35/25

I recently pulled one of my engines out for repairs ('99 HP500's). In the process I noticed that the splines on the coupler are worn down to points and the grease inside the hub is dry and caked. The coupler has 230 hours, and was greased about 55 hours ago. I bought the boat used with 115 hours on it and do not know how often the couplers were greased in the past.
I know that the two causes of coupler failure are bad alignment or lack of grease. My motors have the Merc HP motor plate mounts in front which are not adjustable, so I am hoping the alignment is ok. I have had the drives off a few times and they seem to slide in OK when I reinstall them.

I am trying to determine if this coupler wore out due to an alignment problem or if it was not lubed often enough in the past. Can you tell by the way the spline teeth are worn as to the cause?

I ordered a new coupler from Teague and they think it was lack of grease, but at the same time said that 230 hours on a coupler was pretty good life. My previous boat was a 271 Formula with over 550 horsepower. The coupler had over 400 hours and the splines still look great.

Trippin

Alignment is critical in an HP application. Lateral and horizontal positioning are a relative issue. Most marine Techs and service facilities will just assume that since the alignment tool slides in and out smoothly that the job is complete. Install the outdrive and send the customer on his/her way. Not so with performance applications. You can get away way with that mentality in small fish and ski boats but not larger heavier applications.

While lube is an essential ingredient in longevity of any marine part it plays a minor role in spline positioning. Postioning is determined solely by gimbal bearing reference and motor mount height, all other mounts are fixed, unless custom fabricated.

My suggestion to you is to find an alignment tool and perform the "dirty grease test". This test is where you insert the alignment tool with a heavy application of fresh drive lube grease then remove the alignment tool quickly and smoothly. The imprint on the end of the spline tool will show you which part of the Gimbal bearing is causing you the most resistance and accordingly binding the coupler splines. Adjust the engine so as to relieve this stress and free the coupler from unnecessary wear. A slight lateral or horizontal adjustment may be all that is necessary to alleviate the coupler wear problem.

I realize that your mounts are fixed. You should modify them in such a manner as to accomodate the aforementioned adjustments if necessary, otherwise your problems will persist.

Tinkerer

ONE IMPORTANT NOTE

The alignment tool must be easily installed with two fingers in or out.
If you have to fight it then it is not aligned.

The first time it goes in it may require a small amount of effort but after that it should be real easy to remove.

Mr Gadgets

and if the coupler hub is not centered then you can fight it all day. Get it lined up and then rotate the motor 180 degrees, see if things change.


Good luck

35/25

Thanks everyone.
I tried installing the alignment tool and it would only go in about half way, then stop. It was then hard to pull out. The grease pattern from the spline teeth was only showing on the bottom of the tool. I removed the front mount bolts and raised the motor a little at a time. After raising nearly a quarter inch, the tool slipped in easily and the grease pattern was all the way around the tool, but still more prominent on the bottom. As I raised the engine even more, the pattern started to shift more to the right (stb) side of the tool. Does this mean the engine is actually off laterally a little bit?

I will have to enlarge the holes in the L angle brackets, unless I try to put new brackets on and start fresh. If I simply enlarge the holes, will the motor stay put if you tighten the bolts real good. Or how about drilling another small hole on each side and installing a dowl pin to keep the motor from shifting?

Mbam

Either start over or dowel, it will not stay put otherwise. Yes it does sound like it is moving sideways also.