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Old 16-09-2010, 16:48   #1
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Can I Run Outboard without Water Pump for a Few Minutes ?

I understand that water is needed to cool the engine and running it without water will cause permanent damage. But my primary use for the outboard right now is to get my dinghy to the mooring ball where my sailboat is tied. So I really only need to run the outboard for a few minutes. Rowing isn't an option because the sailboat is on a river and it's almost impossible to row against the current. The engine starts out cold and the oil is cold--will that keep the engine cool for a few minutes?

Looking through the service manual, it looks like getting to the water pump isn't that easy. First step is to drain gear oil. And, since the season is almost over, I'd prefer to do all this later rather than having to bring the outboard home, work on it, replace the gear oil etc. I already purchased the repair kit with a new impeller but haven't installed it. How much damage do I cause by running the engine for very brief periods of time without water?

Also, a few questions about working on the engine: First, do I have to buy the Nissan spring pin tool as the manual recommends, or is there some more common tool that I can use that I may already have? Second, where is the thermostat? The manual says to check it, but doesn't say where it is. The problem could be the thermostat and not the impeller. As you can tell, I haven't worked on this part of the engine before.
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Old 16-09-2010, 18:15   #2
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My dad ruined the outboard on his bass boat by running it out of the water. I've seen people start them up out of the water just to show that they start, but beyond that I think you're (almost literally) playing with fire.
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Old 16-09-2010, 18:30   #3
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Fix it....it doesn't take that long.

You can replace the impeller with common wrenches.

Oil is not expensive
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Old 16-09-2010, 18:49   #4
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And, since the season is almost over, I'd prefer to do all this later rather than having to bring the outboard home, work on it, replace the gear oil etc.

How much damage do I cause by running the engine for very brief periods of time without water?


I already purchased the repair kit with a new impeller but haven't installed it.

I reread your post a few times before I got it. I assumed you wanted to go to your boat "once" to do the repairs. Now I realize you want to use the engine until the end of the season before doing the repairs.

Fix it. You could be extremely sorry if you don't. Even 3-5 minutes under load could trash the engine.

You probably don't need any special tools.
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Old 16-09-2010, 18:56   #5
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Ok sounds like I should try to fix it. Is the problem definitely the impeller/water pump or could it be something else? What happens is that when I first start the engine, there'll be a good flow coming out of the little pee hole for several seconds. Then it'll slow to a trickle. Then it'll stop completely.
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Old 16-09-2010, 19:05   #6
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is this a little 3.5 hp Nissan? If so, it's possible that the telltale (sorry, but I can't bring myself to call it a "pee hole") is clogged. Run a pipe cleaner up it a few times to test it.

If you do have that Nissan 3.5, changing the impeller is a very simple, very quick job.
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Old 16-09-2010, 19:27   #7
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If there is a little brass center in the impeller. it has probably broken loose drom the rubber.
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Old 16-09-2010, 19:50   #8
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Sounds like it could be sucking something up and getting blocked. I had that happen before. It was a piece of soft rubber (not a piece of the impeller). I could see it through the water intake holes when the motor was out of the water. I pulled it out through an intake hole with tweezers or hemostats, can't remember which.
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Old 16-09-2010, 20:00   #9
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the impeller is a round donut with fins on it, as it spins it moves cool water through the engine to keep it cool......if you start the engine without it being in the water for ONE SECOND you are asking for impeller problems.

what happens is the little fins break off because there is no water to lubricate the impeller....... at the bottom of the shaft were the prop is, should be the water intake, if you look there you may find peices of your impeller.

you should always have a stream coming from that pee hole
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Old 16-09-2010, 20:03   #10
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Well definitely intermittent blockage.

The question is whether it is something external to the engine or internal. It could be external. Or more likely it is one or more impeller pieces as it comes apart.

One sure way to find out is do the maintenance.

What you will find out Joe is that the impeller is a consumable of sorts. It's designed to fail and be replaced. The job won't be that hard to do.
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Old 16-09-2010, 20:24   #11
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Quote:
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is this a little 3.5 hp Nissan? If so, it's possible that the telltale (sorry, but I can't bring myself to call it a "pee hole") is clogged. Run a pipe cleaner up it a few times to test it.
This is a good place to start with many outboards. Pipe cleaner sounds a little... wussy for most of them.

A dockmate kept taking his 60HP merc into the shop before he learned this trick.

Might try a zip tie up the... pee hole. Spin it in your fingers and see it it knocks something loose.
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Old 16-09-2010, 22:37   #12
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Old 17-09-2010, 00:37   #13
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This is actually pretty common. Mud daubers built a nest in my dad's Tohatsu 50 pisser.
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Old 17-09-2010, 05:20   #14
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If your engine is more than two or three years old without changing the impeller then its probably time anyway...I'd start there and do the gear oil at the same time.... may save you being stuck somewhere later.... Also not very likely that the impeller sucked something up that was small enough to go through the impeller but too big get through the rest of the cooling system... It is designed to prevent things going in there that may cause a blockage....
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Old 17-09-2010, 06:20   #15
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Quote:
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I'd prefer to do all this later rather than having to bring the outboard home, work on it, replace the gear oil etc. I already purchased the repair kit with a new impeller but haven't installed it.
This is a pretty easy job with a small saw horse and a dish pan. As long as it doesn't get you in trouble with whoever manages the place you keep your dinghy you should be able to do it right there in half an hour.
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