johnson 18 hp new water pump but no water coming out

[bigmoe]

1965 johnson 18 hp fd-19

I just bought this motor and swapped out the water pump with a new sierra kit 18-3377. It wasnt pumping water before the swap because the old impeller was in bad shape. I got this one installed and Im not getting water coming out of the tell tale hole. I have the whole lower end submerged in water. I removed the lower unit again to make sure I didnt damage the new pump. I also blew compressed air through the pick up tube and it seems clear.

Heres some pics. Thanks guys.

 

[jbjennings]

Re: johnson 18 hp new water pump but no water coming out

The usual culprits:
The water level in the barrel is too low, needs to be about 3 or 4 inches below the exhaust relief, or at least a couple of inches above the water pump housing.
The drive key isn't in the impeller---I saw your key was present in the pic so that shouldn't be it......
The water tube isn't in the grommets properly. Your grommet looked like it might be a little pinched on top of the pump housing but I doubt that's a problem.
Try using some fuel line and duct tape to put a water hose on the water tube and see if it'll flow water through the powerhead by the water hose. If not, it could be blocked water jacket passages, or leaky exhaust plate gaskets or cylinder head gasket.
Is anything at all coming out of the exhaust relief? That motor doesn't have a tell-tale hole.
Good luck,
JBJ

 

[emckelvy]

Re: johnson 18 hp new water pump but no water coming out

Pull the thermostat out and start the motor without the thermostat cover installed. See if water comes rushing up into the head and out the 'stat opening. Obviously you don't want to run it like this for long, only to check for water coming out.

Bolt the cover back down without reinstalling the 'stat. Fire 'er up and if she's now pumping water, likely the 'stat is shot.

If no water, you may have a blown head gasket or leaking exhaust manifold (less likely) which is blowing exhaust into the cooling system.

You can check this by lighting off the motor w/o the 'stat cover, letting water rise up and then with the motor still running, slap the cover back on.

If exhaust is blowing into the block, the increased pressure blows water right back out. Taking the 'stat cover off relieves this pressure and water pump pressure will overcome and spill out the top.

If the motor has this problem, reinstalling the cover while running will likely foul a plug from water ingestion. At least a good way to diagnose.

Now, if you're not pumping water even with the 'stat cover removed, something is still amiss.

Pull the L/U back down and run water up the supply tube, with the 'stat cover removed see what happens.

Either something is plugged or the pump ain't pumping. You could also try submerging the lower unit and spinning the driveshaft with a suitable drill motor etc. Even by hand you should see some pumping action.

BTW, did you seal the pump plate to the gearcase, and also the pump housing to the pump plate? Some won't pump at all unless this is done. I see some gasket goop in the pic but can't tell if it's old or not.

Permatex #3 works well for this, even better get some OMC Gel-Seal or Loctite/Permatex 518 anaerobic sealer. This stuff cures when the parts are assembled and will fill slight imperfections.

Anyway, there's a few more things to think about. What Fun!........ed

 

[bigmoe]

Re: johnson 18 hp new water pump but no water coming out

The usual culprits:
The water level in the barrel is too low, needs to be about 3 or 4 inches below the exhaust relief, or at least a couple of inches above the water pump housing.
The drive key isn't in the impeller---I saw your key was present in the pic so that shouldn't be it......
The water tube isn't in the grommets properly. Your grommet looked like it might be a little pinched on top of the pump housing but I doubt that's a problem.
Try using some fuel line and duct tape to put a water hose on the water tube and see if it'll flow water through the powerhead by the water hose. If not, it could be blocked water jacket passages, or leaky exhaust plate gaskets or cylinder head gasket.
Is anything at all coming out of the exhaust relief? That motor doesn't have a tell-tale hole.
Good luck,
JBJ

I had the water above the upper pick up but below the pump housing.

The drive pin is in.

Checked the grommet and it seemed fine.

I will try the water test tomorrow.

Only exhaust is coming out of this area, see pic. Shouldnt water come out of here also?

 

[bigmoe]

Re: johnson 18 hp new water pump but no water coming out

Pull the thermostat out and start the motor without the thermostat cover installed. See if water comes rushing up into the head and out the 'stat opening. Obviously you don't want to run it like this for long, only to check for water coming out.

Bolt the cover back down without reinstalling the 'stat. Fire 'er up and if she's now pumping water, likely the 'stat is shot.

If no water, you may have a blown head gasket or leaking exhaust manifold (less likely) which is blowing exhaust into the cooling system.

You can check this by lighting off the motor w/o the 'stat cover, letting water rise up and then with the motor still running, slap the cover back on.

If exhaust is blowing into the block, the increased pressure blows water right back out. Taking the 'stat cover off relieves this pressure and water pump pressure will overcome and spill out the top.

If the motor has this problem, reinstalling the cover while running will likely foul a plug from water ingestion. At least a good way to diagnose.

Now, if you're not pumping water even with the 'stat cover removed, something is still amiss.

Pull the L/U back down and run water up the supply tube, with the 'stat cover removed see what happens.

Either something is plugged or the pump ain't pumping. You could also try submerging the lower unit and spinning the driveshaft with a suitable drill motor etc. Even by hand you should see some pumping action.

BTW, did you seal the pump plate to the gearcase, and also the pump housing to the pump plate? Some won't pump at all unless this is done. I see some gasket goop in the pic but can't tell if it's old or not.

Permatex #3 works well for this, even better get some OMC Gel-Seal or Loctite/Permatex 518 anaerobic sealer. This stuff cures when the parts are assembled and will fill slight imperfections.

Anyway, there's a few more things to think about. What Fun!........ed

I didnt seal the pump housing because it wasnt sealed when I took it apart. I dont think its a head gasket because the plugs look ok. A leaking exhaust is a possibility because I have noticed some oil dripping down from somewhere under the engine. It might be from the fuel pump also because I saw some coming from there too.

Looks like I have some checking to do.

 

[bigmoe]

Re: johnson 18 hp new water pump but no water coming out

Does anyone know if this is a pee hole? Shouldnt water come out here?


Edit: I just shot water up the pick up tube and got water to come out of this exhaust port in the pic below. Is that a good sign? Maybe I need the lower unit submerged in water above the pump? Thanks guys.

 

[Sea18Horse]

Re: johnson 18 hp new water pump but no water coming out

Yes, correct water should spray out from there. And the water level in your barrel needs to be at least up to the lower mounts there. Preferably an inch or two higher if you can manage it. The water pump housing needs to be completely submerged. It will not self prime.

Cheers....................Todd

 

[bigmoe]

Re: johnson 18 hp new water pump but no water coming out

Yes, correct water should spray out from there. And the water level in your barrel needs to be at least up to the lower mounts there. Preferably an inch or two higher if you can manage it. The water pump housing needs to be completely submerged. It will not self prime.

Cheers....................Todd

Thanks Todd.

 

[jbjennings]

Re: johnson 18 hp new water pump but no water coming out

The yellow arrow in your pic is pointing to the exhaust relief, and as stated, it should spray water out of there along with some exhaust.
I'm still suspecting the water level will solve your problem.
Good luck,
JBJ

 

[bob johnson]

Re: johnson 18 hp new water pump but no water coming out

take the assembled lower unti and stick it mostly underwater and drive the drive shaft with a 1/2" drill,, and see if it pumps water.....since it is a large hole coming out of the pump housing it wont be a strong thin stream, it will be a large low pressure volume of water...but it will verify the pump is pumping...

i also think it is just you need the lower unit deeper, I went through the same thing with a 15...wasnt deep enough in water.

good luck

bob

 

[bigmoe]

Re: johnson 18 hp new water pump but no water coming out

The yellow arrow in your pic is pointing to the exhaust relief, and as stated, it should spray water out of there along with some exhaust.
I'm still suspecting the water level will solve your problem.
Good luck,
JBJ

Got water pumping now. Water level was the problem. Thanks alot guys.