Grinding noise from power trim.

[AEROCOOK]

My 1987 Evinrude 90hp is making a grinding / rattling type noise when I trim up. The noise can only be heard when going up, down is normal. Also, once the motor is trimmed up/out to the point where the trailering motion takes over and the tilt moves faster, the noise goes away completely.
It seems to be the bottom 15 degrees going up that is noisy.
Any ideas?

 

[jonesg]

Re: Grinding noise from power trim.

an air pocket under huge compression can sound like that, try filling the reservoir and cycling up and down a few times, refill again.
It should quieten down.

 

[AEROCOOK]

Re: Grinding noise from power trim.

an air pocket under huge compression can sound like that, try filling the reservoir and cycling up and down a few times, refill again.
It should quieten down.

That sounds a lot cheaper than replacing parts!
I hope thats the problem, I will let you know how I make out.

 

[jonesg]

Re: Grinding noise from power trim.

a very high compression hydrolic system thats spitting air does sounds like grinding, I suppose it could be grinding but its usually just air.
Post back if it doesn't work, theres another thing you can try to move the air out.

 

[AEROCOOK]

Re: Grinding noise from power trim.

Do I have to use OMC power trim fluid or is there a suitable alternative?
If there is an alternative can it be mixed with the factory fluid or will I have to completely empty then refill?

 

[ezeke]

Re: Grinding noise from power trim.

GM Dextron II

 

[AEROCOOK]

Re: Grinding noise from power trim.

Okay, I filled the reservoir with dexron as per the instructions in the factory manual, it was a little low but not that much. I cycled the motor up and down 5 times and it was exhibiting the same noise the whole time. Removed the fill plug and checked the fluid level and it was good. I ran it up and down 5 more times and the noise was now noticable throughout the entire "up" stroke including the faster trailering motion which was quiet when I started.
I took the electric motor off to inspect the bearings and brushes and all was good.
So now I have another question or two...I had the motor on it's side when transporting it, could this have caused a problem? If there is air in the system, is there a more effective way to bleed it than just running it up and down?