screeching sound?

[howard20138]

We are new to this boat it is a 1986 18' Bayliner with a 180 OMC inboard I am getting this horrible screeching sound if I adjust the trim while the boat is in gear and running about half throttle it will not stop unless I disengage and idle down. Does anyone have an idea as to the possible cause? Sincerely, Howard

[marshmat]

Hi Howard,

A 1986 Bayliner with a 180 hp OMC.... would that have the Cobra sterndrive?

The Cobra can be a bit loud on the trim adjustment, but a screeching noise is not normal. Provided you're staying within the normal trim range, and not trying to tilt the drive up to shallow-water position while it's running, my first suspicion would be the trim pump. If the pump's OK, my next thought would be the bearings on either side of the gimbal unit- unfortunately, anything in there is expensive to fix, and the parts are hard to find now.

Hopefully someone with more experience on this drive can chime in....

[PAR]

This might be the Cobra, but also could be another drive. If memory serves me the Cobra only has bushing on the gimble housing, with big bolts torque to over 200 pounds, noting to make that type of noise.

It's the trim system. Check fluid levels, check for leaks (the drive has to come off to change out the hydraulic lines), condition of cylinders, trim motor, pump, etc. You probably need some fluid, if you haven't burned up any thing yet.

The trim motor/pump assembly is located under the transom cover at the right rear as your looking at the engine from within the boat. It's easiest to get at with a small ladder from the port stern corner from outside the boat.

If it's an '86, then you should replace the exterior hydraulic lines (inside too would be best) , which will likely be leaking by now.

[howard20138]

This is a cobra drive, and that soounds possible thank's but can the pump continue to create noise even while the unit is stationary?Hi Howard,

A 1986 Bayliner with a 180 hp OMC.... would that have the Cobra sterndrive?

The Cobra can be a bit loud on the trim adjustment, but a screeching noise is not normal. Provided you're staying within the normal trim range, and not trying to tilt the drive up to shallow-water position while it's running, my first suspicion would be the trim pump. If the pump's OK, my next thought would be the bearings on either side of the gimbal unit- unfortunately, anything in there is expensive to fix, and the parts are hard to find now.

Hopefully someone with more experience on this drive can chime in....

[howard20138]

This is a cobra drive, and that sounds possible thank's but can the pump continue to create noise even while the unit is stationary?Hi Howard,


[QUOTE=PAR;263835]This might be the Cobra, but also could be another drive. If memory serves me the Cobra only has bushing on the gimble housing, with big bolts torque to over 200 pounds, noting to make that type of noise.

It's the trim system. Check fluid levels, check for leaks (the drive has to come off to change out the hydraulic lines), condition of cylinders, trim motor, pump, etc. You probably need some fluid, if you haven't burned up any thing yet.

The trim motor/pump assembly is located under the transom cover at the right rear as your looking at the engine from within the boat. It's easiest to get at with a small ladder from the port stern corner from outside the boat.

If it's an '86, then you should replace the exterior hydraulic lines (inside too would be best) , which will likely be leaking by now.

[howard20138]

This is a cobra drive, and that sounds possible thank's but can the pump continue to create noise even while the unit is stationary?[QUOTE=marshmat;263812]Hi Howard,

[PAR]

You could have a sticky switch(s). I'm fairly sure the limit switch (mounted on the drive) can't cause the pump to continuously run, so look at the control. If it's like most, it's mounted on the shift/throttle handle. Quite often these wires get chaffed or twisted up, inside the handle or more often where they exit and pass through the mechanism. Then again it could be just the bezel around the switch, not permitting it to return to the open position completely.

The shifter/throttle handle assembly is held by screws or through bolts (bolts likely) through the bolster on the sidedeck. Remove these fasteners and you'll be able to pull the mechanism out enough to get at the wires. Look for chaff, corrosion, etc.

These are fairly simple systems, both electrically and hydraulically. Figuring out what's wrong shouldn't take a lot of time or effort. If 12 VDC electrical or hydraulics aren't your cup of tea, then it might be best to have someone more familiar with these systems have a look.

A repair manual for your boat/drive combination is always a cheap and helpful resource, which will also out line these systems and their repair.

[howard20138]

Thank you very much for the input I'll check it out. Howard,