Trim making terrible noise. Motor mounted too low?

[pilldok]

I have a 2001 Optimax 150 whose trim is sounding terrible when lowering the motor. The sound is normal when trimming up. I've ordered a replacement trim motor and hope that cures the problem. I've had the boat since new and this motor has been mounted in this position since purchase. While examining the trim mechanism I noticed that the lower portion of the lower piston guide assemblies were slightly below water level. Should these not be above water level? Has the motor been mounted too low since purchase? Seems to me that in this position the threat of water penetration would be great in the piston assemblies. The boat sits in the water year round in a slip not on a lift evident by the corrosion in the photo. Any help with that trim noise would be appreciated too. Thanks!

 

[James R]

Probably air in the system and /or oil level low. Bring the motor up to the high position and apply the latch. Remove the fill plug which you see in the photo and squirt fresh oil in until it dribbles out then replace the plug. If oil dribbles out when you pull the plug just put the plug back in and exercise the T/T to remove the air. If this doesnt work then a teardown will be needed. These systems can work submerged without problem.

 

[Texasmark]

Probably air in the system and /or oil level low. Bring the motor up to the high position and apply the latch. Remove the fill plug which you see in the photo and squirt fresh oil in until it dribbles out then replace the plug. If oil dribbles out when you pull the plug just put the plug back in and exercise the T/T to remove the air. If this doesnt work then a teardown will be needed. These systems can work submerged without problem.

The only reason I wouldn't support this answer is the direction. Max pressure is up so any any air would/should be more noticeable under the highest load. Butttt.

On mounting too low, if your hull has dead rise (deep V hull) at the transom you have no choice other than to have bought a boat with a longer shaft engine sitting on a higher transom bracket.

Usually the AV plate, the horizontal plate just above the prop, is even with the hull when trimmed vertical to the hull or slightly above or below....depending on the hull and usage.

On burping as James suggested, after filling the reservoir to the top of the threads where you pulled out the plug and reinserting the plug, run the trim to max up and max down listening for a reduction in the cavitation caused by air. If it reduces continue till it quits.....dozen or so trips may be necessary, max up to max down, etc.......

 

[pilldok]

Thanks for your help!

 

[Chris1956]

What is the height of your transom? It should be 20" or more. Normally only the very bottom of the PTT unit, where the zinc anode is would sit in the water.

Is your boat rated for that motor HP?

 

[pilldok]

Thanks for your help but I have found the culprit. It was the trim motor. I finally got the boat out of the water and replaced. I would have never believed that it could have made the loud screaming sound I was hearing but I guess since the boat is a tri-toon the sound resonated thru the hollow toon the motor is mounted to. Thanks again for your input.