Johnson 1976 6HP cooling system

[sw4n6xprt]

I have a 1976 6hp Johnson that does not have a pee hole on the power head. Is there a way of making one using parts from later models so that you know the water pump is working?

 

[jay_merrill]

Re: Johnson 1976 6HP cooling system

First, welcome to iboats! I think you'll enjoy your time here - there are lots of very friendly and well informed people.

While you could probably tap one of the passages in your head, I wouldn't bother if it were my motor. Water exits the exhaust in the midsection of a 1976 Johnson 6hp, and is very easy to see. Since it is just as easy to see that water from the typical steering position on your motor, there really isn't much point in having a "telltale."

If you are not seeing a relatively good sized spray from the midsection outlet now, you are not pumping an adequate amount of water, and it is time to find out why. The most likely candidate for replacement is the water pump impeller. Be aware, however, that one of the most common mistakes that people make in this regard, when running the motor in a barrel, is to not have enough water in that barrel. You have to make sure that you have enough water to completely submerge the water pump, which is located just above the point where the gearcase joins the midsection.

 

[Vic.S]

Re: Johnson 1976 6HP cooling system

In later models the telltale is connected to a tapping near the top of the exhaust manifold outer cover.

Somewhere on the Engine FAQs board http://forums.iboats.com/forumdisplay.php?f=31 there is a post describing how telltales can be added to early models.

I would not contemplate drilling and tapping that cover without removing it but it could be done. You would also need to drill a hole in the rear corner of the lower cover to mount the outlet nozzle. It would be important to either use a proper outlet or make something with a fairly small hole through it because if too much water was allowed to pass through the tell tale it would starve the later stages of the cooling system (basically the head) of water.

Later models I think, have a different outlet on the midsection. You certainly dont see much water issuing from them!


The recurring problem I have with a later model is the grommet at the top of the water tube blocking the flow. That's a pain to fix because both lower unit and power head have to come off to fix it. Hours of work just to renew a silly little grommet.

 

[F_R]

Re: Johnson 1976 6HP cooling system

I agree, you don't need to do anything. That big blowhole in the backside of the 1976 midsection is way better than any pee hole in the more "modern" ones. It should blow a healthy spray out that hole any time the motor is running. As Vic says, if it ain't broke, don't fix it.