'78 evinrude 35hp not starting

[martysauer]

I thought that I needed a new prop because the boat would under load all of a sudden rev real high, yet slow down - so I replaced prop, and then it happened again, and I was thinking that I was slipping out of gear somehow. But as I was diagnosing the issue (while on the lake), eventually the engine started squealing (from the flywheel), and almost making a grinding noise and eventually wouldn't start back up. The flywheel almost feels hard to move at some points, and then it will seem to move freely, but I'm not hearing any pop from the valves (while the plugs are out) - in other words, at some points there seems to be no compression and then full compression. Could the issue be a woodruff key? If so, why the squealing (if you have a guess)?

Thanks,
Marty

 

[tashasdaddy]

Re: '78 evinrude 35hp not starting

drop the lower unit then turn the flywheel. if the head turns easily, the lower unit is shot, rebuild. there would be no compression with the plugs out, and the motor has reed valves, not moving valves like a 4 stroke motor.

 

[martysauer]

Re: '78 evinrude 35hp not starting

I understand how to check for compression, I just didn't write it clearly. What I'm saying is that it seems to vary between hearing the pop sound like it might actually be starting to then hearing nothing, which is why I was wondering if anyone has experienced anything like that with a sheared woodruff. I'd rather not pull the flywheel if it's definitely not the woodruff key.

 

[martysauer]

Re: '78 evinrude 35hp not starting

Anyone else have any ideas about this one? I am probably going to pull the flywheel this weekend, but I want to make sure I'm not chasing a red herring.

 

[samo_ott]

Re: '78 evinrude 35hp not starting

Any chance it was overheating?

 

[tashasdaddy]

Re: '78 evinrude 35hp not starting

pulling the flywheel is not bad.

 

[martysauer]

Re: '78 evinrude 35hp not starting

bump

 

[martysauer]

Re: '78 evinrude 35hp not starting

A big thank you to everyone who helped. I was able to get a local service station to use their air wrench on the flywheel nut, and the flywheel just popped right off, I put in the new flywheel key, and it started right up, I took it out on the lake yesterday and it ran like new!!! Couldn't have done it without the help I got here!!!

 

[67Johnson6HP]

Re: '78 evinrude 35hp not starting

Hope you torqued that flywheel nut!

 

[BoatBuoy]

Re: '78 evinrude 35hp not starting

To expand, if the key sheared, something caused it. Most likely the flywheel was not properly torqued to start with. I don't know about your '78 but the manual for my '77 specifies 100-105 ft/lb of torque. Your's is probably the same.

 

[martysauer]

Re: '78 evinrude 35hp not starting

Mine is the same. I tried to get the nut as tight as I could, but it's kind of a tough thing, because what are you supposed to hold while you tighten? I used a soft piece of 1x jammed in between the cavitation plate and the prop, is there something else people do? I was able to tighten it quite a bit, although I didn't use a torque wrench, so I can't give you a measurement.

As far as what made it shear in the first place, I honestly think that the engine is 30 years old, and things break - am I wrong?

 

[samo_ott]

Re: '78 evinrude 35hp not starting

The key should not just break on it's own. Even with age. Was the old key sheared off? Was it there at all?

They have flywheel straps to hold it when you tighten it. You need 2 people though.

If the flywheel popped right off on it's own when you took the nut off it really was bust and loose.

 

[martysauer]

Re: '78 evinrude 35hp not starting

Yes, it was sheared, I had to punch out the two halves from the cranshaft and the flywheel itself. I tried holding with a strap wrench(with help from a very strong person) and believe me, it wasn't happening. The manual says to use a flywheel holder for my particular motor (which I obviously didn't/don't have), and the strap wrench for smaller motors. I suppose I could put some locktite on top, but honestly the flywheel just doesn't seem to take much of a load to me, so it seems overkill to do that.

 

[BoatBuoy]

Re: '78 evinrude 35hp not starting

I was able to tighten it quite a bit, although I didn't use a torque wrench, so I can't give you a measurement.

As far as what made it shear in the first place, I honestly think that the engine is 30 years old, and things break - am I wrong?

Yep, in this case. The keys don't weaken with age. That flywheel was put on without proper torque. Sounds like you did the same and the chances are very good the same thing will happen.