Johnson 25HP issue

[jonmac3569]

Looks like some sort of water by pass restrictor :?:

That's interesting. I know some cars use those, what would that do in this motor? Would it restrict the flow of the water and make it run hotter?

 

[lckstckn2smknbrls]

You should ask on www.Iboats.com in the evinrude johnson forum.

 

[crazymanme2]

That's interesting. I know some cars use those, what would that do in this motor? Would it restrict the flow of the water and make it run hotter?

I believe its when your thermostat is closed it permits water to flow for the tell tale :?:

 

[jonmac3569]

Thanks for the reply. I took it out today and I still have the tell tale and it is running fine. It's not in the parts lists or service manual so I am going to leave it out.

 

[jonmac3569]

Makes me wonder if someone could have "failed" that thermostat on purpose, then blocked the bypass valve in order to make the motor run cooler. That way all of the water would flow through the thermostat.

Don't know why they would do that becuase it was causing a lot of carbon build up in the motor and I was fouling plugs left and right.

 

[cajuncook1]

If your your water pump system is functioning properly then water should come out of all the time. The thermostat opens up at a certain temperature about 140 to 145 degree F on your motor. This completes the water circulation path through the water jacket pathways around the cylinders. If the engine temperature is lower then the thermostat stay close and water still circulates but not around the water jacket cylinders, so the motor temp can warm up. So water should always becoming out of the tell tail or the exhaust relief hole.

Here is a diagram of a 1973 25hp Johnson water flow pathway and cooling. Should help you to understand.

The piece of junk you found in the thermostat hole is odd. Maybe the person that service the motor prior to you investigating the thermostat was a bit sloppy and accident drop that in there. I dunno!!

Oh, just wanted to let you know, you motor does not have water re-stricters. Larger hp motors that had 3 or more inline cylinders would.

 

[jonmac3569]

Thanks, yeah looks like they were blocking off the bypass line for some reason. Strange

 

[cajuncook1]

Thanks, yeah looks like they were blocking off the bypass line for some reason. Strange

Did you ever find out what was causing your lower unit kick out of gear or was it a spun hub on your prop???

 

[jonmac3569]

Did you ever find out what was causing your lower unit kick out of gear or was it a spun hub on your prop???[/quote]


Yep, actually yesterday I tried putting the mark with a waterproof pen on both the hub and prop and sure enough it was spun after my last run. Glad it was that and not a gear issue! Thanks for that link!

 

[cajuncook1]

Cool 8) , glad to hear there is a happy ending to this story!!!

 

[jonmac3569]

Put a new prop on and took it out today. Ran great! hopefully no more issues for a while!