engine coupler smoked
 

toasted the engine coupler pulled drive and took a peek on the drive shaft appears to be in the coupler only 1 1/2" how far should it slide in ? it looks like there is about 1" of spline left in engine coupler wondering if the engine is to far forward,needs to be moved back 1" there was 1 1/2" worth of coupler on drive shaft any help would be great thanks

When a coupler blows up, 99% of the time, the rubber fails. The location of the input shaft from the drive has nothing to do with it. I dont know for sure how much of the splines are not into the coupler, but I would imagine about 1 to 1 1/2 inches is normal.

If you're getting it in an inch and a half that's plenty. We check it by putting fresh grease on the splines installing it then pulling it back out and see how much of the new grease is pushed.

Only way for the shaft to not enter the coupler is if your transom thickness is way over the Merc specs.
Motor bolts to the transom assembly, so that is a set dim.

thanks guys i guess we going for new coupler and not relocating engine

Firehawk,
The old style steel short hub coupler went up in price to about $800. The long steel snout is about half of that. But beware, some input shafts dont fit it and will almost bolt up. The drive will, as they tell me, be within an 1/8" - 1/4" of seating.
If you force it, it pushes on the crank and will destroy the motor in a short amount of time.
So check to make sure the new coupler will accept your input shaft.
If you have only two orings on the shaft, I am told it wont fit.

Hope that helps.
Dick

thanks for the info thats one less problem to fix with the engine placement

Damn, I so hope that isn't true. I just got 2 new ones and my input shafts only have 2 o-rings, is there anywhere I can check on this, there is nothing in the parts catalog about it.

Had a friend that found out the hard way, check it. Do u have the long steel hub?

Yes, I bought 2 new ones for my HP500s but I have the older input shafts. From what I am hearing the only difference is the older shaft doesn't have the 3rd o-ring to keep the grease in, no one seems to know about a bind issue.

Ted,
Merc engineers didnt know about it, until they were told of the problem. They may have corrected it by now, who knows. If your new couplers have the long snout, then check to see if the input shaft is hitting on the ID of the long snout. I was told the taper on the input shaft is different on the two oring verses the three oring.
Did you have trouble mounting the drives that last 1/4"?? If you did, then I would take them back off and check things. How long have you run the motors if at all?

This was something I did not know about and I doubt many others know either. Only way to know for sure is to slide the input shaft into the coupler and see how far it goes before there is interference. It must be taken off the ujoint to do it effectively.
Dick

Well as it turned out I had not mounted the drives till last night. I had a coupler with the extended snout on the shelf and a drive hanging on the hoist. The input shaft did not stop till it bottomed out. I also checked the gap at the shaft taper with it all the way in and there was about 1/8" between the parts. With a nice load of grease in there, the drives slid in like butter all the way, no fuss, no muss. The couplers were brand new and the shafts are first generation so there could not be more of a time split. So I guess they worked it out. Is there any chance your friend overpacked the coupler with grease and hydrolocked it in the front of the coupler?

what are the pro's and con's between hp coupler and standard coupler