Mercuiser #1 Drive Ratcheting Noise

[haulnazz15]

Well, the perfect day for boating occurred on Sunday, unfortunately we barely got the boat off of the trailer. After idling from the ramp, the boat was given moderate throttle to get on plane, and within 4-5 seconds a loud bang occurred. At first, we thought we had hit something from the jolt, but no damage was found upon later inspection of the drive/prop. The boat would no longer go into forward gear, and was making an audible ratcheting sound coming from the outdrive while at idle, which increased in frequency when the engine is revved. The sound is louder when the outdrive is tilted up, but that could mean u-joints or possible lower unit closer to the surface. I then proceeded to "rig" the shift cable to get it into forward gear, which I was able to do with the engine off. However, when the engine is running, the drive refuses to go into gear, so we put it back on the trailer and towed it home. I found an video which shows the exact noise we were experiencing.

http://youtu.be/s2ff1O3nda8

Once at home, I checked the gear lube level (it was full), and pulled the top cover on the upper unit to inspect the upper gears. The gear 4-5 teeth I could see (due to full of lube) looks clean and sharp, with the fluid looking brand new dark blue-green. So long story short, what is the diagnosis?

I figured it was one of two options: u-joints, or lower unit gears/clutch failure. It is a 35 yr old unit, but the upper unit looks great. The only way to find out about the u-joints is obviously to pull the drive, but I would wait until we winterized the boat to check that out.

Ford 351w - 233 Drive (#1 Drive)

 

[Bondo]

Re: Mercuiser #1 Drive Ratcheting Noise

I figured it was one of two options: u-joints, or lower unit gears/clutch failure. It is a 35 yr old unit, but the upper unit looks great. The only way to find out about the u-joints is obviously to pull the drive, but I would wait until we winterized the boat to check that out.

Ayuh,... Drainin' some of the oil, might show metal,....

'n yer only 8 nuts away from seein' what's broken,... I'd pull it Now to see what's up...

Winterizin' is irrelevant at this point...

Is it pumpin' water,..??

 

[ziggy]

Re: Mercuiser #1 Drive Ratcheting Noise

granted, i'm no pro. but to me, that sounds a lot like a boat that's shifting, but hasn't quite gone into gear.

or lower unit gears/clutch failure

i believe i'd have the drive off too for some inspections. starting with gear lub inspection seems like a great place to start too.
maybe see if it shifts statically on land. ya know
fwd=prop locks ccw, ratchets cw
neu=prop spins freely w/o sound or feel
rev=prop locks cw, ratchets ccw
myself, i think i'd be listening to the ratcheting cw when in fwd too. ya know, as the gear teeth ride up ea. others ramps then fall off to the next tooth. while i've never had a lower apart, i'd think that if the gear teeth wore down there wouldn't be much ratcheting sound going on.
surly with a loud bang, then failure, there would be some tell tale as to what failed.
one good thing. at least a drive is pure mechanical. ya don't have to work with elec. that ya can't see or circuit boards ya don't understand what they do. that's me though..
good luck.

 

[haulnazz15]

Re: Mercuiser #1 Drive Ratcheting Noise

I may not have expressed it clearly, but when the static shift test is performed, it will go into fwd and reverse, and spins freely in neutral. So the actual shift function is retained when the engine isn't running. Well, winterization isn't quite irrelevant because the engine still needs to be fogged/fuel stabilized/etc before I take the drive off, else I get no cooling water from the muffs. I don't intend on using the boat any more this year if I end up having to remove the drive.

I don't know if water is still being pumped but the engine never overheated. It wasn't running for more than 4-5 minutes after the problem occurred, and hadn't been running for more than 2-3 minutes before it happened.

Note: new shift cable/gimbal bearing/etc all done within the last year, and showed no signs of issue all summer (at least 5-6 trips, over 3hrs each).

 

[Bondo]

Re: Mercuiser #1 Drive Ratcheting Noise

I may not have expressed it clearly, but when the static shift test is performed, it will go into fwd and reverse, and spins freely in neutral. So the actual shift function is retained when the engine isn't running. Well, winterization isn't quite irrelevant because the engine still needs to be fogged/fuel stabilized/etc before I take the drive off, else I get no cooling water from the muffs. I don't intend on using the boat any more this year if I end up having to remove the drive.

I don't know if water is still being pumped but the engine never overheated. It wasn't running for more than 4-5 minutes after the problem occurred, and hadn't been running for more than 2-3 minutes before it happened.

Note: new shift cable/gimbal bearing/etc all done within the last year, and showed no signs of issue all summer (at least 5-6 trips, over 3hrs each).

Ayuh,... Hook the hose to the in-comin' line at the T-stat housing....
or attach it into the gimbel housing...

If the shaft broke above the impeller, it ain't gonna pump water into the motor either....

 

[ktbarrentine]

Re: Mercuiser #1 Drive Ratcheting Noise

I may not have expressed it clearly, but when the static shift test is performed, it will go into fwd and reverse, and spins freely in neutral. .

I'd still like to hear more about the static shift check... Yes, you may be able to shift it to fwd and rev, but what is the response when you try to rotate the prop by hand with it in fwd and rev (like ziggy was explaining). If you get any sort of abnormal indication from that check, I think it is then time to explore the insides of the lower drive. If you can turn the prop by hand (with some resistance) CCW while in fwd, then your are disconnected from the engine. I dont think that is the case here, but would like to hear your results.

Pull the drive....5 minutes!!

 

[haulnazz15]

Re: Mercuiser #1 Drive Ratcheting Noise

I'd still like to hear more about the static shift check...

Static shift check was fine, meaning it locked the prop when in fwd so that it would not spin CCW, vice versa for Reverse. Spun freely with no noise in neutral. That was my first check when this happened, so I verified the prop was locking with boat still in the water. Also re-verified once we got it home.

 

[haulnazz15]

Re: Mercuiser #1 Drive Ratcheting Noise

Ayuh,... Hook the hose to the in-comin' line at the T-stat housing....
or attach it into the gimbel housing...

If the shaft broke above the impeller, it ain't gonna pump water into the motor either....

Understood, but I don't have the fitting to attach the hole to the gimbal, and it seems like it would be evident after 10 seconds on muffs if the water was flowing through the outdrive/engine. I would imagine it will be easier to hear the origin of the noise with it on the trailer as well. I will like be pulling the outdrive no matter what, but I figured I could just winterize the engine, then pull the drive off to inspect the u-joints and drain the oil for metal.

Also not of any likely importance, I had purchsed a new 15x16p 4-blade prop which was installed prior to this trip. I can't imagine it was of any consequence though.

 

[jackd1023]

Re: Mercuiser #1 Drive Ratcheting Noise

Just jumping in with a theory, sounds like a broken U joint. PULL DRIVE

 

[haulnazz15]

Re: Mercuiser #1 Drive Ratcheting Noise

Okay, so here's an update w/video. I winterized the boat this weekend, and recorded a video at idle, in neutral, of the noise coming from the drive. I verified that the prop was free-spinning with no resistance in either direction, and no noise in either direction when turned by hand prior to the engine start, so it doesn't appear to be a cable-adjustment issue. The drive would go into both forward and reverse while on the trailer, but a lot of chatter when going into forward until it locked in gear. I drained around 3 measuring cups full of lubricant from the drive after shut down, and found no metal shavings, as well as pulled the top cover to view the exposed upper gear set again and found nothing but razor sharp gear teeth.

http://s2.photobucket.com/albums/y14/Haulnazz15/?action=view&current=20120930_154907.mp4

You can hear the rhythmic high-pitched tapping in the video. The driveshaft from lower to upper unit doesn't appear to be severed, as the water pump is working like normal. I was not able to pinpoint exactly where the sound was coming from, but it sure sounded like the lower unit, and not the upper. The sound did not change with small adjustments in trim, so the u-joints appear fine, at least on the trailer with no load on the prop.

I will be pulling the drive, but I thought this would be a little update. I still suspect the clutch dog is wiped, which has almost 800hrs of time on it. I will most likely just buy a new lower from SEI unless I find something truly telling after pulling the drive apart. Anyone else have any input?