outboard maintenance

[Jeff]

Any of you ever done any work on an outboard motor's lower unit? Yesterday after getting the last of the blisters patched on my catalina 22 I decided to get the motor ready to go. Got rid of the old gas, replaced the spark plug, changed the lower unit oil, replaced pull rope, lubed the turning shaft etc. I stopped short of pulling the lower unit and checking the impeller and water pump. I had a new one put on a year ago in Feb and have only run the motor an estimated 10 - 15 hours since, however it has been sitting for 6 months now and I'm wondering if I should replace it again. Do any of you have experience with this? Is it overly complex. I have no problem tearing into something if its already broken (I figure if I cant fix it then I can pay someone to repair my damage as well as the originally problem), but don't want to get in too deep and break something thats not already broken. If any of you have done this I would like to hear what you think.

 

[Bill4867]

If it ain't broke don't fix it

The lower units of outboards are typically not a high maintenance area. Change the oil in the lower unit befor putting it to bed for the winter, never start the motor dry and if you notice you lower unit oil has a milky color then you have water intrusion and must deal with it. When you open the lower unit to replace the leaky seal, you replace the impeller. For what ever reason outboard impellers seem to hold up for quite a while as long as they are never run dry. If your impeller is starting to fail you should notice a reduce water flow from the piss tube.

 

[Bob B.]

Outboard water pump impeller

Hello Jeff:Bill is right in saying "If it ain't broke don't fix it". Fours years ago I had to replace the lower leg on a 115 HP Mercury, ski boat. (Hit a large rock)I dismantled the propeller shaft, drive shaft & water pump on a used unit to check the bearings & replace the seals. Replaced the water pump impeller even though it looked good. It had a good stream from the "piss tube".Last week the stream was much less than before so installed a new pump even though it looked like new. $63 Canadian. The stream is still not what it should be. At idle speed it is a very weak stream. When reved up, the stream is just OK.There is lots of water coming from the water outlet at the grill just above the anti-cavitation plate so I am not worried about poor cooling. Any body else have this problem?Replacing the pump is not a difficult job. Just be sure to time the gear shifter shaft. You can reach in & mark the shaft & coupler when you lower the unit about 3/8", before you drop it completely. Also bend the impeller lobes in the right direction by turning the driveshaft clockwise while forcing the pump housing down on the impeller. Working on the propeller shaft & drive shaft bearings is more complicated because you need to consider gear mesh/backlash etc.I think the small motors would be similar to large motors.Purchase or better still borrow an overhaul manual before starting any tear down. Regards, Bob B.

 

[Aldo18609]

Just Test It

Jeff: The impeller on my Johnson 6 HP lasted 20 years. It could have lasted even longer, but my wife had some other work done on our motor while I was out of the country on business, and they replaced it when they were replacing the seals to the lower unit.I keep my motor on a wooden stand that I built out of 2 X 4s. I put the lower part into a drywall bucket, (actually 2 drywall buckets nested together with the bottom cut out of the top bucket). This makes a very deep bucket. Anyway, I run my motor in this bucket to test it. This can save a bunch of embarrassment when you launch your boat at the beginning of the season. You can check if your motor pees the way that it is suppose to. If it doesn't, what you do is take a "pipe cleaner" and clean out the fitting where the jet of water is suppose to come out. I do this with the motor running. This really helps, in fact, I keep a pipe cleaner on the motor handle so that it is always ready. I fix and check plenty of things that aren't really broken, especially around my boat, but I wouldn't worry about your water pump impeller unless you ran it dry. And I do recommend the test method that I described above. We even test our little 2 HP dingy motor in a similar manner, but we have to remove the prop for that motor, because it doesn't have a neutral position.You will just feel more comfortable knowing that your motor is ready to go. I don't recommend that you run it very fast in the bucket, especially if you put it into gear. When you run it in neutral, don't run it too fast because motors aren't really meant to run fast without a load on them, at least in my opinion. I keep the bucket full to overflowing with a hose when I am test running it. I put blocks under the bucket to get it to the correct height.Aldo