67 evinrude intermittent vibration

[cal1carifer]

Hi All,

Need some help with engine vibration, please. My 67 9.5 sportwin vibrates quite badly above about half throttle, but the virbration will come and go. It will vibrate for about 10 seconds, then stop for about the same period, then start again. It seems to be worst at full throttle. It pushes a 12' aluminium boat, usually with 2 men and fishing gear.

Is it most likely damaged, unbalanced prop? I dont know the engine history, but this seems to be an original prop (whether it is from this exact motor, I cant be sure). There are a few small nicks out of it, and the white paint is flaking off. I was going to pull it off, take it to a prop repairer and get their opinion on reworking, but it seems it might be cheaper and quicker to simply buy a replacement? I found an equivalent diameter and pitch prop in the iboats prop section; it looks different to the original, will it still perform the same?

What other problems could cause this type of vibration? The starts first pull, idles well, maintains revs, however it cannot plane the boat out. Not sure if this could be related to vibration, or merely a separate issue. Suggestions at this point would be greatly appreciated.

Ash

 

[cal1carifer]

Re: 67 evinrude intermittent vibration

Also wondering if it is OK to run it with this vibration, or am I possibly doing damage? I realise this will depend on the source of the vibration, but if it was the prop, what are the parts that would be most affected?

 

[cal1carifer]

Re: 67 evinrude intermittent vibration

Can anyone help me with some info on this problem please?

 

[Lion hunter]

Re: 67 evinrude intermittent vibration

I would say that your problem is likely a fuel or ignition issue do to the fact that the vibration is not consistent (i.e. 10 sec on the 10 sec off). Depending on the size of the nicks, if they are small I wouldn't worry to much about it, although a shop should be able to balance it, I would think a new prop for that small motor would be cheaper. When was the last time you rebuilt the carb, changed the fuel lines, adjusted points, new plugs, gear oil ect? I would do all your routine maintenance 1st since they always need it anyway and see if the problem still exists. Also when you check the points look over the flywheel to make sure the magnets are in place and it's torqued down properly.

 

[R.Johnson]

Re: 67 evinrude intermittent vibration

Try another prop. If that don't help, or you could check this first, is the flywheel tight? Vibration is not good on any engine. Something has to be loose, or mishapened.

 

[cal1carifer]

Re: 67 evinrude intermittent vibration

Thanks for the suggestions, the guy I bought it from claimed it had recently been rebuilt but that could mean anything and nothing I spose. I needed a fair bit of pressure on the flywheel puller to get it off, so would that have been tight enough? All I did was check coils so far, which look new. I did notice the fuel line from tank to engine had small air leaks in it, and have replaced that. Could an air leak in the fuel system cause vibration? I have a feeling it may have been enough to reduce top speed. I will go through the routine maintenance you suggested. In terms of trying a new prop, do the aftrmarket props made for these older engines work ok?

 

[R.Johnson]

Re: 67 evinrude intermittent vibration

I think we have some confusion here. Vibration, or loss of power due to possibly fuel, or ignition.

 

[Lion hunter]

Re: 67 evinrude intermittent vibration

Don't know about a vibration but it will cause surging and loss of power. The fuel pump is pulling from the tank, and any hole will allow it to pull air in. Usually when something is bent you will get a constant vibration at certain rpms. Since yours is intermitent I just guessing that its another issue beside prop. I would question the rebuild if they didn't even replace the fuel lines. I still leaning toward replace fuel lines, check flywheel magnets, replace plugs, check points and replace or regap and see where that gets you. If the points are good it'll only run you about $10 and it needs it.

 

[cal1carifer]

Re: 67 evinrude intermittent vibration

Sorry for the confusion, my issue is intermittent prop vibration which is worse at full throttle. I just mentioned my reduced speed in case it may be related somehow.

 

[cal1carifer]

Re: 67 evinrude intermittent vibration

Does anyone have any experience with the newer aftermarket props you can buy on iboats for these older motors? Although the the pitch and diameter are the same, they look very different from the original prop.

 

[Lion hunter]

Re: 67 evinrude intermittent vibration

I think you have to rely on the desription and not the pics. The props that are pictured have the right desription but the pic is of a larger through hub exhaust prop, which you do not have.

 

[ezeke]

Re: 67 evinrude intermittent vibration

The Michigan Wheel Propellers that will work on the 9.5 motors are:

012008 - 8.25 X 8 (3 blade)

012007 - 8.25 X 8.50 (3 blade)

012005 - 8 X 7.25 ( 2 blade)

Note that the 012007 may strike a hydrofoil if one is mounted on the A/V plate.

 

[F_R]

Re: 67 evinrude intermittent vibration

I have to wonder, did you or anybody else ever use a puller that grabs the outside diameter of the flywheel? That will damage (bend) the flywheel.

 

[cal1carifer]

Re: 67 evinrude intermittent vibration

Thanks very much all for the info. I noticed my fuel line from fuel tank to engine had a small leak in it so decided to replace this first. I took it for a test drive after that and I was blown away to discover all engine vibration was gone, and the top speed was much higher. The engne can now
plane te boat out. I hadn't had time yet to do any of yor other recommendations, so am fairly sure the replacement of the fuel line caused the improvement. I was surprised the fuel line could cause vibration, but am very happy the fix was this easy and cheap. Thanks again for your help, the prop should probably be replaced anyway, so I will still make use of the info.

 

[Lion hunter]

Re: 67 evinrude intermittent vibration

I have found over the years that 99.9999999% of the motors that I have bought used need about $75 worth of supplies when I bring them home. Fuel lines (everything that is rubber from the tank to the carb), points, plugs, carb kit and impellers. I used to monkey around and troubleshoot things to find that a simple fix could have been had days ago. Now I just make it standard practice whether it needs it or not. I have read countless posts where people were upset with their mechanic because he replaced all these things and added $100 to their bill when it didn't need it, or wasn't the problem. They fail to realize the money their saving in troubleshooting hours by replacing maintenance items. It saves a lot of headache. Glad it all worked out enjoy the boat and happy fishing.