from the telltale. And then I found impeller pieces in it. Removed those, and the cooling system started working as intended.
I ran it for around 25 minutes in a barrel and everything seemed OK. I took another compression reading, and it had climbed to 95. That's progress! So, it was time to go to the lake.
I got it in the water and it started easily just like always. Wound her up and...disappointment. I'm used to getting 19-20 mph out of my setup, and now I was only getting around 16. Oh well. It was still better than having to put out a bunch of cash for a new motor or a bunch of parts, or worse, tear the thing down for a rebuild.
But then a funny thing happened. 16 became 17. Then 17 became 18. So, the more I ran it, the more I picked up speed. This is at the end of the first run after the overheat.
18 mph out of a 9.9 in this size boat is nothing to sneeze at. More than good enough considering the circumstances. It will be interesting to see what happens when I have my trolling motor, battery, and other gear loaded, because this boat usually performs better with the front loaded, even if it means more total weight.
In an earlier blog post, I called the Johnson 9.9/15 "the AK47 of outboard motors". I fully stand by that assessment, because I inadvertently put it to the test. I tried to kill it and failed. These things really are nearly indestructible.
Lessons learned:
- Watch your telltale. Yes, it's annoying to keep looking back, but it beats the alternative. It's there for a reason!
- When something goes wrong, don't automatically assume you know what it is. My hard-headedness and refusal to believe that I could be wrong about it being a spun prop led me to keep making the situation worse by trying to "power through it." Reducing RPMS until I found what I thought was the slip threshold would have worked with a spun prop, but made the overheat worse since I really needed to shut it off and deal with the blockage. Had I investigated all possibilities, rather than assuming that I knew what I was doing, this never would have happened.
- And perhaps the most important, and one by which I will always abide from now on...anything unusual happens, the motor comes up and I take a look.
Cheap insurance.
