NS 9.9b cooling water check port

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Uncle Krusty

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1993 Nissan NS 9.9b2. This is a new-to-me motor and today I put the muffs on and fired it up. But only briefly because there was no telltale squirt. The owner's manual I have says it's on the starboard side of the motor. My manual is from 2007, so the motor has probably changed since '93. The only thing I see looks more like a corroded Allen fitting, which is located at a corner about two inches below the lower engine cover, not where the manual says it is. It's not deep enough for a 2.5mm Allen key to get a grip, and I can't get a paper clip to penetrate it. There is an opening at the back of the motor, with something like a hood covering it. The paperclip probe went in several inches.

So any idea where I can get an earlier manual, and any clue where that cooling water check port is? Here's the thousand word picture.
 

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That is the proper pee hole as you can see from my NS15B2 (same motor) and I'm guessing your motor has spent quite a bit of time in saltwater.
Crusty for Krusty?


https://drive.google.com/file/d/1M-lruc7Wd875Hiv8KP5OkCM9ypUMbS9g/view
 

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Yup, it's crusty. Came from the Oregon coast. So, drill it out? Wonder what the motor looks like on the inside. I may be about to get an expensive lesson.
How is your motor treating you?
 
In my experience, if/when running well, the Nissans are the best made & most reliable running OB motors ever made! Maintaining a fleet of small boats at my boatclub for 40+ years I have yet to ever replace a coil, CDI ignition, plug wire, power pack or anything else. The only thing I’ve ever put on them are the typical plugs, thermostats & waterpump/impeller (standard service items) for any Nissan motor. I think I’ve only ever had to sync&link tune 1 at that.

You could follow the hose down from inside & maybe remove it before you drill it out, not sure how much room you might have to maneuver in there.
 
Uncle Krusty said:
Thanks Dale. I don't see a hose anywhere near that area. If I drill it how do I not get shavings in the cooling system?
A small drill by hand should do it, twisting the drill in your fingers or with a pair of locking pliers. Also flush chips & port with a squirt bottle filled with warm/hot water.
 
OK, thanks. I was going to use a small bit on a cordless drill and go lightly. I'll try it by hand first, but it's clogged pretty tight. I'll let you know how it goes.
 
I've made it in about a quarter inch, using my cordless drill verrry slowly. How far do I need to go and I'm wondering if there is a 90 in there? What is coming out looks a little like concrete. I'm going to stop for now, awaiting your wisdom. Either that or take it to someone who knows what they're doing. In the meantime, I fish from the bank, dangit.
 
Most likely it is a dirt dobber nest. If by any chance you have a chuck off an old drill you can put a bit in it and turn it by hand and while turning it flood it with a water hose and it will usually come right out doing it that way.
 
I wish it were dirt daubers, but this stuff is hard and it's not mud coming out, it's gray and grainy. I'm thinking it's aluminum oxide and it's been there a long time. Not a good sign at all.
 
Uncle Krusty said:
I'm thinking it's aluminum oxide and it's been there a long time.
Well I have to admit I have never had to unplug the pee port (Nissan calls it the 'check port') or overboard water indicator port of any Nissan OB oer the years (all saltwater motors too). And where most other OBs I work on have a visible rubber hose existing the block to an exit plug on the bottom of the OB pan or side cover (mostly on the back rear-right of the motor as it faces AWAY from you), those Nissans have it exit from down the power leg.

I am no where near my motor right now and I just reviewed the Parts and Service manuals I have for my Nissan 18hp and for the life of me they don't show how water exits the block. Perhaps on the Nissans it is via a metal water tube direct from the block and not that of an added rubber tube? But see the detail I added at the end of all this rambling ...

What you could do - Sounds like this was a saltwater OB. First, I'd keep trying a stiff piece of piano or spring wire, cutting a 45-degree angle on the tip end and keep twisting it in that port. Likely that is calcified salt and/or sand you're seeing and not Al-O2.

Second, look for any rubber hose or such exiting the block and routing down the powerleg on that right-rear side as you stand behind the motor. You might not be able to get your hand or tool all the way down, but you might be able to confirm how cooling water exits that powerhead. On more than a few OBs I have worked on, when I was able to remove a rubber hose from the block, it was that junction from the block to the hose that was blocked. The threaded hole in the block is a tapered pipe thread, maybe 5/16" or bigger, but then they thread a metal or plastic fitting into the block to attach the 1/4" or less tube, so that junction right there serve as a restriction or place where build-up can collect.

That OB must have a thermostat on it. You could buy replacement gasket and t-stat (to be sure for operation) from www.marineengine.com or other source. Pop off the t-stat cover and assess the internal condition of the water passages. On one 6hp OMC I worked on that was overheating, the head was full of salt. I pulled the lower unit off, turned the OB upside-down and filled the water pipe with white vinegar to fill the head and I left it that way for a few days. I saved the vinegar and turned it back over and reassembled, running it in the smallest bucket/tub I could find where I had 2-gallons of vinegar to the rest water, hoping to further flush out and dissolve any salt. Well ... it fixed it!

But I would ONLY do this after replacing with a new thermostat. Maybe you could fill 'whatever down-pipe' routes to the pee port with vinegar, maybe that would help dissolve the build-up. But NOTE vinegar needs to be flushed out and rinsed with freshwater, so be prepared to tip her upside-down a few times to rinse it well (if you can't unclog it this way).

On small OBs, the thermostat stays closed to keep the powerhead warm for easier idling. Typically whilst running a small motor it should take a few minutes to open up the thermostat, but at ~5-minutes or so it could overheat, if not cooling. So you can do a check, but be fast about it. Feel the water exiting or spitting out the exhaust relief ports on the back of the motor, centered and a few inches down from the pee hole as the other poster's pictures show. My Nissan manual (covers 2.5 to 40hp motors) says that model OB uses a 125-deg F t-stat, so the water might be very warm to hot, but not so HOT that you can't keep your hand in the stream.

They also make 'temple-stiks' that melt at a certain temperature and these can be used to assess heat on the powerhead, but you should be able to hold your hand briefly above the plugs or side of block on any p'head that is being properly cooled, but not on one overheating. CLEARLY be safe here and if any of this is beyond your capabilities, then you gotta get a pro. But try some more snaking with a sharpened wire ... I think this is your best option!

(On my 18hp, prior to powerhead removal the OEM manual does state "Disconnect pilot water hose from exhaust cover.", which for my model implies a rubber hose routes dwon from the block to the back of that powerleg, where one sees the pee port exit. Not sure of your model ... and no pictures are provided.)
 
It's well and truly plugged. I've used a straightened paper clip and will try putting an angle on it, but if the drill won't clear it... There is a picture on my OP. Is there something else you need to see? I don't think I'm competent to drop the section below the PH. I'll look at it in the service manual, but I think I'll end up taking it to a pro. They are about three weeks out. There is no plastic that I can see. How deep do you think I'll need to go in?
 
Uncle Krusty said:
How deep do you think I'll need to go in?
Well not the answer you want ... but deep enough!

I'll be heading to my boat tonight and plan to head out to a sandbar with the dog. I'll check out my cooling water overflow and will advise as my parts (pee port hole and exhaust relief ports) on my 18 are located at the same spots as your 9.9. I'll put a spring wire up her pee port to give her a good colonoscopy and we'll see what I find ... like even if it is a 'straight shot up for X many inches'.
 
Uncle Krusty said:
That would be great ! Thanks.
Well, I have some answers for you. I can get a sharp spring wire about 2“ up inside my ‘water check port’ hole. it appears to be a hard pipe passage from the bottom of the block down to this exit.

I don’t have a good signal enough tonight to upload photos to this post, but follow the round tube centered on the rear of the powerhead head that goes from the thermostat pocket and then straight down. I think that might be the cooling passage.

Again, that makes me think that perhaps if you pulled the T-Stat cover and filled up the passage with white vinegar, perhaps you could dissolve some stuff from the top, while you work the spring in from below.

Once you get 2” in, try a thinner/lighter spring wire, as it must take a turn and I had a heavy wire (0.050”, almost to 1/16” diameter). Maybe some brass wire from a hardware store would be great, as it is not as hard as metal and it should take any corner. Twist it round & round as you go.
 
Pictures from the rear of the motor showing the heavy 0.050" spring wire into the hole and the amount traveled.

Other photos show the central water tube, integral to the powerhead, coming down from the thermostat on this 18hp Nissan.
....
Nissan1.jpg

Nissan2.jpg

Nissan3.jpg

Nissan4.jpg
 
Hey Dale, thank you for the incredibly detailed and knowledgable responses. I apologize for taking so long to return to this thread, life got in the way. I have a mobile marine guy coming out today to fix this and look the motor over. This might be good info for him. I'll let you know what he finds and how he fixed it. (If he does.)
 
Well, I had a mobile marine mechanic to the house to look at it. He had no clue, only charged me $20. The shops around here are 3-4 weeks out. I took another shot at it per your suggestions. I got nowhere, using a good sized really stiff wire. So it's off to the shop. I'll report in about 3weeks. Probably about the time the bass quit biting.
 

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