Nissan 5hp, no water at idle

[C Jones]

2002 Nissan 5hp 4stroke long shaft, I start the engine at least once a week, year round on my h23 Hunter in my slip.
I keep the engine raised to the first stop with the prop just out of the water.
The engine always has a moter cover on it in the slip.
Today I lowered the engine into the water, pulled the choke a little and it started first pull as usual.
As it was idled up with the choke it was fine, water squirting out the back top starboard side of the engine.
When it had warmed up in 2 minutes I pushed the choke in and it idled fine.
Thats when I noticed no more water squirting out at idle.
I revved it up and water squirted out, at idle no water.
I had the engine serviced July 2009 at a Nissan dealer and that included a new impeller.
I only run the engine less than 10 minutes or less getting out of my slip and onto the lake until my sails are up and I turn the moter off and raise it until I return and run it 10 minutes or less back into my slip.
I am going to replace the impeller.
My question is should I wait 5 minutes after lowering my engine to start it?
Does the lower unit take some time to fill with water when dry?
By lowering it and starting it immediately, am I running the impeller dry for a few seconds?
My best guess on run time for the year is less than 20 hours.
I have changed impellers on several outboards over the years but not this engine.
Any tips? I assume I have to disconnect the shift linkage in the service hole, align the water tube, drive shaft and linkage at the same time after the impeller is installed with grease on it going back together. Thanks Charles

 

[Capn John]

Try slipping a wire up into the water discharge hole to clean out any debris that may have collected. Given everything else you've said, chances are everything is fine, you just need to clean it out to see the water start streaming.

 

[C Jones]

Thanks Capn John, I will try that tomorrow and post the results

 

[Don12364]

Only a small proportion of the total cooling water usually comes from the tell tale hole. It seems likely that there is water in the main cooling system but not quite enough to spray out of the small hole.
Alternatively your impeller might not generate much flow at idle revs.

So your plan to replace it is good but if that doesn't solve the issue then it is probably the former reason. Anyway you will have a spare impeller for next time.

 

[C Jones]

I went to the marina today and ran a piece of coat hanger in the tell tale hole.
After several times I started the moter and after it warmed up I idled it down
I have water out the tell tale hole at Idle now.
I ran the rpm's up and continued to run the wire in and out for 10 minutes
with the moter running.
It does not seem to have the flow at idle that it had before but it was very windy and hard to tell for sure.
A friend stopped by and suggested I run the engine at low rpm's in a 5gallon bucket with 2 gallons of vinegar and 2 gallons of water.
He suggested this would clean the entire system
Whats everyones thoughts on that?
I tried to find the water inlet on the lower unit but leaning out that far I didn't find it for fear of falling in the cold water.
My thinking is water has to get in before it can be pumped out so clean the inlet as well
I'll take care of that on a less windy day

 

[Capn John]

I wouldn't recommend running vinegar thru your cooling system, but by all means make sure the inlet is not partially blocked with something.

A coat hanger is probably too stiff to run very far into the discharge hole. I'd recommend using a piece of electrical wire that will have the flexibility to bend more and go back further into the overflow passage. You're getting some flow now after using the coat hanger where you had none before at idle. Get the wire a little deeper than the coat hanger is going and you can probably clean it out more.

Good luck!

 

[Pops]

I had this problem on a Yamaha outboard. I would clean it every time before I started it (probably didn't need it every time, but I got into the habit). I used a 18 inch piece of weed wacker line, the heavier stuff. I had it fastened on the starting key ring. Every time I went to start the motor, there would be that line reminding me to ream that sucker out. My problem was bugs attracted to the moisture in that pee hole.

 

[C Jones]

Thanks everyone, I,ll try the smaller wire and weed eater line as soon as I can.

 

[mel22]

Sounds like you are making progress, good for you. I'm not sure about the vinagar as Capt John says, but maybe you could check out some of the engine flushes at the auto stores. Might be good to idea to check this idea with engine manufacture first as it could be hard on impeller.
keep posting your results as will be sure to help others.

 

[mel22]

I just spent some time researching the automotive coolant flush, Now I'm sure I would't do that. Woody wax makes a product but outboard manufactures continue to specify plain fresh water.

Still sounds as if you are making headway with your own methods so good luck.

 

[C Jones]

Wednesday I ran a smaller wire, about the size of a bread wrapper wire with no plastic on it into the tell/ tale hole several times.
It seemed to go in about 3"
I then started the engine and repeated this with it warmed up and running.
I just got home from the marina and repeated all of the above. No wind today and I'm happy to report the flow at Idle is as good as it ever was.
I ran the smaller wire into the inlet as well several times with the engine off.
I'm guessing a bug or debris was blocking the hole as I never saw anything come out. Thanks again for your help and advice. Charles

 

[JVB]

Running your outboard without the water intake submerged or supplied with water via a hose and "earmuffs" will make for very short impeller life. Don't do it ! Not for two minutes. Not for two seconds. Without intake water the rubber impeller blades are rubbing on dry metal with nothing for lubrication. The blades have worn or melted down so that they barely touch the housing. That's why it is not pumping as it should at idle. You need a new impeller ASAP. The squirt hole is probably getting plugged by debris from the destroyed impeller blade tips.

"Does the lower unit take some time to fill with water when dry?" No, it will fill to outside water level almost instantly. Then it will take maybe 5 seconds or so for the pump to fill the rest of the cooling passages.