1989 Mercury 115 'Tower of Power' with no tell-tale after installing new waterpump

rvbrlb

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I have a 1989 Merc 115 outboard, 4 cyl. I just bought the boat and figured that no tell-tale was the typical worn out impeller, so did not think much about the purchase, as this is a relatively easy fix. I have checked the tell-tale line several times and it is not plugged. I replaced the water pump, and still cannot get water out the tell-tale hole. I checked the thermostat and it was clean and opened when put it in hot water on the stove, so I reinstalled. I now have the lower unit back off and have tried to run water thru the motor via a garden hose with a spray nozzle that sealed on the water tube nicely, with the engine off, and I still cannot get any water out the hole; is this a way to see if some passages are plugged, or do I need the lower unit assembled and the motor running to tell? If this method should work, what would be the next step to find the restriction? How much disassembly might this need? Thanks in advance for any help!!
 

oldman570

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Re: 1989 Mercury 115 'Tower of Power' with no tell-tale after installing new waterpum

Hooking the hose to the water tube with the LU off should work. You can remove the stat and see if you get water from the hose at that location. If your getting water there, use a air hose with a blow gun and see if you can blow air back to the stat from the tell tail. this will narrow it down. JMO
Oldman570
 

Texasmark

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Re: 1989 Mercury 115 'Tower of Power' with no tell-tale after installing new waterpum

First of all your engine information is confusing. The "Tower of Power" was the 6 in line engine and although I bought a 115 new in 1989, registered as such, folks on here said that they stopped making them in 1988. Well maybe so and they used those last engines to fuel the '89 market which makes sense. I had it on a new '89 Ranger bass boat registered as such.

It's replacement was the loop charged 4 cylinder of an improved design since the basic tower was from a 1940's 4 cylinder workup.

The tower did not have a thermostat so you can't plumb pee off that. I don't remember where it came from but probably from the water jacket cover over the top of the pistons; likely place.

If you have a 4 cylinder the service manual shows the water outlet to be off the exhaust manifold water jacket cover, right where my 90hp (little brother engine) 3 cylinder is located. That is a separate water circuit from the thermostatically controlled block water circuit. You have to have cooling water over the exhaust ports continuously while the engine is running; no stat on that. There is an outer cover plate, an inner cover plate and then you are looking at the exhaust ports of the cylinders. You could have corrosion blocking off the flow. If water to the cover is plugged and you have run the engine any length of time your paint on that cover is probably peeling from the heat.

I mean, like follow the hose!!!!!

So, which do you have?

When you pulled out the impeller, were any parts of the blades missing?

Mark
 
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rvbrlb

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Re: 1989 Mercury 115 'Tower of Power' with no tell-tale after installing new waterpum

Thanks for the info, guys!. I have a 4 cyl, 1989 115 hp that originally came on a Lund Pro V. The impeller that I removed appeared in great condition, as the previous owner said that he had it changed this spring, so this appears to be true. I'm not an expert on these, so sorry for the 'Tower of Power ' confusion!

I did have the thermostat off and ran water backwards thru that opening, and water did flow down and out towards the LU. I also took off the tell tale fitting and pumped water back thru that way with similar results. But when I put the hose on the LU and try to push it upwards, as if the impeller was doing its job, I get a burp and maybe a drop of water out the tell tale, then the rest seems to come back down the exhaust area...but it's hard to tell exactly where it's coming back from. I suppose that there could be some impeller pieces somewhere from before, but thought they would have been flushed out by now. How much air pressure can I safely put in the system is I try that method? I will try to get some pics tonight and post. Thanks again!
 

Texasmark

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Re: 1989 Mercury 115 'Tower of Power' with no tell-tale after installing new waterpum

Water pressure is on the order of 10 psig. Air hoses run 100. Be careful. If you/PO had a really bad impeller that had broken pieces that could have lodged in places you have to find them. If all else fails, remove the exhaust manifold covers and on the muffs see if you are getting water up to your exhaust manifold. If so, just walk through the parts. If not, then you have a clog in the powerhead to mid section interface and need to address this.

Mark
 

rvbrlb

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Re: 1989 Mercury 115 'Tower of Power' with no tell-tale after installing new waterpum

I stopped at the semi-local boat shop and he told me that this model would not pee out the tell tale hole until the engine was warm enough for the thermostat to open. I tried removing the thermostat and still could not get any water to exit there, just back down the exhaust channel. Does this sound right?? I thought all outboards pee'd all of the time, but now am wondering...
 

rvbrlb

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Re: 1989 Mercury 115 'Tower of Power' with no tell-tale after installing new waterpum

Here is a pic. I ran it with ear muffs on for a few minutes and it did not get too hot to touch on the side, but it never did pee any. I can blow air and water both back thru the tell tale hole and it seems to be open, but it won't pee out as I feel it should during normal operation. I suppose that it's time to take it to the lake an try to monitor it there....(??)

Here is a picture of the engine for reference (I hope this works...):
'T' = thermostat location
'P' = poppet location
'TT' = tell tale exit

1989 merc 115.JPG


Thanks again guys for the advice!
 

rvbrlb

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Re: 1989 Mercury 115 'Tower of Power' with no tell-tale after installing new waterpum

I finally got up the courage to take it to the lake and try to see if it would pee once it got up to temperature, as I could not achieve this with the muffs on. I am happy to say that it did! So, I have learned that not all engines pee all of the time, some wait until they can pee warm!! So I am happy now, and hopefully this will help some fellow readers in case they find similar situations. Thanks to those who chipped in with advise!
 

Texasmark

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Re: 1989 Mercury 115 'Tower of Power' with no tell-tale after installing new waterpum

I stopped at the semi-local boat shop and he told me that this model would not pee out the tell tale hole until the engine was warm enough for the thermostat to open. I tried removing the thermostat and still could not get any water to exit there, just back down the exhaust channel. Does this sound right?? I thought all outboards pee'd all of the time, but now am wondering...

BS!
 

Texasmark

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Re: 1989 Mercury 115 'Tower of Power' with no tell-tale after installing new waterpum

If all else fails, get a gasket set for the exhaust manifold cover and pull it off. Then you can answer your question as to why there is no water coming out of the pee hole.

Mark
 
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