Engine/Outdrive issue

[bigdog]

At the end of last season, I started to notice a problem with either my engine or outdrive, not sure where problem exists, and would like your feedback.

The problem is when I begin to accelerate from wake steed to full throttle,
the engine or outdrive vibrates very noticably. After I get 'up on plane'
the engine smooths out, and the vibration seems to disappear, at least you can't notice.

1995 4.3L Mercuiser. with Alpha-1 Drive

What do you think the problem is ?
Propellor looks good, no dings, but never had it tested for 'pitch' alignment.
I've heard that the 'gimble/joint' on outdrive could also create this issue?
Is there such a thing as outdrive being mis-aligned ?
Could a mis-firing engine cause this affect, and create initial vibration ?

Any feedback would be appreciated !

Thanks!

[Dave R]

If it's your gimbal bearing or U joints, it would do it when turned too. Does it?

Does it feel less powerful as well? A misfire could easily vibration under heavy load (like when you are transitioning onto plane. Plugs, wires, cap and rotor would be a good start, if it's been awhile since they were changed.

It is possible for the engine to be out af aligment with the drive. The alignment is supposed to be checked every 100 hours, if memory serves. Since the drive has to come off to check the aligment, the U joints and Gimbal bearing can be checked at the same time. It's also a great time to remove any corrosion, then prime and paint the bare parts of the drive.

[John A. Birdsall]

One of the points I would check is the rubber in the propellar. Seems to me I had that problem and in not too long the rubber on the propellar broke free, I still have not fixed the propellar, I just replaced it, and I have two propellars one is good one is not and they are not on the motor at present can't tell them apart.

[Dave R]

One of the points I would check is the rubber in the propellar. Seems to me I had that problem and in not too long the rubber on the propellar broke free, I still have not fixed the propellar, I just replaced it, and I have two propellars one is good one is not and they are not on the motor at present can't tell them apart.


Good point. Having solid props, I forgot about rubber prop hubs. It would slip under maximum engine torque.

[bigdog]

DaveR,

If memory serves me correct, the vibration problem doesn't seem to occur when turning.

It's been a while since I changed the plugs, wires, cap and rotor, but plan to do so in the Spring. Is there also a 'Condensor', in the distributor housing?

That being said, can I purchase these parts from my local Auto Parts store, or do I have to go a marine dealer and pay twice as much ! Is there any difference between my 4.2L Merc, versus the same engine in an automobile?


John
You mentioned 'rubber in the propellar', I'm not sure what you mean ?
I don't have any rubber on my prop ?
I have 2 props, and hey are both aluminum.

Thanks for the feedback, much appreciated !

Bigdog

[Dave R]

DaveR,

If memory serves me correct, the vibration problem doesn't seem to occur when turning.

It's been a while since I changed the plugs, wires, cap and rotor, but plan to do so in the Spring. Is there also a 'Condensor', in the distributor housing?

That being said, can I purchase these parts from my local Auto Parts store, or do I have to go a marine dealer and pay twice as much ! Is there any difference between my 4.2L Merc, versus the same engine in an automobile?


John
You mentioned 'rubber in the propellar', I'm not sure what you mean ?
I don't have any rubber on my prop ?
I have 2 props, and hey are both aluminum.

Thanks for the feedback, much appreciated !

Bigdog

Plugs are marine rated and made of stainless steel. I would think the cap and rotor would have to be marine rated as well, considering the sparks they deal with. Plug wires should be the same as a car. I doubt you have a points style ignition, therefore, there's probably no rotor. NAPA sells marine parts, BTW. That said, you can never go wrong with Mercruiser OEM stuff, it is well made.

Most Alpha props have a rubber coupling in the hub that helps prevent damage to the propshaft from rock strikes. It fits tightly between the splined inner section and the aluminum outer section. They can and do fail. I strongly suspect that's the culprit here. A prop shop can "re-hub" the prop for little money.

[bigdog]

DaveR,

Thanks for the info. regarding the engine parts, will keep in mind when replacing this Spring.

One question about this: If the distributor has a 'rotor', wouldn't it also have 'contact points' ? Maybe I'm dating myself ? In the 'old days', distributors always had 'contact points' which you had to set the 'gap'.
If there are no 'contact points' anymore, how does it now work ?

Not sure I undestand what you're referring about the 'rubber coupling' on the propellor ?

You said 'Most Alpha props have a rubber coupling in the hub that helps prevent damage to the propshaft'. Are you referring to the 'Forward Thrust Hub' ? See reference below.

See http://www.boatfix.com/merc/Servmanl/14/14a2.pdf
Page 24A (top picture) Propeller Without Flo-Torq II Drive Hub
Part B - Forward Thrust Hub

I was told, that if the 'Propellor Hub' is slipping, would cause full-throttle high RPM's, this is not the case. How can I actually tell if the 'hub' is bad ?

Last, this could be something as simple as the 'propellor 'pitch' being out of alignment ?

If anyone knows of companies who service/repair 'props', and would recommend, it would be appreicated.

Thanks everyone for the information.

[robmac]

Napa carries the parts you'll need,mercury does't manufacture ignition parts they buy them most of which are delco-remy.make sure you apply never seize to the threads of your spark plugs so they don't seize in the heads

[Wolfeboro_Baja]

bigdog, regarding service/repair of props, I've used H & H Propellor in Salem MA with excellent results! I dinged my Mercury stainless Mirage Plus prop and sent it down to H & H; when they were finished, you couldn't tell one blade had been bent and the other two dinged badly!! I think it ran better afterwards, too, but that's just my opinion, nothing scientific about it.

Here's a link to their webiste, http://www.hhprop.com/