Nissan NS70A - no water from telltale

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Jul 24, 2020
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I just bought a boat with a 1985 Nissan NS70A. The engine runs great, but no water is coming out the telltale hole. I just replaced the impeller and started her up, but again there was no water coming out. I know that the section of tube in the engine leading up to the telltale is not clogged. Is there anything you guys would recommend I do to fix it? Any specific diagnosis steps i should take?
 

pvanv

Admiral
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Apr 20, 2008
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6,500
Use a cheap IR thermometer to check engine temp. If around 150F, you are cooling, and the telltale is plugged.
 

Sea Rider

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Tilt the motor to max, squirt several shots of Carb Cleaner with the provided cannula inside the pee tube, let it soak for at least one hour or more, test again...

Happy Boating
 
Joined
Jul 24, 2020
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Tilt the motor to max, squirt several shots of Carb Cleaner with the provided cannula inside the pee tube, let it soak for at least one hour or more, test again...

Happy Boating

I tried that, but still no luck. When you said to tilt the motor to max, you meant to lift it up all the way, right?

I also don't see water dripping from any other areas that would otherwise lead me to believe that water is running through the motor if that tells you anything.

I haven't tried to run it and measure it with an IR thermometer yet.
 

Sea Rider

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Yep, tilting, lifting up the motor. Does the motor exits water right in middle of the prop when the motor is flushed ON with ear muffs ? When the impeller was changed, assume that installed the key which locks the impeller to the drive shaft ? did the upper water pump's grommet matched well the metal tube that sends water to the powerhead ?

Some Tohatsu motors have a bolt which is a flushing port on their powerheads, check if the exhaust cover has one ? if so will need to buy a flushing adapter to hook a hose there and flush the whole powerhead with motor OFF for some time. Will need to remove the thermo, put the lid back on so when flushing all the water jackets will be exposed and opened for water to re circulate at high pressure...

Happy Boating
 
Last edited:
Joined
Jul 24, 2020
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A little spray of water comes out from the middle of the prop when the engine is on.

I think I installed the key correctly but couldn't find much info on it - i just stuck in into the little slot on the impeller and aligned that with the flat area on the drive shaft. It looked like the water pump connection lined up when i was putting the lower unit back on.

As far as the flushing port, my manual refers to something that might be what you are talking about. It says, "Install the drive cleaner to the cooling water intake. Direct tap water through the drive cleaner while operating at low speed for approximately 10 minutes".

How do i find the "cooling water intake"? Also, how do i find the thermo?
 
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Jul 24, 2020
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Also, do you know where i can buy the drive cleaner? It looks like tohatsu doesn't make it anymore (surprise!)
 

Sea Rider

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That motor is used in fresh or salt water ?

Before going any further, remove the cowl, remove the rubber hose that connects to the upper powerhead, spray bursts of WD-40 or Carb Cleaner spray with the provided cannula while poking deep in the hole, sometimes that area can clog if the motor is used in salt water, not flushed after use while sitting unused for long time periods. Report if worked...

Check if the exhaust cover has a 1/2" bolt, as in pic, if so that's the flushing port, will need to buy a flushing attachment connect a garden hose to it, remove thermo and flush at the highest water pressure available to clean all water circuits well, provided that don't have crusts formations which a water flush won't remove..

Happy Boating
 

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Joined
Jul 24, 2020
Messages
8
That motor is used in fresh or salt water ?

Before going any further, remove the cowl, remove the rubber hose that connects to the upper powerhead, spray bursts of WD-40 or Carb Cleaner spray with the provided cannula while poking deep in the hole, sometimes that area can clog if the motor is used in salt water, not flushed after use while sitting unused for long time periods. Report if worked...

Check if the exhaust cover has a 1/2" bolt, as in pic, if so that's the flushing port, will need to buy a flushing attachment connect a garden hose to it, remove thermo and flush at the highest water pressure available to clean all water circuits well, provided that don't have crusts formations which a water flush won't remove..

Happy Boating

I just bought it, but i assume it was used in salt water. It also hasn't been used for 2 years. I'll try to do what you said when I have free time this Saturday.

I do have a thought that might help to solve the issue: I just got the service manual for the engine, and in the picture of the water pump, the impeller key seems a lot bigger than mine. Mine is a tiny piece of plastic that was barely wider than the slot for it in the impeller, whereas the impeller key in the picture in the manual seems to take up the entire flat area on the side of the drive shaft for the portion of the drive shaft that goes in the impeller. Do you think this can be the issue? Maybe the key is broken or it isn't the original key? If so, is the part available/ can i use a different impeller key? If it's not available, I have a 3d printer that i can use to fabricate a new one, but would need either an stl file for the impeller key, or the dimensions of it so that i can design my own, although I'm not sure where to find those.

Thank you for all your help!!
 
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Sea Rider

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Sep 20, 2008
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You're welcome Jacob,

The key probably is SS and fills almost all the gap of the drive shaft, if the impeller was assembled with a plastic key, that won't work or will pump poor water till the key shreds itself. Better remove the lower leg and have a look, post pics. The original key should be available at any Tohatsu dealer, Paul will surely chime in and lend you a hand...

Happy Boating
 
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