1961 Johnson Sea Horse 75hp Points Set

[Clippership821]

Thanks for all your advice on adjusting the points. I got her in the lake again this weekend. She started up like a dream. All pistons firing and right in time too. I'll try not to hurt my arm patting myself on the back. lol. Anyways, I took the vernatherm out but not the stat because I'm as green as newly sprouted grass when it comes to these babies. So, naturally when I got her to full speed i(n the no wake zone with everyone on the bank screaming at my poor wife and I.!) The overheat light went on. Thank God, what's all the commotion about? Immediately turned her around, (the boat) and killed the motor. We were only about 30 yards from the launch so we paddled in and got her out. But, while we had it going it was lovely. Smooth ride. Man, she was hot as a pistol though when I got the cover off. So, I hope I didn't overheat it too much. The paint blistered on the exhaust cover. After she cooled down, I took off the stat and someone had lock sealed the cover to the gasket and plate. No way I was getting that apart to remove the stat. I pushed in on the stat to break it loose (it was stuck closed) and to see that spring would give. tested the vernatherm in some boiling water to see that it was expanding. It was. So now I have it back together and I'm just waiting to put it in the water to see if she cools...Over for now... whew.

 

[tashasdaddy]

Re: 1961 Johnson Sea Horse 75hp Points Set

have you changed the impeller, rebuilt the water pump?

 

[Clippership821]

Re: 1961 Johnson Sea Horse 75hp Points Set

I changed the impeller. Did not put a new kit in....

 

[Clippership821]

Re: 1961 Johnson Sea Horse 75hp Points Set

Well she's still getting hot. After about 10-15 minutes Bing! The red dash light comes on. I saw a lot of water coming out the back...so it seems that the pump and stat are working just fine. BTW I did put a new seal ring in when I did my impeller. I'm starting to suspect the heads.....Is that a possibility? I did see in the manual if the water chambers are corroded that could cause over heating. Like I said. Seems like the pump and the stat are working. Anyway to tell for sure??. I'd hate to bust the lower unit apart if I don't have to. Thanks...

 

[F_R]

Re: 1961 Johnson Sea Horse 75hp Points Set

You aren't going to like my advice: Put in a whole new water pump. Put all the parts back in the thermostat. Replace both head gaskets and the exhaust cover gaskets...they have been overheated and will leak either now or later.

Is the exhaust outlet thing in place on the gearcase, behind the prop? Is the screen in it?

 

[Clippership821]

Re: 1961 Johnson Sea Horse 75hp Points Set

Thanks F R ...Hey, whatever it takes. I want to get this thing going. Yes, The exhaust outlet is there with the screen. ... I wonder why it's over heating? over

 

[Clippership821]

Re: 1961 Johnson Sea Horse 75hp Points Set

new pump including impeller?

 

[Clippership821]

Re: 1961 Johnson Sea Horse 75hp Points Set

Does installing a new pump include the impeller I just put in? It has less than 15 minutes wear on it. Thanks

 

[BillP]

Re: 1961 Johnson Sea Horse 75hp Points Set

If you've already replaced the impeller I'd look somewhere else for the problem...it could be a bunch of things, spark plugs too hot, too little oil in the gas, water galleries plugged, water tube not seated properly, etc. About 20 yrs ago I had a 1965 75hp Johnson that had the same symptoms as yours. It would run fine for 10-15 minutes at full speed and then the light would come on...the temp sensor was faulty. I used a procedure listed in a repair manual to check it. If your motor isn't pushing a lot of steam out of the exhaust it probably isn't running hot.

 

[guy74]

Re: 1961 Johnson Sea Horse 75hp Points Set

I think I'd test the over temp sender. I've had tempature guages and idiot lights send me on wild goose chases several times.

 

[Clippership821]

Re: 1961 Johnson Sea Horse 75hp Points Set

Thanks for all the responses. Finally got "The Queen" up and running. I had to drop the lower unit again and align the water tubes. Duh huh!! Lower unit got a good power washing from the inside out though. She's running cool as a cucumber now with the new pump. Got to take the family on the maiden voyage around the lake. It's got a lot of power. 1st time I took her out she ran right on 4800 WOT. No probs. Second time after I put in some more gas. I couldn't get the bulb pumped up tight. I eventually got it started but it was cutting out WOT and when I pull the throttle back it would catch up. Surging back and forth like that. Like it was running out of gas.....any ideas?
At least she's running cool now...that's a plus....now it's just work out the bugs. Over