Could engine coupler need replaced after only 40 hours?

[olddogmike]

I replaced my engine coupler in May and now, after only 40 hours on the water the engine rpm's are climbing and speed is falling off again. I did purchase and use the alignment tool. The tool went through the gimbal and into the coupler with no problem. The outdrive slid into place and faced up on the transom without a fuss. I noticed that the engine seems to surge at around 3200 rpm and then loses speed as the rpm's climb past the 3500 marker. I am wondering if there could be something in the outdrive that could be the cause of this problem. Could a fouled bottom or lower unit contribute to this? As always, much obliged for your input.<br />Thanks to all.

 

[Laddies]

Re: Could engine coupler need replaced after only 40 hours?

Ck the slip hub in your prop, but it is possable for a coupler to fail

 

[rodbolt]

Re: Could engine coupler need replaced after only 40 hours?

never seen a coupler slipp more than once, usually once slipping it melts the rubber but I guess its possible, paint the aft end of the coupler and shaft with fingernail polish or the like and see if the marks move apart

 

[seahorse5]

Re: Could engine coupler need replaced after only 40 hours?

A weak transom can affect coupler life as it "gives" during acceleration and the alignment changes, putting a strain on the coupler rubber.

 

[rodbolt]

Re: Could engine coupler need replaced after only 40 hours?

but usually once the coupler rubber spins the heat generated will make a lot of rubber smoke and the coupler fails rapidly. but like seahorse says, weak transoms kill a bunch of couplers, as will weak engine supports. the fwd thrust of the propshaft on a non stringer unit is taken by the transom and the engine mounts just take the counter rotational thrust from engine torque. any weakness in the mounts or transome will distort shaft alignment. when you say speed falls off about 3500, is that hull speed or engine speed ?

 

[olddogmike]

Re: Could engine coupler need replaced after only 40 hours?

thanks rodbolt, seahorse and laddies; the hull speed falls off. engine rpm increases, speed drops. I just took the boat out this morning and it began to increase rpms and drop speed at about 3200 rpm. Droped to trolling speed and trolled for 2 hours. On the way back into the creek I increased speed and lo and behold, no problem.<br />I have pulled the boat to inspect the prop and the outdrive and bottom. Although there appears to be plenty of outdrive oil could low outdrive oil level or foaming cause similar symptoms?<br />Thanks again for the help.

 

[WillyBWright]

Re: Could engine coupler need replaced after only 40 hours?

No. It wouldn't have gotten better. It would've gotten worse. If the problem suddenly disappeard, my vote if for weeds on the prop.

 

[olddogmike]

Re: Could engine coupler need replaced after only 40 hours?

Thanks WillyBWright, you may be on to something.<br />While I was trolling I backed the boat down for about 2 minuets. It was after that when I headed in and the boat ran as advertised. Went out again this evening after checking outdrive oil and everything seems squared away. Thanks to all for the help. Best regards.

 

[Richard Petersen]

Re: Could engine coupler need replaced after only 40 hours?

Hope it was weeds. Not rope or something that could wedge up against the prop shaft seal and have ruined it. I would have the seal checked VERY closely. Hope you are lucky.

 

[olddogmike]

Re: Could engine coupler need replaced after only 40 hours?

Thanks cyclops2, I will pull the prop and check the seal closely as you have suggested.