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Not enough water pressure to cool?

T

tale

New member
I have a 1989 Mariner 100HP 2 stroke that came with the 16' Astroglass that I purchased recently. It had been sitting for about 15 years. I took it on as a project and it has been a lot of fun to restore. I have the engine running good now, but I can't get water to come out of the tell-tale. I have changed the water pump impeller. I have changed the thermostat. I have also blown air through the tell-tale and verified that the tube isn't blocked up to the engine block. I have let it run for about 3 or 4 minutes to the point that I got worried it may overheat, so I shut it off. That was with it in the water at the boat ramp (so the engine was in water up to a normal level).

Today I took the lower unit off and inspected the water pump again. I was hoping it was something simple, like the woodrift key wasn't aligned properly or something. However, everything was as I believe it should be.

So, I decided to take my water hose and put it up to the spot where the lower unit typically connects to pump water up through the engine. After about 20-30 seconds, water started streaming out of the tell-tale. It seemed like there was a lot of pressure that had built up as I pressed the hose up to the intake.

The fact that water was streaming hard out the tell-tale makes me believe that there aren't any obstructions, but I feel that it shouldn't require that much pressure to get it to flow. Also, when I changed the water pump, the impeller was in one piece. I don't believe that there are parts of it that got pushed up into the engine.

I'm not a mechanic, so I'm at a loss as to what could be the problem. Is there something you all would recommend for this issue?
 
Run the lower unit with a drill and see if water shoots out of the pump.

Jeff
 

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faztbullet said:
Make sure you use tool to set slinger height and grommet is in housing to seal water tube.
Click to expand...

I'm not sure what you mean by slinger height and grommet. Could you tell me more?

Here are two videos from today. I hooked up the lower unit to a drill and put it in water. It was pumping good once I put it far enough into the water. The other video is of me putting the hose up to the bottom of the intake to make the water flow through the engine. You can see that it required a lot of pressure from the hose before it came out the tell-tale.

Let me know if you all can't see the videos. They should be public to anyone with the URL.

https://photos.app.goo.gl/gVnwCzNS2bjk4Who8
 
1) The slinger is missing on top of pump...#42, Make sure gasket #28 is new and grommet's in place in both ends of #32

wp.JPG
 
This is exploded diagram for this engine. What number would the slinger be?
https://www.boats.net/catalog/mercu...hru-0d283221-usa-4cyl/gear-housing-driveshaft

I took some more photos of the water pump to show off both ends of #32.
https://photos.app.goo.gl/bSDQxxzf6fcYJYE99

The seal (#28) in your diagram is new. I replaced it when I replaced the impeller.

By the way, you saw in my video where I submerged the lower unit in water that it did pump water at the end, right? It failed at the beginning because I don't think I had it low enough in the water.
 
Well, I figured it out. I was looking at my video of the submerged lower unit and I noticed that right when the water came out the top it also came out the side. My first thought was that I didn't tighten up the screws enough. As I took the water pump off I happened to have one of the black plastic "insulators" (#31 on my parts diagram) fall out. When I went to put it back in, it occurred to me that those shouldn't be on the inside, but rather the outside.

It was a stupid error that I made when putting things back together because I was more worried about the gaskets and proper orientation of parts. I'm glad it was a easy fix! I hope this post saves somebody else the frustration that this has caused me.

Here are some photos of the insulator and how they were on the wrong side, along with a video of the tell-tale working properly!! :-D
https://photos.app.goo.gl/Lo6pRLCQcngz5wWt6

Thank you @fastjeff and @faztbullet for the advice!
 
Two things..... 1)Throw the rectangular muffs in the trash can, the cheap round ones work the best.... 2) I hope you bought an OEM pump, reason: the cup in the ss housing will start to rotate in the aftermarket pump and cause a high speed overheat.
 
I did buy the OEM impeller from boats.net, so I should be good there. Thanks for the advice about the square muffs. I'll keep a close eye on them and replace with the round ones.
 
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