Johnson 6hp cooling update

[gnarbrah]

First off, thanks for all the info and help getting my 1975 6 back to running. I replaced the impeller and the thermostat and it fired up and started spitting water immediately. I let it run in the barrel for about an hour with no problems. The only concern I have is when I throttle it up the water coming out the back gets almost too hot to hold my hand under. When at "idle" its warm but not scalding. Is this normal? Its running perfect and I'm ready to take it out for a day of cruising. Thanks!

 

[HighTrim]

Re: Johnson 6hp cooling update

Was this after running it in the barrel for a while?? The water heats up very quickly in that barrel, multiplying every time the water cycles through the motor.

 

[gnarbrah]

Re: Johnson 6hp cooling update

Its the big half of a 55 gallon drum and I had the hose running in it the whole time. After about an hour the water was warm but not any worse than the lake in August (I'm in Orlando). I mixed the fuel 50:1 so I'm hoping that should be everything to ensure its running as cool as its supposed to.

 

[wbeaton]

Re: Johnson 6hp cooling update

If you can hold your finger on top of the block for a few seconds while running then its cooling alright. I don't find that feeling the discharged water temp with my hand is a very accurate way to tell.

 

[iwombat]

Re: Johnson 6hp cooling update

The water coming out is mixed w/ exhaust. It's gonna be hot. It's not quite the same as a tell-tale in that regard.

 

[jbjennings]

Re: Johnson 6hp cooling update

The water coming out is mixed w/ exhaust. It's gonna be hot. It's not quite the same as a tell-tale in that regard.

That was a very helpful comment--I didn't think about that and was wondering the same thing about mine! I always do like WBeaton says though, depend more on feeling the block temp. I live down south, too, and it always feels hot coming out in the summer.
thanks,
JBJ

 

[gnarbrah]

Re: Johnson 6hp cooling update

Thanks for the replies. I can hold my finger on the block for a couple seconds so I'm guessing life is good. Thanks Wombat, I never even thought about it being mixed with exhaust coming out the back. That makes perfect sense. Speaking of a tell tale, I wouldn't mind having one. I did read Wombats post about installing them but I'm wondering if its possible to tap in at the plate that covers the thermostat on this motor? Its far and away the easiest spot to get to. Thanks!

 

[iwombat]

Re: Johnson 6hp cooling update

The problem with that is that your tell-tale will cycle on and off with the thermostat. The water jacket needs to be tapped upstream of the t-stat. Easiest place to put one is probably on the exhaust cover.

 

[pacman77]

Re: Johnson 6hp cooling update

I have a Johnson 6hp 1972 what is involved in changing the impeller,are there any seals that need to be replaced too get to it?
where is the impeller?

 

[jasper60103]

Re: Johnson 6hp cooling update

You should start a new thread.

 

[Vic.S]

Re: Johnson 6hp cooling update

I have a Johnson 6hp 1972 what is involved in changing the impeller,are there any seals that need to be replaced too get to it?
where is the impeller?

The pump is located on top of the gearcase so you have to remove that from the exhaust housing. you will have to rotate the flywheel/crankshft/drive shaft until the pin that supports the seal assy at the top of the drive shaft passes through a slot in the housing and you will have to disconnect the shift rod after you have lowered it a bit.
See parts diagram HERE.

You should get yourself a manual.