how do you tell if you have a Prop Hub problem or Coupler problem

mark_fitzy

Petty Officer 2nd Class
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I am having sliping problems with my Mercruiser Alpha 1 V6

I dropped the boat into the mechanic yesterday , Question is am I having Prop problems or Coupler problems.

I just got a call from the mechanic, he tells me that I have a FLO-TORQ hub style prop. which means I think that if it is the prop that is sliping it would mean that the Prop Hub seal breaks away , Hard Plastic. He said its either broken or its not, apparently it dosent wear.After inspecting the prop he said there is no broken bits, no wear at all and he couldnt stop the prop from turning when he put it under pressure (out of the water)So he is saying he thinks it is the Coupler (rubber Donut),

He said he is going to take the boat down and put it into the water to make sure,. My question is this! How do you tell if its the coupler or the prop causing the problem in the water? Does it slip differently or will he smell burning rubber????
 

captmello

Captain
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3,849
Re: how do you tell if you have a Prop Hub problem or Coupler problem

If he can get it to slip in the water rank, He can try a different prop to see if it still slips. If it still slips with a new prop, coupler time.
 

mark_fitzy

Petty Officer 2nd Class
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Re: how do you tell if you have a Prop Hub problem or Coupler problem

He told me(the Mechanic) he is certain that it isnt the prop so he is going to put into the water and try and re create what I was telling him (re when I get up to speed the gear slips and revs high)

im trying to work out if there is a way of telling if its the Prop or the Coupler if you DONT put another prop on the boat when running it in the water.
 

ziggy

Admiral
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7,473
Re: how do you tell if you have a Prop Hub problem or Coupler problem

ya can scribe a line on the prop shaft and prop. go run it. if these lines no longer are mating lines after the run. the prop hub has slipped....
 

JustJason

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Re: how do you tell if you have a Prop Hub problem or Coupler problem

if it's the coupler usually the bilge is full of burnt rubbery bits.
 

AZSenza

Chief Petty Officer
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Mar 11, 2008
Messages
521
Re: how do you tell if you have a Prop Hub problem or Coupler problem

I Always paint a small line on things that can slip, that way its easy to tell if it ever feels like it. I also paint them on important nuts, like prop nuts! so I can see if its backing off.
 

billbayliner

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Re: how do you tell if you have a Prop Hub problem or Coupler problem

Well if it is the coupler a sign is the engine will over heat as the cooling pump will not be working.
 

Don S

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Re: how do you tell if you have a Prop Hub problem or Coupler problem

Well if it is the coupler a sign is the engine will over heat as the cooling pump will not be working.

That's wrong, we just went thru this in his other post.

There are 2 ways for a coupler to fail. If the metal splines in the coupler spin out, then the water pump will not turn. but the boat will also not move at all.

Now, if the rubber hub of the coupler breaks loose from the splined portion of the coupler the pump still turns and like a prop the boat will work fine at low speeds but when you try to go fast it slips. That's when the rubber pieces can fall out and you can smell smoke. (Possibly) with a good vent system, you may not.
 

mark_fitzy

Petty Officer 2nd Class
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Re: how do you tell if you have a Prop Hub problem or Coupler problem

Hi Don
I know we covered this in the last post, and I understand what you are saying. But Im confused to why the mechanic has to take the boay out in the water. He said he wants to know for sure what the problems is, He said he is pretty sure it is not the prop because there is no damage.

My question is this, How will he tell from driving the boat on the water if its the prop or the coupler?
 

Don S

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Re: how do you tell if you have a Prop Hub problem or Coupler problem

He probably wants to VERIFY the problem is the coupler before removing the engine to replace it and find it LOOKs ok. You would get all POed if you payed for a new coupler and it wasn't the problem, wouldn't you.
Basically without any troubleshooting, all anyone can do is either take a guess or troubleshoot it.
 

mark_fitzy

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Re: how do you tell if you have a Prop Hub problem or Coupler problem

Totally understand Don, just was wondering if there was a way of telling if it was the Prop or the coupler just be driving it.

I believe the engine comes out to replace the coupler but does the leg have to come off as well?

Just wondering what else I should get him to do while he is taking the engine out.
 

Don S

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Re: how do you tell if you have a Prop Hub problem or Coupler problem

I believe the engine comes out to replace the coupler but does the leg have to come off as well?

Yes the drive has to come off. It should be removed yearly to check the alignment. A seriously out of alignment engine due to a faulty engine mount will cause the hub on the coupler to seperate from the rubber.
Definityl have him install new rear mounts while it's out. When they get soft or seperate they allow the back of the engine to drop and cause the couplers to go.
They require an engine pull also, might as well do it once and not twice.
 

mark_fitzy

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Re: how do you tell if you have a Prop Hub problem or Coupler problem

Hey Don
Sorry to be ignorant but what is engine pull never heard of that term...
 

Don S

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Re: how do you tell if you have a Prop Hub problem or Coupler problem

Engine pull = remove engine from boat.
 

mark_fitzy

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Feb 14, 2009
Messages
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Re: how do you tell if you have a Prop Hub problem or Coupler problem

Now I feel like a real idiot...bit slow us guys from down under lol

I was thinking, while he doing all that work, should I just get an
oil change,
new impellor

along with the new coupler and rear engine mounts

anything else I should get serviced while its out?

Thanks Mate
 

Don S

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Re: how do you tell if you have a Prop Hub problem or Coupler problem

When I pull an engine for any reason. I look at everything that you can't get to with the engine in the boat.
Pumps, wiring, blower hose, bilge pump hose, etc. etc.
Then clean everything. Paint it if you want.
If it's a pain to do with the engine in the boat. Well, the engine will be out.
Nows the time to fix it.
 
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