2008 4.3L coupler

[dozerII]

I need a little help from the experts. A friend asked me to look at his 2008 18' Crestliner aluminum 4.3L mercruiser ser 1A316906 Alpha 1 ser 2CL77890. He is running a Quick Silver 5758 R13.3X19P 5 blade stainless prop. This past weekend he was in a Walleye tourney and was running across the lake at WOT when the engine rev's went way up so he pulled the throttle back. I checked the back of the flywheel cover and it is covered with sticky black rubber ooze, with the drive in forward you can turn the prop with some force and not turn the motor over, so the coupler is toast. So my question is there is absolutely no damage on the prop or the skeg, the gimbal bearing feels real smooth, what could take the coupler out? Is it over propped? Other than the coupler what should I look at replacing?
Thanks in advance for any and all help.

 

[HT32BSX115]

the coupler is toast. So my question is there is absolutely no damage on the prop or the skeg, the gimbal bearing feels real smooth, what could take the coupler out? Is it over propped? Other than the coupler what should I look at replacing?
Thanks in advance for any and all help.

Howdy,

Couplers usually fail because the alignment is "off" and/or the coupler hasn't been greased.....it's not always due to a prop strike.

Sometimes the rubber "donut" just fails. I have heard of a few that failed right out of the box.

Mercury recommends checking the alignment every year mainly to catch alignment "changes".

It can change because of either transom rot or engine mount rot which could cause the engine to move slightly.

That doesn't usually happen in newer boats.

If I'm not mistaken, that coupler fits many different engines up to the 5.7L V-8s. So that coupler is rated to work at a much higher torque than the 4.3L engine can dish out.

2008 is a pretty new boat so unless there was some early water intrusion into the transom or stringers/engine mounts etc, Since those types of problems causes a coupler to fail in the aluminum splines, and this one was in the rubber, it's possible that the coupler was just defective.

Regards,

Rick

 

[dozerII]

Thanks for the reply and the info Rick. This boat has been covered when ever it is not on the water, very dry inside and always on fresh water. I will change the coupler and check the alignment, I am thinking you are right the alignment is off quite a bit and took out the coupler.

 

[dozerII]

I believe I found the cause of the coupler failure, the bolts that hold the front mounts to the aluminum stringers in the boat are loose and you can see the port side mount has been walking left to right about 3/8". I will post some photos later.

 

[HT32BSX115]

I believe I found the cause of the coupler failure, the bolts that hold the front mounts to the aluminum stringers in the boat are loose and you can see the port side mount has been walking left to right about 3/8". I will post some photos later.

Eureka, I think you may have found it! Severe mis-alignment would probably stress the donut........

 

[dozerII]

Anyone have a link to the service manual for this motor?

 

[81 Checkmate]

Might find it in the Adult only (Sticky's) section .

 

[alldodge]

Coupler 18643A 5
Manual appears to be 26
http://www.maxumownersclub.com/foru...ice-Manual?s=9d50b7233b5227fa0c72717aae7f4677

 

[dozerII]

Might find it in the Adult only (Sticky's) section .

Thanks Checkmate I looked in there and the link would not go new enough.

Coupler 18643A 5
Manual appears to be 26
http://www.maxumownersclub.com/foru...ice-Manual?s=9d50b7233b5227fa0c72717aae7f4677

Thanks AllDodge.

As promised here are a couple photos of the mounts, out of the 8 bolts (4 for the cross member and 4 for the mounts) 7 were finger tight. As you can see the motor was sliding side to side quite a bit.

 

[81 Checkmate]

I guess there is another support under the Tee bracket coming off the alum channel

 

[dozerII]

I guess there is another support under the Tee bracket coming off the alum channel

That's correct Checkmate, 3 of the four bolts holding it in were loose as well.



And here's the kaput coupler, there has never been a grease gun on the nipple. Parts are on there way from Iboats.

 

[Bondo]

And here's the kaput coupler, there has never been a grease gun on the nipple. Parts are on there way from Iboats.

Ayuh,.... Simple Maintenance,....

 

[dozerII]

Ayuh,.... Simple Maintenance,....

Isn't that the truth, just as your signature says.

 

[Villain lll]

Thanks for sharing the pics Dozer. Kinda makes you want to go out and check your motor mounts ASAP.

 

[dozerII]

I would recommend anyone with a Crestliner change all the motor mounting nuts to a locking style as the regular style don't stay tight, go figure:facepalm:

 

[dozerII]

Okay experts I'm back with this Crestliner again, after only a few hours running time it lost the new coupler!!! The alignment was smooth as silk, lots of grease but smoked again according to the owner. He said he was running down the lake WOT and it was like it came out of gear, smelt burnt rubber and would not move the boat. He used his trolling motor till it went dead then fired up the engine again ant it would only turn the prop if it was tilted way up. Any ideas? I won't get to see it till the first week of Oct.