High RPM with no power…

[mrbrightside7]

I just got an old fishing boat that has a 1987 Evinrude 90 on it and I took it out for the first time today and I have a few questions on some things that I noticed that I hoped some of you could help me identify what the problems may be.

The engine fires up no problem, takes a couple of seconds of the starter turning when it’s cold, but once it’s warmed up, it fires up immediately. But once I put it in gear (forward or reverse), I hear a metal to metal clinking sound for about 2-3 seconds. Once the propeller is spinning at speed it doesn’t make the sound anymore, it seems to be once it clicks into gear. Any suggestions on what this may be?

Once I was going it seemed to run great at idle speed. I started to push the throttle and I found that I was giving it more and more power without much oomph. At max throttle I was only going maybe 10-15 mph. I kept it at max for about 30 seconds and the motor started to rev at a much higher RPM, but there was no power from it. It almost seemed to slow the boat down when it would rev up really high. Unfortunately there are no gauges on the boat, so I am not able to tell you what the RPM’s were at full throttle or when the engine revved up high. Are these symptoms indicative of any obvious problems?

Thank you so much for any help!

[dan-in-tn]

Its a little hard to say from your description. Let me give you some ideas and maybe you can explain more. First you may not be getting into gear properly. That would be the clinking noise you hear. Once you start to take off and the motor revs up do you feel it has popped out of gear? If you slow the motor down is it still pushing the boat at all? If it is then it is in gear and your prop hub may be spun. You can take the prop off and mark it between the hub and outside of prop. Run it again. If marks don’t stay lined up the hub has spun. You can have it re-hubbed at a prop shop. If you are jumping out of gear sometimes the shift cable can be adjusted. Depends on how long it has been jumping out. If I have forgotten anything I am sure someone will be along to help more.

Dan in TN

[frankr]

Dan pretty much said it all. The only thing I might add is the possibility of cavitation or ventilation. That is where air around the prop prevents it from getting a bite on the water. EDIT: Motor mounted too high on the transom??

The suggestion marking the hub is where I’d start. That probably is the culprit (spun hub).

The clattering when you shift it is not good. Are you shifting sharply and decisively? Being "gentle" with it is harmful and destructive, and certainly will cause $$$ problems in the future, if not already.

[mrbrightside7]

Thank you guys so much for this information. I will definitely be checking the hub to see if it has spun. Would I be able to get up to a speed of about 10 mph with a spun hub? Or would it only be idling speeds?

As for the gear shifting, I wouldn’t say I’m hesitant or soft with it, but I don’t jam it in. I guess I would equate how I do it to how I put my car into gear. I had no idea that being soft on it could cause damage so I will pay closer attention to how I’m shifting it and see if being more assertive keeps the clinging noise from happening.

[dave-bernard]

yes you could get some speed before it slips. and yes on the shifting.

[mrbrightside7]

I am trying to find the size of my prop, but it is not noted on the one I have. What size should I be looking to buy for this motor?

[dan-in-tn]

Impossible to say. When you take the prop off to mark it, if it is an OMC prop then the size should be on the hub. It is under the spline washer right around the circumference of the hole with the splines. On a V-4 should be like 13 3/4 X 15, 17, or 19? The last number is the pitch. Could be any pitch according to size and weight of boat. You need the proper prop so your boat with typical load turns the correct RPMs at WIde Open Throttle.
Do not shift your outboard like your car. One quick pop into gear is better with motor running. The water is your slipping medium. You don’t have a slipping clutch like a car.

Dan in TN

[jerry-ahrens]

Are you trimming the motor all the way in [down] before trying to get on plane? I guess first I should ask if you have power trim and tilt?

[Author]

Posts