40hp Mercury Force not spitting water out the spout

[78hustlerpro]

1994 Mercury Force 40hp isn’t pumping water out the upper spout. Motor fires up fine. I had lower unit off repairing the bearing cage. I think I got all the parts back in the right position, I didn’t have a problem getting the lower unit back on the motor. I looked at the impeller while the lower unit was off and it appeared to look fine. I’m not sure if I accidentally have something incorrect when I reinstalled the lower unit. Any guidance would help. All I know to do is drop the lower unit again and replace the impeller.

 

[Mercurylips]

Sometimes the water tube doesn't go back in place in the pump housing. Happens to me all of the time. Try to go slow and use a small bladed screwdriver or something to make it set in before tightening up all the nuts. A little help from a friend is good.

 

[78hustlerpro]

correct me if I’m wrong, but with the motor in neutral and idling, water will still circulate up, cool the head and come out the upper spout?

 

[roscoe]

Yes it should.
The drive shaft is spinning whenever the engine is running, so the water pump will be spinning and should pump water.

 

[78hustlerpro]

Thanks. I will pull lower unit off and check everything. I have a new impeller on the way. I figured I will just replace it since I will have it open again. If that doesn’t solve the issue then I don’t know what else to do.

 

[78hustlerpro]

Should I get a bucket for testing? I have ear muffs but I’m not sure if that is sufficient enough. It’s sufficient for my ski boat but then again that motor and outdrive is about 25 years newer than this motor.

 

[Mercurylips]

Should I get a bucket for testing? I have ear muffs but I’m not sure if that is sufficient enough. It’s sufficient for my ski boat but then again that motor and outdrive is about 25 years newer than this motor.

You can use muffs. Just don't turn the hose pressure up too much. A good flow should come when the motor is running but not peeing when it is not running. The motor won't be damaged for just a good test (short). I use a trash can at times but it isn't really necessary since the water gets kicked out in gear.

 

[78hustlerpro]

So I have the lower unit off, the impeller looks fine. Could I have had something incorrectly installed causing there to be no water coming up the water tube? I hate to reinstall and have the same problem occur.

 

[roscoe]

Make sure water tube is inserted into block, and inserted into the top of the water pump as you install the gearcase.

 

[Mercurylips]

So I have the lower unit off, the impeller looks fine. Could I have had something incorrectly installed causing there to be no water coming up the water tube? I hate to reinstall and have the same problem occur.

You might make sure the little key is in the correct position to lock the impeller on the shaft. I have missed that one on my own. If not on the shaft will spin without pumping, of course.

 

[78hustlerpro]

You might make sure the little key is in the correct position to lock the impeller on the shaft. I have missed that one on my own. If not on the shaft will spin without pumping, of course.

after watching a video, I know what key you are referencing to. The first time I reinstalled everything I didn’t know about that key. That key seems like it’s dummy proof though like everything should only go one way. Everything seemed to go together fine the first time though. Maybe in some miraculous way I was able to get everything installed without having that key lined up properly. I know for a fact that the key is lined up in the small slot this time. I just haven’t reinstalled the lower to test yet. I was waiting for some responses on here before I give it another go. The reason I believe it could be that and not the water tube being improperly lined up is there was absolutely no water evidence in the lower unit or up the water tube. It’s like it wasn’t spinning at all.

 

[78hustlerpro]

Also on a side note, I had the prop, prop shaft and drive gears out at one point because I had to fix the bearing cage. I got all that back together and it only goes one way. I don’t think that would have anything to do with the motor not getting water to be cooled.

 

[444]

Are you getting water out the pee hole? Are you getting water coming out through the prop exhaust?

 

[78hustlerpro]

Are you getting water out the pee hole? Are you getting water coming out through the prop exhaust?

Im not getting any water out the pee hole, it’s hard to tell if I’m getting water out the prop exhaust due to the muffs creating a lot of excess water in the area.

 

[Mercurylips]

Just a thought. Is the impeller installed backwards, perhaps. That just about covers all the humanity I have been guilty of.

 

[78hustlerpro]

Just a thought. Is the impeller installed backwards, perhaps. That just about covers all the humanity I have been guilty of.

It’s not backwards, it’s the same impeller that was in last year and it worked fine last year. All I did was pull it apart to make sure it was still good. My only guess that happened is I didn’t get that key that’s on the drive shaft properly lined up in the slot that it’s deaigned to go in.

 

[444]

Im not getting any water out the pee hole, it’s hard to tell if I’m getting water out the prop exhaust due to the muffs creating a lot of excess water in the area.

Ok. You shouldn't have the garden hose turned on full bore. After all the impeller is designed to suck not be pressure fed. I know yours is a lot smaller however with my 175hp and my old 90hp the water coming out the prop was very obvious. I don't know how the cooling system is setup on these but does the thermostat block water flow until warm-up?

 

[78hustlerpro]

Ok. You shouldn't have the garden hose turned on full bore. After all the impeller is designed to suck not be pressure fed. I know yours is a lot smaller however with my 175hp and my old 90hp the water coming out the prop was very obvious. I don't know how the cooling system is setup on these but does the thermostat block water flow until warm-up?

I would have to read in the manual on how the thermostat is set up. If I remember from last year it started flowing water within a minute or two after started. I will turn the water pressure down and reinstall the lower now that I know for a fact that the impeller is lined up on the drive shaft key.

 

[78hustlerpro]

So I installed the lower, started it up again and no water still. Could the thermostat be stuck closed and not opening for water to pump through?

 

[78hustlerpro]

Well it isn’t the thermostat. There isn’t one in the housing! I don’t know how that happened. I guess the owner before me took it out