1975 Johnson 70hp binding on start

[Nomad767]

My brother in law enlisted me to help him after he bought a new lower unit for his motor. The lower unit was a 1980 model but he was assured it would match up. This outboard is model #70ESL75E. The reason he replaced the lower unit was because when he bought it, he did not realize the lower unit had no oil in it and trashed the bearings, and the water pump ended up toasting also. Because of the way the old lower end water pump looked, he decided to put a new one on the lower housing he just bought. All fine and dandy, we put it together and put the lower unit on. Now it seems like the driveshaft is binding when we try to start it and when we pull ithe lower unit, the driveshaft is hard to turn with the water pump on it. We take the water pump off, and the things spins like a champ. Put it back on and it spins with a little difficulty, but when we put it back on, same thing. Take it back down and the driveshaft is harder to turn than when we put it back on. We are stumped. He turned the engine over without the lower unit on and it turns over fine. With it, it seems like it bogs on a stroke. We verified the exhaust on the lower unit is clear. My only thought was that maybe he is cranking down the water pump housing to tight (I learned when I met him not to try to do anything for him, cause his way is always right, so I just help with what he wants). Any thoughts as to why the driveshaft is binding on us? We compared the old pump with the new to make sure we were not installing it backwards...other than that...I am starting to love even more me trying to fit an engine in a car it wasn't designed for, it is seeming alot easier.

Thanks in advance for your help.

 

[splitshot]

Re: 1975 Johnson 70hp binding on start

havent heard of one binding like that...i know they are a little hard to turn with a new impeller but shouldnt be that hard...maybe you got the wrong impeller..if the impeller is all that you have to take off to get it to spin freely its somthing with the impeller...its not in gear is it ??

 

[Nomad767]

Re: 1975 Johnson 70hp binding on start

No, it is not in gear. After we did the water impeller, we changed the cables and I adjusted them to where it was in neutral everytime we moved it back from forward or reverse. Prop spins freely when we get ready to start it. We are possibly starting to lean towards the starter not having enough *** left to turn it, but it worked fine before the lower unit went. New starter is $270. It would be nice if we knew someone who had one around here that we could borrow to troubleshoot, but neither of us know anyone. We have even tried to pull start it while turning it with the electric start. We got it to sputter as we pulled it a couple of times, but it dies once we run out of string. We even bought a whole new water pump housing for it, but it changed nothing. He is about ready to shoot holes in the thing...lol. Had he not broke the impeller we pulled off of it, we would put that one back in since it was pretty much in good shape still. He can't afford to put it in the shop, and I hate it to be like everything else he has that is broke awaiting fixing....it sits there for about 5 years. I like to fish to much for him to do that...lol.

Oh, and yes we verified the water impeller about 5 times, and compared it with the old one about 3 times. The old one just showed a little wear on it, that was the only difference between the two.

 

[ob]

Re: 1975 Johnson 70hp binding on start

I am assuming that the starting battery is fully charged and strong and the starter cables are clean and tight.The added drive load of the waterpump during cranking could expose a weak battery or loose connection.

 

[Nomad767]

Re: 1975 Johnson 70hp binding on start

We have been keeping the battery on a trickle charge between the days we attempt, and we have even tried to jumper the positive side of the battery straight to the starter when he turned it over to bypass the cables. It did the same thing, we get about 1/4 turn on the motor and then it stops.

We even took his other battery out of the car I am putting an engine in, which had no problem starting my car, and get the same results.

 

[ob]

Re: 1975 Johnson 70hp binding on start

Sounds like the driveshaft length may be your binding problem with respect to the lower unit being an 80' and the engine being a 75'.Did the horizontal joint of the lower unit close up nicely once bolted in place?

 

[Nomad767]

Re: 1975 Johnson 70hp binding on start

hmmm...there was one slight difference on the driveshaft between the two lower units. The splines were straight on the old driveshaft, but the splines on this lower end had an L shape to them, do you think that the spline isn't going all the way up and catching on top of the L? The widest part of the L spline was the same width as the straight splines on the old lower unit, and the straight side of the L spline is towards rotation. It adds up to about 1/4 to 1/2 inch of distance, but the lower unit seems to go up just fine when we tighten it up. Other than that possibility I am leaning to the starter. I just hate to talk him into a $270 that might not fix it. I did find a used one for $50, but then again it is used and could give us the same problem.

I am just hoping that someone on here might think of something we may be missing.

 

[Faztbullet]

Re: 1975 Johnson 70hp binding on start

worn driveshaft

 

[Chinewalker]

Re: 1975 Johnson 70hp binding on start

You'll need to back up a bit - these lower units are not 100% interchangeable. This binding issue is a problem, but you'll find another issue, too. The 1980 lower unit shifts BACKWARDS from the 1975 unit. You will need the shift linkage from the powerhead of the 1980 model for the lower unit to work...

- Scott

 

[tashasdaddy]

Re: 1975 Johnson 70hp binding on start

1980 is a mechanical shift lower unit. the 1975 is a hydro-mechanical shift. the lowers are 2 different animals. shift linkages totally different.

 

[Faztbullet]

Re: 1975 Johnson 70hp binding on start

As Chinewalker says linkages are different but the splines are worn thus the L shape. The linkages wont make it bind.

 

[Nomad767]

Re: 1975 Johnson 70hp binding on start

Well, I don't know what we did, but it started great today. We put another battery on it, but I don't see how 20 more cranking amps would have made that much of a difference. Every other battery we used worked fine in anything else we put it in. We did clean all the contacts between the battery and the starter, but they all looked pretty good before we did it, just gave em all a quick brushing. Fired like a champ, adjusted the throttle cable and found we need to free up something in the controller, cause the throttle setting on the remote would stick up after you move it back to neutral. Tomorrow we plan to take it for a quick run regardless of the cold, rain, snow, or whatever the weather may hold. We are just dying to see how the new prop and pitch make her run. Thanks for the input guys.

 

[Silvertip]

Re: 1975 Johnson 70hp binding on start

Just because you used ONE jumper cable does not mean the NEGATIVE cable is OK. Installing a different battery likewise does not prove anything since you have not proven BOTH battery cables are good. Get out the second jumper cable and connect it between the neg terminal on the battery and the engine block (unpainted bolt or bracket). Then jump directly to the starter. Now if the starter doesn't spin you've eliminated the battery and cables.

 

[Nomad767]

Re: 1975 Johnson 70hp binding on start

Sorry, I didn't mention that, I did have the negative post grounded with the jumper cables to the engine. We are hoping it just had some bad connections and that we straightened them out by removing and cleaning the connections. It has sat for about 6 months since his lower unit died. As soon as we put it all back together and turned the key, it didn't hesitate a bit.

Tomorrow is gonna be a cold day on the water. But next weekend, its fishing time.