1975 Johnson 40HP water pump problem

[kmilley]

Hey there everyone, hopefully, I can get some guidance on what to do with my motor as I can not figure out for the life of me why the thing is not pumping water... I'm fairly new here so if anything is wrong feel free to let me know. I picked this motor up for a good deal but can't seem to get it to pump lots of water.

Model number - 40E75C
Serial - C27387

1) took the lower unit apart and changed the impeller, noticed grommet that feeds the water up to the engine was messed up so replaced that and put it all back together, still not pumping water.

2) took the lower unit off again and inspected further by blowing air through the water system, air travels through perfectly but noticed the grommet below the powerhead was messed up a little so had the powerhead removed to change that grommet. still not pumping water.

3) tested the lower unit in water with a drill on the driveshaft to see if it was pumping water properly and everything was working perfectly. So removed the thermostat to see if water was making it all the way up and it was but not nearly enough water.

4) removed the head gasket to see if it was maybe leaking? (engine starts and idles perfectly) replaced the head gasket but did not pump water.

5) changed the impeller housing and even tried a different lower unit to see if the problem persisted... when the motor first started it was not pumping water for about 15 seconds but then started spewing water like it should for about a minute but then stopped.

Pretty well ready to give up on the motor at this point... other notable things include that the copper pipe where the water flows up has a hole in it (was told it cools the exhaust and it should still pump plenty of water upwards). The motor does pump was but VERY VERY little, not enough to cool it at all. The motor goes into fwd, rev and neutral all perfectly, but does not pump water...everything is lined up properly and the water is high enough on the motor for sure.

Any help would be greatly appreciated, as I am at a loss for words on this thing.

 

[fireman57]

If you are running it on muffs it won't pump that much. If you put it in a barrel make sure water is halfway up the midsection. The water pump is not self priming. Needs to be in water.You also could have a blockage in the system. Take the thermostats out and run a stiff wire and see if it dislodges anything. Could have a piece of the old impeller stuck somewhere. Also take some weedeater string and go up through the telltale to make sure it isn't clogged my mud, sand, or other crud.

 

[hardwater fisherman]

No tell tale or thermostat on that motor. And very hard to run that one on muffs.

 

[hardwater fisherman]

Hey there everyone, hopefully, I can get some guidance on what to do with my motor as I can not figure out for the life of me why the thing is not pumping water... I'm fairly new here so if anything is wrong feel free to let me know. I picked this motor up for a good deal but can't seem to get it to pump lots of water.

Model number - 40E75C
Serial - C27387

1) took the lower unit apart and changed the impeller, noticed grommet that feeds the water up to the engine was messed up so replaced that and put it all back together, still not pumping water.

2) took the lower unit off again and inspected further by blowing air through the water system, air travels through perfectly but noticed the grommet below the powerhead was messed up a little so had the powerhead removed to change that grommet. still not pumping water.

3) tested the lower unit in water with a drill on the driveshaft to see if it was pumping water properly and everything was working perfectly. So removed the thermostat to see if water was making it all the way up and it was but not nearly enough water.

4) removed the head gasket to see if it was maybe leaking? (engine starts and idles perfectly) replaced the head gasket but did not pump water.

5) changed the impeller housing and even tried a different lower unit to see if the problem persisted... when the motor first started it was not pumping water for about 15 seconds but then started spewing water like it should for about a minute but then stopped.

Pretty well ready to give up on the motor at this point... other notable things include that the copper pipe where the water flows up has a hole in it (was told it cools the exhaust and it should still pump plenty of water upwards). The motor does pump was but VERY VERY little, not enough to cool it at all. The motor goes into fwd, rev and neutral all perfectly, but does not pump water...everything is lined up properly and the water is high enough on the motor for sure.

Any help would be greatly appreciated, as I am at a loss for words on this thing.

Where is the thermostat that you removed? I have 2 of these motors and neither one has a thermostat. With the lower unit off shoot some water up through the copper pipe it should gush out the exhaust relief and the midsection.. Make sure the impeller key is in place..

 

[hardwater fisherman]

The exhaust cover on my motor was leaking water years ago.. And the motor was getting a little hot. I changed the inner and outer gaskets and swapped out the inner exhaust plate. After that the water leak was gone and the motor ran cooler... I do not know if it was just by chance that it ran cooler after..Or maybe the hot exhaust gases were mixing with the cooling water?

 

[F_R]

Yeah, no thermostat on a '75. What is wrong with that model #? You say it is deep enough in the water but the symptoms say different. What do you call "deep enough"?

 

[kmilley]

Hey guys,

firstly, thanks so much for all the responses, they are very much appreciated ... obviously I forgot to mention a few things but I’ll add more info now.

the motor did have a thermostat and was located on the headplate slightly above the top spark plug.

I was running the motor in a large steel tank, and the water was probably 4” above the water pump, almost near the exhaust relief where the water should be coming out.

With the lower unit off I tried pushing water through the copper pipe up to the removed thermostat and it didn’t make it at all but blowing air through it went without any problem. The key was in the impeller and everything worked on the lower unit when it was used with the drill..

I did hear that the exhaust gasket could also be the problem, but have not tried that yet.. could that be the final piece of he puzzle? Lol

thanks again so much everyone!

 

[racerone]

=There are folks here who say there is no thermostat on a 40E75C-----So what this means is you may not have the motor you think you have.-----Post some pictures as the wee plate with the model may not belong to your motor !!

 

[F_R]

Yep, saying it one last time for emphasis. There is no thermostat on a 40E75C, or even a place to put a thermostat. So if you have a thermostat, you do not have a 40E75C.

 

[racerone]

Any update ?---Any pictures ?

 

[kmilley]

Sorry for the terribly long delay... I have been away camping all weekend and didn't have access to my phone...

My mechanic was also very surprised to see that it had a thermostat but there was in fact one in there, so we removed it to see if water was pumping out but it was barely getting there at all, not gushing out.

I picked up another 40HP motor just because I found one super cheap so I am going to continue looking into this problem.. but I do have to pick up my other motor from the mechanic a couple of hours away.

hopefully, the pictures upload, as you can see there is a spot for the little thermostat! Hopefully this helps a little bit..

 

[racerone]

So I see.-----That does not appear to be factory stuff.----Never seen a thermostat on one of these.------I have to wonder if it actually works.

 

[kmilley]

could I perhaps try to pull the head gasket and put the one from my new 40HP ? Because I have not had very much luck with anything and the motor starts up awesome, I would love to have it functioning properly. Or are there any other ideas that you guys may have? I have two of the same motors now pretty much so I can try to see if the new one will pump water.

Really appreciate the replies and the knowledge being shared... Thanks again

 

[F_R]

Could it be a Canada thing???

 

[racerone]

Looks RUSSIAN / POLISH to me.

 

[jimmbo]

Could it be a Canada thing???

No, the Canadian 75 40hp was the same as the US model. A stat in that location makes no sense.