Trim/Tilt knocking noise?

[vissertrades]

Hi,<br /><br />My '95 50 hp Johnson's trim/tilt developed a knocking noise on the down stroke only. I've checked the pins/bushings and they rotate freely. I operated the trim/tilt while it was not connected to the engine and the noise was still there. I checked the fluid while unit was vertical and that seems fine. I've bled the system per the manual and noise stops, but then re-appears when the trim motor cools down (10-15 min). This is driving me nutz!!!! Bleeding proceedure was to cycle up and down a minimum of 5 times while holding trim button on for 5-10 sec at each end of stroke. After 4-5 cycles the knocking noise just stops! Electric motor is warm to the touch. This noise just started when weather turned cold (40 or so). <br /><br />Any help before I bring it in to the shop would be great!

 

[vissertrades]

Re: Trim/Tilt knocking noise?

UPDATE!<br /><br />Boat is sitting in garage at 30 degrees. I heated TNT unit slightly with a hair drier and noise is gone. It will come back when it cools. Could this be a sticking down valve or the flow control piston? Should I even bother to have the dealer look at it?

 

[OBJ]

Re: Trim/Tilt knocking noise?

Piet....could you tell where the noise was coming from and does the motor "jerk" when the noise occurs?

 

[vissertrades]

Re: Trim/Tilt knocking noise?

It seems the be in the pump/valve body not the electric motor and operation is fairly smooth, not jerky. It only takes a little bit of heat, as with a blowdrier, to get the noise to stop. When it cools down past 40 or so it's right back to knock, knock, knock throughout the complete downstroke.