Another impeller issue

[Jis4Jeep]

I have read water pump issues all over this forum and I have tried everything. I replaced my water pump housing and impeller which was toast. Put new impeller on aligned the tube when I re-installed the lower unit. Blew air through the all the tubes and it flows. from the bottom to the top no obstructions. When motor is running I get air flow through the **** hole just no water. I took propeller off submerged into a bigger trash can making sure the water pump is submerged and still no water.

I read about leaving it running for 15 25 seconds to get things flowing and I did and nothing.

1984 7.5 mercury

Does it have a thermostat ?

 

[Jis4Jeep]

Re: Another impeller issue

Also I checked the the key on the output shaft that hold the impeller and its on right I orn the propeller and I see the impeller spin with the upper half of the water pump off. I have dropped in about 5 times making sure the tube was on right and to inspect the impeller and it still looks good. I read on another forum that some of the older mercuries might take up to 90 seconds I fond kinda of hard to believe they are a few youtube videos with my same motor and they start it and within a few seconds water flows from **** hole. Anyway the air coming out of **** hole smells like exhaust too which could mean that something is clogged. Going to work on in the morning and maybe try it on the lake get a little more water under the motor. Help PLease!!!!

 

[j_martin]

Re: Another impeller issue

Also I checked the the key on the output shaft that hold the impeller and its on right I orn the propeller and I see the impeller spin with the upper half of the water pump off. I have dropped in about 5 times making sure the tube was on right and to inspect the impeller and it still looks good. I read on another forum that some of the older mercuries might take up to 90 seconds I fond kinda of hard to believe they are a few youtube videos with my same motor and they start it and within a few seconds water flows from **** hole. Anyway the air coming out of **** hole smells like exhaust too which could mean that something is clogged. Going to work on in the morning and maybe try it on the lake get a little more water under the motor. Help PLease!!!!

Or the air coming out of the telltale could be exhaust, indicating a fault in the water jacket somewhere.

 

[Jis4Jeep]

Re: Another impeller issue

I ran my air gun through the telltale and shot air down through pick up vent nothing obstructing. ran wire through the lines from the lower unit and theres nothing blocking.

How tight should that water tube fit over the down tube. I notice the size of the tube is significantly bigger then then the down tube. I know for a fact the water tube is over the down tube but i think not a good enough seal maybe the water is coming through the water tube and shooting around the down tube. I hope I painted a good picture.

 

[j_martin]

Re: Another impeller issue

I ran my air gun through the telltale and shot air down through pick up vent nothing obstructing. ran wire through the lines from the lower unit and theres nothing blocking.

How tight should that water tube fit over the down tube. I notice the size of the tube is significantly bigger then then the down tube. I know for a fact the water tube is over the down tube but i think not a good enough seal maybe the water is coming through the water tube and shooting around the down tube. I hope I painted a good picture.

That's a guide tube. The seal is a rubber seal in the pump housing itself, below that guide tube. You should definitely feel a little resistance when it seats.

Once the water line is in place, that guide tube could disappear and it wouldn't make any difference.

 

[Wingedwheel]

Re: Another impeller issue

I just replaced an impellor on the same model engine and really had to get the leg deep for the water to start pumping. It drove me crazy(more so than normal) until I figured it out.

 

[Jis4Jeep]

Re: Another impeller issue

Thank you everyone but I think I just got a bad impeller. I was hearing noise and couldn't figure it out but I took it apart for the 10th time (really did) and i spun the shaft with my hand and you can tell the noise was from inside the water pump housing and sure enough the fit with the key on the shaft is just not a tight one. I am going to grab another impeller tomorrow unfortunately its not like I have a marine store near by I am probably going to have to drive to Ontario to find someone with it in stock. I am leaving tomorrow north west and I would love to get this motor figure out before i leave if not I bought a 55 thrust Prowler trolling motor today so at least I can save my arms from paddling to much.

Oh yeah so I took the impeller off and inspected it and where the key sits on that inside ring its crack and the impeller is loose so not a tight fit.

 

[bob1340]

Re: Another impeller issue

Oh yeah so I took the impeller off and inspected it and where the key sits on that inside ring its crack and the impeller is loose so not a tight fit.

That key deal on these 7.5 motors is poor IMHO. Original motors used a needle bearing type deal. Most kits you buy supply a T shaped deal. I put a very small dap of glue (Permatex High Tac) on the t shaped deal and place it on the shaft and let it dry for a while. This made installation much easier.

 

[Wingedwheel]

Re: Another impeller issue

Yes they make two size shafts for that motor. If my memory serves me right(usually doesn't) one is .044 and the other.052. I think but not sure. If you can mic your shaft it will help you get the correct one.(disclaimer) Don't quote me on those numbers, they are for reference only! LOL

 

[Jis4Jeep]

Re: Another impeller issue

That key deal on these 7.5 motors is poor IMHO. Original motors used a needle bearing type deal. Most kits you buy supply a T shaped deal. I put a very small dap of glue (Permatex High Tac) on the t shaped deal and place it on the shaft and let it dry for a while. This made installation much easier.

Your so right my brother came over to help me out and we went through the install from the beginning and the first thing he said and he knows nothing about boats "With the impeller being such a critical piece to the motor you would think they would have a much better way to hold the impeller in beside that silly key".

Thank you!!!

 

[Jis4Jeep]

Re: Another impeller issue

Yes they make two size shafts for that motor. If my memory serves me right(usually doesn't) one is .044 and the other.052. I think but not sure. If you can mic your shaft it will help you get the correct one.(disclaimer) Don't quote me on those numbers, they are for reference only! LOL

Understand! That is exactly the issue the key is just a tad bit too small and has to much play on the shaft. I will bring that up when I go to the parts store. Thanks!

 

[Jis4Jeep]

Re: Another impeller issue

I just got off the phone with a marine store on the way to where I am going and they have both impellers. Going to compare with old one and get the right one. Good call on 2 impeller sizes I wish the guy in the first marine store would of told me that instead I waisted a week messing with this motor. Thanks again!

 

[Wingedwheel]

Re: Another impeller issue

Good to hear, you'll be on the water soon.