91 Mercury 115 HP Water Pressure Problem

[MiBad]

I have a 91 Merc 115 HP that does not appear to have any water pressure. I am testing with a muff, but also tested with the lower unit in a plastic tub filled above the water intakes. There is no sign of peeing and I just hooked up a water pressure gauge and I get zero pressure.
Background: I bought the motor 3 years ago on a pontoon boat. It seemed to run great and peed as it should while in the lake when I tested before I bought it. I replaced the impeller shortly after I purchased it just in case and it was still peeing fine when used on the lake. At the time I didn't have a pressure gauge and I never tested this motor on a muff to see what was normal pee rate. After a couple of weeks the motor developed an ignition problem and did not get used for next 2 seasons. Due to health issues the motor was not winterized and sat outside during sub zero winters.
This summer: Ignition problem is fixed and when I initially fired it up it was peeing with the muffs but not a steady stream. I thought I would replace the impeller again since it was sitting for 2 seasons. After I replaced the impeller it does not pee at all. I think I checked all of the obvious (except put the motor in a full tank of water or in the lake - neither of which is practical for me at this time).
What I've done: Replaced the impeller - Pulled the lower unit again to make sure water pump tube was installed correctly. Reinstalled the lower unit. Installed a water pressure gauge from my old merc 150 (no indication of water pressure). Removed the thermostat (left it out for now while testing). Flushed out the pee hose that goes from the block to the exterior of motor with water pressure to assure no blockage. Back-flushed from the peeing port and the thermostat with water. Still no water pressure.
I have a question that came up while I was troubleshooting that I would appreciate if anyone has any knowledge. If I hook a hose to the water tube that the water pump connects to (with the lower unit and thermostat removed ) should the water travel through the block and come out the peeing port? It doesn't.
I currently have the lower unit removed and the water pump disassembled again. From what I can tell the impeller was installed correctly. I am going back to try some more troubleshooting. If anyone has any suggestions as to how to go about troubleshooting this it would be greatly appreciated. I am concerned that there might be some frost damage since I did not winterize, but I'm not sure best way to verify.
Thanks in advance.

 

[MiBad]

Update: I put the water pump housing back together since all looked good inside. I left the lower unit off while I tried to shoot water into various ports to see if I can tell if there are any seal leaks or internal cracks. I also checked the thermostat in a pot of hot water to make sure it was opening - it was opening ok.
I adapted a hose to the water pump tube and shot water up the tube. Water eventually came down the exhaust port. It never came out of the pee hole. I also took the thermostat cover off while shooting the water up the tube and the water did not make it to the thermostat. I tried stuffing a rag up the exhaust to create some back pressure and still no output at the pee tube.I adapted a water tube to the pee hose and alternately to the thermostat ports and shot a stream of water into both to flush them out. I'm not sure where the water should exit when I do these tests - or if these are even valid tests, It's difficult to tell if the water is exiting the exhaust plenum or the water tube.
I'm thinking of putting the thermostat and lower unit back together and trying again on the muff to see if I flushed anything out. I would put the boat in the lake to test in the water but it is a pontoon boat and I don;t have a trailer for it (it sits on dry land). I'm trying not to go to the expense of calling a marina to come by with a trailer to put it in the water unless I am relatively sure that the water pressure is OK.
Does anyone know if there is a good way to tell if the seal at the top of the water pump tube is bad with the lower unit removed? I don't want to disassemble any more than necessary and open a can of worms. Also, I noticed that some models of Merc outboards have a seal at the top of the drive shaft. Does anyone know if the 91 Merc 115 HP (4 cylinder) should have a seal at the top of the drive shaft? Mine does not have one.
Thanks.

 

[MiBad]

Update: After using a larger diameter tube to back flush from the pee hole (or tell-tale port) I was able to get enough pressure to see water flow from the water pump tube. However most of the water pours from the exhaust chambers so it't difficult to tell where the water is coming from. So, I plugged the exhaust ports with plastic bags stuffed with rags, This blocked most of the water but it still seeped through the seams. I also blocked the tube that the drive shaft goes up because I thought some of the water was coming from there as well. I was right, when I pulled the plug on the drive shaft tube (for lack of a better term) water poured down that tube. This was the reason I asked about the seal at the top of the drive shaft,
Let me know if anyone has any insight as to the problem - otherwise I'm going to put it back together again with the thermostat and see what happens, Maybe I'll get lucky and I back flushed some dirt blocking one of the ports somewhere.
Thanks

 

[MiBad]

I tried to run the motor on the larger water muffs that allow water to enter both water inlets on the lower unit. I let the motor run longer than usual (2 minute or so) and still no water out of the tell-tale. There was a spray of water coming out of the exhaust, but none out of the overflow. However I did notice that there was pressurized water coming out of what appears to be 2 drain holes in the front of the lower leg (above the lower unit - one hole horizontal and one vertical). Would this be normal or is water getting somewhere that it should not and exiting these holes? Or could this be why the motor should be in a tank or lake to build up enough water pressure to come out the tell-tale? Let me know if anyone has any ideas...thanks.

 

[MiBad]

To clear up where the pressurized water is coming from, the holes I mentioned above are in the front of the exhaust housing. As I asked, is this normal to have pressurized water coming out of these two holes with the motor running on muffs. If not, than does anyone have any clues as to where the internal leak could be?

 

[MiBad]

I wanted to update this since problem is now fixed. Early on when I replaced the impeller I also replaced the water pump to water pump tube seal. My problem was the fact that the Merc dealer gave me the wrong part. The '91 Merc 115 HP uses part number 43023. I can't say for sure what part the dealer gave me. The pressurized water I was trying to describe above was the water leaking from the seal out the drain holes. I now get 8, pounds of pressure using muffs.

 

[Chrsamss]

I have an ongoing problem with a 1992 115hp Merc, see: http://forums.iboats.com/forum/engi...ury-mariner-outboards/10019559-is-this-normal

I have water coming out of the top of the exhaust housing just under the head where the two motor mount rods come out. it only comes out when the RPMs are brought up.

Any thought on why the water is coming out and where the water is coming from, the tell-tale is still strong.

I have a small video that shows it well however I am not sure how to upload it


Thank you,

 

[MiBad]

Chrsamss - I don't recall seeing any water leaking under the head on my '91 115 Merc. , but I was running on a muff at idle and slightly above. I'll check to the next time I get a chance, but as someone mentioned in your other post it doesn't look normal.