If you did that you may have bent the tool. I tried doing one with a bent tool........didn't work

I rolled it across a flat piece of sheetmetal, and it rolled true.

Is it true that the coupler splines are aluminum? No wonder they wear out! I guess they are trying to save wear on the input shaft.

Yes, alum. If kept both greased and motor aligned, they'll last forever.

Do you have access to a machine shop that could turn you up a cheap and dirty plug to test fit into the coupler itself?


Also, best to remove the tool when messing with the engine adjustment. I've seen a transom assemble break at the bearing by not doing so.

Are you talking about something with splines on it, Jerry? If so, couldn't I just use the input shaft on the drive?

The burrs are on the very top of the splines - they do not extend into the grooves. Which is why I considered whether I could just deburr the inside of the coupler. Of course, even though the splines look pretty good, it does have close to 500 hours and ten years on it. My other concern is how much does the rubber fatigue over time?

i had a similar issue a few years ago.

I swore up and down that my tool was screwed up.

turns out the gimbal bearing, had got bumped just enough that it wouldn't let the tool slide all the way in. After I realized the gimbal bearing was cocked, and put it back straight, that tool went in. I adjusted the motor all over the place too, before I realized it.

I'm going to go ahead and yank the gimbal bearing tonight and replace it. Of course, that still doesn't solve my coupler issue. Anyone want to sound off on fixing a 500-hour coupler? It hurts damn bad to think about shelling out another $500 that I wasn't planning to spend on this thing.

http://www.cpperformance.com/c-278-drive-couplers.aspx

this is the coupler everyone here told me to run, its $349, better than $500!

to be honest i would have replaced it anyway, that $349 is well spent IMO than banking on a 500 hour coupler living long and having to pull the motor all over again just to replace that.

my coupler splines were toast, surprised they didnt snap off. funny part is the alignment tool fit it just fine, my guess is because the splines were so worn...

I'm feeeling your pain though with all the "surprises"...... i found out over the weekend that my oem intake bolts dont work on a rpm air gap intake, would be nice if they told me that in the instructions so i could have ordered the right bolts with the manifold instead of now wasting ANOTHER 4 days waiting for parts again.....

then i went to put my new gear on my distributor for my new cam, and gee guess what IT WONT FRIGGEN FIT... some dingbat at mercruiser drilled the hole for the alignment pin crooked... now i know why the old pin came out so hard since it was BENT in order to fit through the holes that dont line up... now i need to find a new dist shaft and they dont sell the shaft separate........

this motor is supposed to be on the dyno in 7 days, all these little surprises are putting a serious dent in that dyno session happening.. I'm about ready to put this boat back in storage as my frustration level is getting pretty high with all the little surprises... i can only imagine what else i fond once this motor gets back in the boat...

No, a plug the same OD as the tool. No splines. That'll let you know if the tool can go in at all. When a coupler starts to wear, the tips will be sharp and pointed from the tooth getting distorted, making the ID actually smaller, not allowing the tool to enter. You could knock off the burrs to get the tool to enter, but the input shaft does not locate on the tips of the splines, so that really isn't the best. And how would you know if you removed the burs evenly, not more on 1 side than the opposite? The ID is machined with the splines, making them concentric with the contact are of the splines, allowing the ID to be used for reference. I'd bet an input shaft would enter since that shaft has the root of it's spline tooth larger than the ID of the couple splines itself. Kinda hard to explain if you don't understand the makeup of teeth. Both the tips and root (bottom) of mating teeth of both coupler and input shaft do not make contact while running. They have built in clearances.

10 yrs and 500hrs, sharp teeth.... be best to bite the bullet and replace it now. Or replace it this summer when it's 100* out a the day before your big trip.

See if the tool will go in while the old bearing is out, before you put the new one in.

x2