5hp Nissan, 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 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 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

 

[Sea Rider]

Re: 5hp Nissan, no water at Idle

Run a wire soaked in vinegar up the pee hole, maybe is light obstructed. No need to wait to start the engine, just lower leg and start it inmediately. Check impeller if still no peeing at all at idle. Don't expect to much pee pressure at idle on that little motor, betters when reving.

Happy Boating

 

[pvanv]

Re: 5hp Nissan, no water at Idle

Yep, fine to start as soon as the pickup is submerged. Pump inlet fills immediately. You may have a marginal impeller/housing cup, (probably) or some obstruction in the telltale (maybe).

In the future, when doing service to the pump, replace the entire kit, which includes the cup and wear plate. The side clearances on these is very important, and often overlooked. Replacing only the impeller is inviting premature impeller wear.

Full info is in the Factory service manual, available from any dealer (including me); The wp work is very straightforward on these, and includes the drive shaft (don't get grease on the very end of the shaft, or it may not seat fully in the crank), as well as the shift coupler and water tube.

 

[Sea Rider]

Re: 5hp Nissan, no water at Idle

If remember well, that engine has a rubber hose protuding out of the head, ideal would be to remove hose from head and then run a wire up the water passage, do so on the small 3.5 as clearing just the hose won't help much. Most of the time salt/debris obstructions are located inside small exiting pee hole passage, prior connecting to the rubber hose.

Happy Boating

 

[pvanv]

Re: 5hp Nissan, no water at Idle

Nope, no hose on those. Just a port in the bottom of the block, near the flushing plug. The do clog with junk from time to time.

 

[C Jones]

Re: 5hp Nissan, no water at Idle

Thanks everyone for all the help.
I went to my marina today and stuck a piece of coat hanger in the exit hole
After 3-4 times I started the engine with the choke pulled and it peed fine
I idled it down after reaching temperature and it peed at idle.
With it running and warm I ran the wire in 8-10 times and it still pee's fine at idle
I don't think it has the same good flow as before but it was hard to tell with it being very windy today.
Some one at my marina stopped by and suggested I put 2 gallons of vinegar in a bucket with 2 gallons of water and try to wash/ clean it out that way.
Is this ok to do?
Leaning over the back of the boat I tryed to find the water inlet. I didn't find it.
My thinking is water has to come in to be pumped so it needs cleaning as well.
Can someone describe the inlet for me, upside down hanging out the back of the boat was not the best position for clear thinking. Thanks again Charles

 

[Sea Rider]

Re: 5hp Nissan, no water at Idle

Water inlet/strainer is located at bottom tail under cav plate, if salt water has formed salt layers/crusts inside water passages, don't think that placing a bucket with water and vinegar will help that much, probably will need to spend 1 full day to clear. Better is to run a longer thinner wire soaked in vinegar through pee hole upwards head several times. As said before, don't expect a thick water jet from pee hole at idle, jet will improve when reaching higher revs. This is normal behaviour on this small engine.

Happy Boating

 

[pvanv]

Re: 5hp Nissan, no water at Idle

Thanks everyone for all the help.
I went to my marina today and stuck a piece of coat hanger in the exit hole
After 3-4 times I started the engine with the choke pulled and it peed fine
I idled it down after reaching temperature and it peed at idle.
With it running and warm I ran the wire in 8-10 times and it still pee's fine at idle
I don't think it has the same good flow as before but it was hard to tell with it being very windy today.
Some one at my marina stopped by and suggested I put 2 gallons of vinegar in a bucket with 2 gallons of water and try to wash/ clean it out that way.
Is this ok to do?
Leaning over the back of the boat I tryed to find the water inlet. I didn't find it.
My thinking is water has to come in to be pumped so it needs cleaning as well.
Can someone describe the inlet for me, upside down hanging out the back of the boat was not the best position for clear thinking. Thanks again Charles

In our shop, we push the wire in while the motor is running. That way, the water pressure helps to blow out any debris.

 

[C Jones]

Re: 5hp Nissan, no water at Idle

Thanks Sea Rider and Paul,
I just rounded up several smaller wires to poke farther up the the hole.
I,ll try and check the inlet/ strainer as well today. Charles

 

[Sea Rider]

Re: 5hp Nissan, no water at Idle

If needed dismount the lower strainer and check that all tiny holes are free from any obstruction, this can cause impeller to pump a lesser water intake flow to all water passages. For the record, let us know what was the issue found.

Happy Boating

 

[C Jones]

Re: 5hp Nissan, no water at Idle

Wednesday of this week I ran a smaller wire into the tell/tale hole.
It seemed to go in about 3"
I repeated this several times and started the engine and did it several times running
No wind today and after repeating Wednesdays wire prodding it seems just as good as it was before this started.
Good flow at idle.
I assume a bug or some debris was clogging it.
I poked the wire into the inlet several times as well.
Thanks everyone for all your help and and advice, Charles