Cobra drive noise

[Donzi GT250]

Can a impeller in a Cobra drive make a medium to high pitch howling noise?
I am getting a howling noise from my 1989 5.7 Cobra drive at 3000 rpm and above.
I guess it could be a gimbal or some other bearing or even gear noise, but I was thinking of looking at the simple stuff first.
The impeller was changed about 80 hours ago or almost exactly one year ago so it isn't new but not real old.
Also the gear lube was changed 60 hours ago and i am using the the Evinrude HPF XR high performance gear lube and I took a look at the lube a month ago and the level and color where good.
Any ideas?

 

[sea wolf]

Re: Cobra drive noise

Never heard of an impeller making any noise, period. Does that gear lube you're using have a GL rating?

 

[Donzi GT250]

Re: Cobra drive noise

The gear lube I am using is indicated for drives that required OMC Hi Vis lube so it should be what is needed in my drive.

http://www.bwbmag.com/output.cfm?id=1891729

 

[sethjon]

Re: Cobra drive noise

The noise is most likely the gimbal or u-joints. If you are sure you hear noise from the OD thats not good and must be pulled and checked. Does it happen all the time? when turning? slow and fast?

 

[Donzi GT250]

Re: Cobra drive noise

Just recently (one month ago) had the u joints replaced and the gimbal bearing checked and lubed.
Noise is mostly from 3000 rpm to around 3500 rpm. Could be making the noise at higher rpm's but I can't hear it possibly because of the addition engine and water noise.
Makes the noise when going straight or turning, doesn't seem to matter.
And I am sure it is from the drive area as I hear it coming from under the swim platform while underway.

 

[sethjon]

Re: Cobra drive noise

Just recently (one month ago) had the u joints replaced and the gimbal bearing checked and lubed.
Noise is mostly from 3000 rpm to around 3500 rpm. Could be making the noise at higher rpm's but I can't hear it possibly because of the addition engine and water noise.
Makes the noise when going straight or turning, doesn't seem to matter.
And I am sure it is from the drive area as I hear it coming from under the swim platform while underway.

When was the gimbal or ujoints replaced? Have you greased them lately? To find out you will have to pull the drive.

 

[Donzi GT250]

Re: Cobra drive noise

Thanks for the reply, but did you read the post you quoted?

When was the gimbal or ujoints replaced? Have you greased them lately? To find out you will have to pull the drive.

 

[bruceb58]

Re: Cobra drive noise

When you run the drive on the muffs do you hear the same sound at various RPMs? Also try it in gear but be very careful with people around the prop. With neutral, everything in the upper unit is still spinning but the problem is it isn't under load. When you run it in neutral, turn the drive full left and right to see if any noise gets louder. I know you said you replaced the u-joints but you never know if a roller pin fell over while putting on the caps.

 

[Donzi GT250]

Re: Cobra drive noise

No I don't hear the same noise when on muffs (although I will only go up to 1000 rpm without load) , in neutral no noise when turning wheel right and left full.