would this be a bad gimbal bearing?

[jumpjets]

I just "de-winterized" my boat. Mind you, I'm a super novice boater, and pretty much everything I've done to the boat so far has been influenced by reading threads on this board.

It started right up, and idled fine. The gear shift works, as does almost all of the other systems on the boat. I do have one issue I'm worried about though: when I lay down on the deck to inspect the engine with it running, I can hear a disconserting noise from the rear of the engine. It sounds like a faint grinding noise with an occasional rattle.

I'll take a video of it and post it if that not a detailed enough description.

In the mean time, I think I'll grease the heck out of the bearing to see if it goes away.

 

[Brewman61]

Re: would this be a bad gimbal bearing?

Could be a few things. Coupler, gimbal bearing, something amiss in the drive. Might be a good idea to pull the drive and see.
Or at least let us know what happened when you greased the gimbal bearing. Careful poking around with a mechanics stethescope
might help isolat the noise.

 

[jumpjets]

Re: would this be a bad gimbal bearing?

I got a tube of quality grease, and greased all the fittings on the drive. I think I pumped half the tube into the the gimbal bearing grease fitting as well. How can you tell when that fitting is full? Where does the overflow come out?

The noise I was hearing did not go away, get any quieter, or change in any way. I put the drive in gear, and put it through its paces. I even ran it at 4k rpm for a short stint. The wierd noise I was hearing did not fluctuate with rpm. It did not fluctuate whether the drive was in gear or not.

I took a video of it, but the video sounds alot worse than how it sounds in real life. It's not worth posting.

So, in summary: I hear a slight noise that sounds like a bum sporadically shaking a tin can half full of nickels. It does not change with rpm, or gear selection, forward or reverse. It is completely independant of all changes in the drivetrain.

I'm beginning to think that the engine/drivetrain is just plain noisy. Is a 21 year old 5.7 merc/alpha 1 supposed to be silky smooth and ghost quiet, or is a noisy driveline the norm?

 

[90stingray]

Re: would this be a bad gimbal bearing?

You will not be able to see any squeeze out from the gimbal bearing... it's inside the large upper bellows. Go ahead and pull the drive to have a look and feel around. Check gimbal bearing and u joints. Takes a $8 gasket kit to pull the drive and will be about 20 mins for ya. Then you will know for sure.

 

[achris]

Re: would this be a bad gimbal bearing?

.... I can hear a disconserting noise from the rear of the engine. It sounds like a faint grinding noise with an occasional rattle....

Could be the exhaust shutters.... You didn't say what engine/drive/year you have...

Chris........

 

[jumpjets]

Re: would this be a bad gimbal bearing?

rog-o.

Two questions:

1) is that gasket kit available from west marine?

2) do you know of any informative, pitcure rich threads on how to pull a drive, before I start searching around for hours? I'm mechanically inclined, but this is my first boat project.

 

[jumpjets]

Re: would this be a bad gimbal bearing?

Could be the exhaust shutters.... You didn't say what engine/drive/year you have...

Chris........

sorry.

1990 wellcraft eclipse.
Mercruiser 5.7L alpha one

I would have to take pictures to give you more detail that that. Do you know of a good site/thread that explains exhaust shutter operation? Since the noise is independent of RPM, that actually makes alot of sense.

 

[rickryder]

Re: would this be a bad gimbal bearing?

You can find it here on iboats ...http://www.iboats.com/Mercruiser-St...4157116--**********.743487413--view_id.268710

Here is a link to the Merc factory repair manual.... http://www.4shared.com/document/Ak79wzYs/Mercruiser_Service_Manual_6_R_.htm

Might as well have the engine manual.... http://www.4shared.com/document/sxk6BBb0/Mercruiser_Service_Manual_15_1.htm:D

 

[rickryder]

Re: would this be a bad gimbal bearing?

a 21 year old 5.7 merc/alpha 1

You did....

 

[jumpjets]

Re: would this be a bad gimbal bearing?

thanks! I have the owners manuals, but these shop repair manuals are much better.

 

[achris]

Re: would this be a bad gimbal bearing?

sorry.

1990 wellcraft eclipse.
Mercruiser 5.7L alpha one

I would have to take pictures to give you more detail that that. Do you know of a good site/thread that explains exhaust shutter operation? Since the noise is independent of RPM, that actually makes alot of sense.

Exhaust shutters reduce (in theory) any water slopping back into the manifolds.

 

[achris]

Re: would this be a bad gimbal bearing?

You did....

Why is everybody picking on me??

 

[Joshua Nichols]

Re: would this be a bad gimbal bearing?

Whew I had a noise once.A awful sound had me freaking out a bit. Was thinking bad bearing or u joints.. Pulled the outdrive and started the engine up.. Still had the noise.. Turned out the exhaust was rubbing on the y pipe.. A pretty easy way to diagnose outdrive noise from engine noise.. Plus ya can grease the ujoints while you are in there..

 

[rickryder]

Re: would this be a bad gimbal bearing?

Why is everybody picking on me??

I wasn't pickin on ya mate! Just Sayin!
sometimes we miss the small print

 

[jumpjets]

Re: would this be a bad gimbal bearing?

This diagram makes soo much sense! I'm going to put a stethoscope up to that part of the exhaust to try and isolate the noise. I really think that the shutters are the culprit.

 

[achris]

Re: would this be a bad gimbal bearing?

This diagram makes soo much sense! ...

It's also in the service manual... Page 7D-2. (Service manual #15)

 

[BIGALF]

Re: would this be a bad gimbal bearing?

Stop doing anything until you pull your spark plugs. I just had the same sound and found 1 spark plug broke off inside the cylinder. It sounded like a coin in a tin can. I fished it out and changed all the plugs to find another broke off as it was pulled off.
How old are your spark plugs?

 

[jumpjets]

Re: would this be a bad gimbal bearing?

spark plugs are old, but I just pulled them and check them a couple months ago. This is the first time I've run the engine since then. I pulled the plugs to winterize the engine, and de-winterized and started it this past weekend. Due to the fact that the engine runs totally smoothly, I don't think it's a bad plug. It would missfire if it had a bad plug.

 

[cr2k]

Re: would this be a bad gimbal bearing?

Whew I had a noise once.A awful sound had me freaking out a bit. Was thinking bad bearing or u joints.. Pulled the outdrive and started the engine up.. Still had the noise.. Turned out the exhaust was rubbing on the y pipe.. A pretty easy way to diagnose outdrive noise from engine noise.. Plus ya can grease the ujoints while you are in there..

Turned out the exhaust was rubbing on the y pipe.?????? The Y-pipe IS the exhaust. please explain further.

 

[Joshua Nichols]

Re: would this be a bad gimbal bearing?

Turned out the exhaust was rubbing on the y pipe.?????? The Y-pipe IS the exhaust. please explain further.

Where the rubber boots meet each pipe.. Did a manifold replacement and got em too close together.. Made a awful noise..
Does that shed some light?