mercruiser alpha 1 question

Hi all,
Having outdrive noise, and gimbal, u joints, splines all look good (great infact).
Any ideas where I should look next for the grinding noise?

Boat is out of water, running with muffs. Lower unit lube is fresh and full.

It's an older boat (1986) with a 140.3

Thanks

Re: mercruiser alpha 1 question

My advice is to never run it on muffs.
IF you do ,only idle it.

Mike

Re: mercruiser alpha 1 question

I only run it on muffs when I start it for the first time for the season, or when working on it. Always at idle, or very brief revs.

Re: mercruiser alpha 1 question

Check for play in the U-joints:

NOTE: Excessive side-to-side play in cross and
bearings can cause U-joint knocking. This condition
can sometimes be eliminated by installing a C-ring
Kit (P/N 53-12067). This kit contains 8 curved Crings.
These C-rings are used as standard equipment
on later production units. Curved C-rings CANNOT
be used with replacement cross and bearing
assembly P/N 41431.

http://www.boatfix.com/merc/Servmanl/6/6A3R3.PDF Go to page 17.

Re: mercruiser alpha 1 question

Thanks Johnnyboy,
U-joint are fine with no side play.
Think I'm gonna have to bite the bullet and take it to a pro.

Re: mercruiser alpha 1 question

Lundlubber2 said:

Thanks Johnnyboy,
U-joint are fine with no side play.
Think I'm gonna have to bite the bullet and take it to a pro.

Click to expand...

you havent really described the problem? grinding? does it change with shifting? could be out of adjust/failed shift cable,linkage etc. Sound like the clutch just barely rubbing up against the gear?

Re: mercruiser alpha 1 question

Does it make the noise only on the muffs or when in water too?? I have read when you do work on it it does make noise, not sure if its common, but have also read that sometimes you here noises while on muffs but not in the water.
Just trying to help

Re: mercruiser alpha 1 question

From my Mercruiser Shop Manual regarding stern drive units:

"If U joint noise is suspected, run the engine at idle. Have an assistant turn the stern drive first to port, then to starboard while you listen for noise at the gimbal housing. An unusual noise during this test indicates either u-joint wear or a defective gimble bearing."

Further in the chapter there is a chart:

Trouble: Drive shaft housing noise.

Probable causes:

• Low lubricant level - Add lubricant
• Worn/dirty u-join bearings - Clean/repair as required.
• Worn/dirty gimbal or transmission output bearing - Clean/repair as required.
• Contaminated Lubricant - Disassemble, clean, inspect and reassemble; fill with clean lubricant.
• Transom too thin - Shim transom plates
• Incorrect gear alignmet/shimming - Check and correct alignment/shimming.
• Worn, loose or damaged parts - Disassemble and replace parts as needed.
• Engine misaligned - Align with proper tools.
• Worn engine coupler - Replace coupler.

Not sure exactly what you have checked, but perhaps it is just misaligned slightly?

Re: mercruiser alpha 1 question

Thanks for the replies!! I couldn't find my original post... it got buried so fast!!

The boat is on the trailer, the trailer is on blocks keeping the tires off the ground. This boat hasn't been in the water for 2 seasons now, since I got the Lund. I keep fresh gas and lube in it and usually fog it because it sits.

The noise I heard sounded like a grinding or possibly rubbing? It was just at idle, or maybe a bit above, no turning or raising drive. I assumed it was the gimbal or u-joint and I didn't really run it long.

Being out of the water it's hard to pinpoint the noise due to the exhaust.

I plan on bolting the outdrive back up, checking lube, and putting it in the water to start it up. Maybe with a couple sets of extra ears, I can pinpoint the noise better. I will get an alignment tool and check that first!!


Thanks all for the ideas!
Bob

Re: mercruiser alpha 1 question

marinemike43 said:

My advice is to never run it on muffs.
IF you do ,only idle it.

Mike

Click to expand...

'There is absolutely NOTHING wrong with running on muffs. Make sure there is plenty of water pressure and volume. Merc recommends you keep the rpm below 1200 to 1500 rpm. Max, other wise you may overheat.


Did you have the outdrive down when running? While you have the drive off, I know you said the gimbal bearing LOOKED good, but did you actally turn it with your fingers to be sure it turned smooth? What the outsidel looks like is meaningless.

Re: mercruiser alpha 1 question

Thanks Don,
The outdrive was down all the way when I started it. I rotated the gimbal bearing by hand several times, and it was very smooth...no rough spots...consistent smooth rotation. I am going to check the alignment before I install it, maybe the mounts have sagged a tad.

I honestly didn't run it very long after I heard the noise...from all I've read on this forum in the past, I was sure it was a gimbal bearing noise. Maybe it still is?!

I'll get her in the water next week and run it a while, maybe it will give me more to go on.

Thanks again all!
Bob

Re: mercruiser alpha 1 question

I came across this thread while doing an Alpha 1 search. Bob's outdrive, situation, conditions and questions are identical to mine, with the exception of turning the gimbal prior to o/d install. Since my question is topical to this thread, I figured I'd ask w/out hijacking:
I too am concerned about a grumbling/rattling noise that I heard at an rpm slightly above idle, muffs on in neutral. I don't say "crunching" or "grinding" as it wasn't as consistent a noise as a bearing grind sound that I'm familiar with (automotive bearing issues).
Since I personally haven't checked the condition of the gimbal, and don't know its history (original/replacement?) I'm nervous about it.
What also makes me nervous is becoming stranded out at sea from an outdrive component failure. I've experienced Alpha 1 upper unit failure as a result of lack of oil. Very little warning, and a complete seize rendering necessitating a tow.
When gimbals are bad, do they go gradually with audible warning (louder & more constant grinding, for instance) giving you enough time to head back...or have they been known to lock up?
Thanks,
J.P.

Re: mercruiser alpha 1 question

I had just bought my boat, 1987 Invader 18 ft bowrider w/ 4.3 merc. and Alpha one gen one, and took it out a few times. It seemed strange that, when turning to either side, I could here a slight rumbling noise throughout the hull. Well, not knowing much about boats at the time, I didn't think much of it. I took her up to around 30mph and trimmed up. When I got back to the ramp, there was a bad vibration around the engine/ oudrive area. Took the boat home, pulled the plugs, and ran a compression test. It had 180 psi on all cylinders and very clean plugs. I put on the muffs and started up with the drive trimmed down. The vibration was not as bad, so I trimmed up a hair and it seemed to get worse. Time to pull the outdrive. I didn't see any leaks in the U-joint bellows, but there was water and some rust inside. The bearing seemed rough, but the U-joints seemed to move freely with no slack. I replaced the bearing and decided to replace the U-joints anyway since I was there. BTW, I did find a much easier way than what the manual says. When I took the U-joints apart, the needle bearings had very dirty grease. One U-joint cup was bone dry. It was a good thing I decided to do them even though they felt fine. My very long explanation has a point. If you are there, replace them anyway. You never know what you might find once the cups come off.