WARNING: because I have tried a few things to get this engine running well already, this will be a long post, as I intend to fully describe everything I have observed and tried to date. I'm posting now because I don't know what to try next. Apologies in advance for the length of post.
I've got a 1989 8HP Merc outboard that's been in storage for 2-3 years. I've never used it myself because it came with a property that I bought (along with a small boat). However, in the first year I had it, a neighbour borrowed it to use as a kicker for his riverboat (I'm in salmon country, northwest BC Canada) and he reported when he brought it back that it worked great. Since then, it sat in storage until a few days ago when I decided to try to get it up and running to get my small boat on the water.
Before I continue, here's a bit of a disclaimer. I'm a university-educated fellow with no practical mechanical experience. However, I love to get my hands dirty and take things apart to try to fix them myself rather than take them into a shop where a) it'll cost me a bunch of money, and b) I don't learn anything. I have no issues taking things in to get fixed professionally if the problem is absolutely beyond my capabilities, but if it's an easy fix I would rather spend the time to learn how to do it myself. With this in mind, I found a copy of a Mercury Service Manual for 6/8/9.9/10/15 outboards for years 1986 and up.
First things first, I got myself a barrel, filled it with water, and mounted the engine onto it. I knew the gas was old so I disposed of what was in the tank, mixed up a fresh batch of 50:1, and also used the ball pump and depressed the gas outlet on the end of the line to make sure all the old gas was bled out of the line before attaching it to the engine. I gave everything a quick visual inspection and all looked fine, so I made sure she was in neutral, switch set to 'run', primed and pulled out the choke, and yanked the cord a few times. She started up after 5 pulls or so and ran for approximately 5 minutes with a fair amount of smoke. In this time, I was extremely pleased, and put her in forward and reverse to make sure all was well (it was), and just as I was getting ready to shut it off thinking to myself "great, it's running fine!" it started to sputter a bit and run rougher and rougher until she quit. I proceeded to try to get it started up again over the course of a few hours for the rest of the day with no luck at all.
After consulting some webpages, I realized that while the engine was running there was no water coming out of the tell-tale hole. I returned to the engine the next day and tried to get her started up again, and she did start, but again only ran for about a minute before shutting down and not being able to get it running again. There was a bit of smoke and some small amount of water coming out of the tell-tale this time.
At this point I thought there must be a problem with the water pump, so I decided to try to have a look at that. I dropped the lower unit and immediately noticed that the rubber seal with the tube coming up from the impeller housing was messed up, as it was half pushed out of the metal housing. I managed to get it set properly back into place and I thought for sure that must've been the problem. Just to be sure though I still took apart the pump cover to inspect the impeller and make sure there were no clogs or debris in there. The impeller looked fine, although I was (and still am) weirded out by the fact that the Service Manual indicates that underneath the pump cover there should be two nylon washers on either side of the impeller on the shaft. There were NO nylon washers in my assembly. Is it possible that these somehow deteriorated and broke? The key and everything else was still intact so the impeller would defintiely still spin with the shaft, so I didn't think the lack of washers was that huge of a deal, so I put it all back together and figured it would work now because I had reseated that rubber seal with the tube coming out of the pump cover.
Unfortunately, no such luck. I got her started again and there was definitely more water coming out of the tell-tale this time, but it was still only in spurts rather than a continuous flow. Also, in the short time (about 2 minutes) that the engine was running, the water coming out of the hole in fits and spurts went from the temp of the water in the barrel (cool) to lukewarm to HOT (almost scalding my hand). At this point, strangely, the flow of water coming out of the hole increased significantly and became a continuous flow. I'm not sure, but I'm starting to get the impression that perhaps the tell-tale flow is dictated by some kind of thermostat so that it's actually normal to only be fits and spurts until it gets hot, after which it fully activates to continuous flow. I'd appreciate confirmation of this though.
I also need to note at this time that the only reason I'm getting the engine to run at all at this point is because I've figured out that I can pull up a bit on the carburetor cam follower. If I don't pull up on this at all, the engine won't turn over at all. If I pull up on it to open it up, it starts and runs no problem, and if I let go of the cam follower to release it to its natural state, the engine just idles down and dies.
At this point I'm not sure what to do. The engine seemed to be working fine at first until it crapped out for seemingly no reason after 5 minutes, after which i thought the problem had to do with the water pump. After fixing that seal, though, I think the water pump is working fine (especially if I'm right about the flow not being continuous until the temp reaches a certain level). Any help on what my next steps should be would be greatly appreciated.
I've got a 1989 8HP Merc outboard that's been in storage for 2-3 years. I've never used it myself because it came with a property that I bought (along with a small boat). However, in the first year I had it, a neighbour borrowed it to use as a kicker for his riverboat (I'm in salmon country, northwest BC Canada) and he reported when he brought it back that it worked great. Since then, it sat in storage until a few days ago when I decided to try to get it up and running to get my small boat on the water.
Before I continue, here's a bit of a disclaimer. I'm a university-educated fellow with no practical mechanical experience. However, I love to get my hands dirty and take things apart to try to fix them myself rather than take them into a shop where a) it'll cost me a bunch of money, and b) I don't learn anything. I have no issues taking things in to get fixed professionally if the problem is absolutely beyond my capabilities, but if it's an easy fix I would rather spend the time to learn how to do it myself. With this in mind, I found a copy of a Mercury Service Manual for 6/8/9.9/10/15 outboards for years 1986 and up.
First things first, I got myself a barrel, filled it with water, and mounted the engine onto it. I knew the gas was old so I disposed of what was in the tank, mixed up a fresh batch of 50:1, and also used the ball pump and depressed the gas outlet on the end of the line to make sure all the old gas was bled out of the line before attaching it to the engine. I gave everything a quick visual inspection and all looked fine, so I made sure she was in neutral, switch set to 'run', primed and pulled out the choke, and yanked the cord a few times. She started up after 5 pulls or so and ran for approximately 5 minutes with a fair amount of smoke. In this time, I was extremely pleased, and put her in forward and reverse to make sure all was well (it was), and just as I was getting ready to shut it off thinking to myself "great, it's running fine!" it started to sputter a bit and run rougher and rougher until she quit. I proceeded to try to get it started up again over the course of a few hours for the rest of the day with no luck at all.
After consulting some webpages, I realized that while the engine was running there was no water coming out of the tell-tale hole. I returned to the engine the next day and tried to get her started up again, and she did start, but again only ran for about a minute before shutting down and not being able to get it running again. There was a bit of smoke and some small amount of water coming out of the tell-tale this time.
At this point I thought there must be a problem with the water pump, so I decided to try to have a look at that. I dropped the lower unit and immediately noticed that the rubber seal with the tube coming up from the impeller housing was messed up, as it was half pushed out of the metal housing. I managed to get it set properly back into place and I thought for sure that must've been the problem. Just to be sure though I still took apart the pump cover to inspect the impeller and make sure there were no clogs or debris in there. The impeller looked fine, although I was (and still am) weirded out by the fact that the Service Manual indicates that underneath the pump cover there should be two nylon washers on either side of the impeller on the shaft. There were NO nylon washers in my assembly. Is it possible that these somehow deteriorated and broke? The key and everything else was still intact so the impeller would defintiely still spin with the shaft, so I didn't think the lack of washers was that huge of a deal, so I put it all back together and figured it would work now because I had reseated that rubber seal with the tube coming out of the pump cover.
Unfortunately, no such luck. I got her started again and there was definitely more water coming out of the tell-tale this time, but it was still only in spurts rather than a continuous flow. Also, in the short time (about 2 minutes) that the engine was running, the water coming out of the hole in fits and spurts went from the temp of the water in the barrel (cool) to lukewarm to HOT (almost scalding my hand). At this point, strangely, the flow of water coming out of the hole increased significantly and became a continuous flow. I'm not sure, but I'm starting to get the impression that perhaps the tell-tale flow is dictated by some kind of thermostat so that it's actually normal to only be fits and spurts until it gets hot, after which it fully activates to continuous flow. I'd appreciate confirmation of this though.
I also need to note at this time that the only reason I'm getting the engine to run at all at this point is because I've figured out that I can pull up a bit on the carburetor cam follower. If I don't pull up on this at all, the engine won't turn over at all. If I pull up on it to open it up, it starts and runs no problem, and if I let go of the cam follower to release it to its natural state, the engine just idles down and dies.
At this point I'm not sure what to do. The engine seemed to be working fine at first until it crapped out for seemingly no reason after 5 minutes, after which i thought the problem had to do with the water pump. After fixing that seal, though, I think the water pump is working fine (especially if I'm right about the flow not being continuous until the temp reaches a certain level). Any help on what my next steps should be would be greatly appreciated.