Johnson 40, cooling probem!

[pizzafellow]

I have a 76 Johnson 40 that I have been working on. Now it starts and runs in the tank, shifts both ways nice and smooth. But the is no water coming out that shows proper cooling. I had dropped the LU and checked the water pump. Everything looks good and impeller looks brand new. And when I had the cylinder head off I poured water into the block water passageways it came flowing down from that copper pipe in the LU.
Does the motor need to reach a certain temp before the water pump starts? I am new to boating and outboards, thnks for any help in advance.

 

[5150abf]

Re: Johnson 40, cooling probem!

If the motor is running the pump is running, it is hooked to the drive shaft which is spinning if the motor is running.

Make sure the lower is submerged enough to pump, above the top cavitation plate.

Worked on a friends 72 50 and it is hard to tell if it is pumping cause there is no tell tale(pee hole).
As long as the engine doesn't get really hot while it is running it is okay.

You should be able to touch the engine for a 3 count

 

[pizzafellow]

Re: Johnson 40, cooling probem!

Thankyou. I did not know there is no (pee hole) on that motor . Is there any way to test the exact engine temperature?

 

[jbjennings]

Re: Johnson 40, cooling probem!

Just my 2 cents:
If it doesn't have a tattle-tail, it should have water spraying out the exhaust port in the mid-section. If not, it's not pumping. As was said, you may not have the water in your barrel high enough--very common mistake. I'd put the water level just below the exhaust port just to be sure. If no pumping, you either didn't put the impeller key in or the water tube isn't in the grommet of the pump. Your water inlets could also be clogged. I don't see the need to know the exact temp. If you can't hold your hand on the cylinder head when idling, it's not pumping right. I think some folks use that plastic stuff you can sit on the cylinder head and it melts at a certain temp. but I've never used any and couldn't help there.
JBJ

 

[pizzafellow]

Re: Johnson 40, cooling probem!

Thankyou jbjennings for your input. I will the check the water level today, and if it's still not spraying I will recheck the key of the impeller. I will post the results. Thanks again

 

[pizzafellow]

Re: Johnson 40, cooling probem!

I dropped the lower unit, checked the impeller key, good. Checked the brass tube , it fits in the water pump. Looked again at the impeller, looks new. Added more water to the test bucket, water pump completely submerged. Started the motor , no sign of water pumping , and cylinder head got too hot to touch for more than one second !! There is exhaust smoke coming out of the water outlet.
I just read now a post about air bleeding hole in the water pump housing. I didn't know such a thing existed so I guess I will have to to check it too!
Any other suggestions? I am stuck here LOL
Thnx
It shifts with no problem which means the rod is turning fine!!
Is there a thermostat on this motor? Could not see it on the diagram!!

 

[pizzafellow]

Re: Johnson 40, cooling probem!

Another question: is there a way to install a water pressure valve on the head?