Winterized...found 1 sterndrive full of water, instead of oil.

[Oshawapilot]

Helped my BIL winterize their 35' cruiser today, twin 470's.

When draining the starboard sterndrive (Alpha 1's) I found it about 90% full of water instead of oil. Ugh.

No signs of metal in the oil that did come out.

Now, this drive DID have a noise for a good part of this season - a rattle. It got notably worse towards the end of the season, but I had reason to believe it was a failing U-Joint - that was based on the following realities:

1- Everything behaved perfectly normally, the drive shifted perfectly ahead and astern right up until the point it came out of the water.

2- The rattle 100% went away (and everything ran quiet and perfectly smooth) IF you trimmed the drive up slightly...hence why I assumed it was a U-Joint - get everything straight-lined and the U-Joint isn't doing much. If you trimmed the drive up too far, or lowered it all the way down, the noise returned. Turning the wheel too far off centre also caused the noise to return. But put the helm to centre and keep the trim at the sweet spot, and it was perfect - the noise would go away again.

Does that sound like a U-Joint issue, a gimbal bearing issue...both? Or was it the Alpha 1 eating itself?

The boat is out of the water now until probably May of next year, so there's time to address things, but looking for advice. Needless to say the water leak needs to be addressed, but is there an assessment to see if any damage was done, or is it a "if there was no noises coming from the drive itself, put oil back in it and hope for the best" scenario?

Thanks for everyones advice.

 

[Bondo]

Ayuh,..... The only way to answer yer questions is to pull the drive, 'n inspect the u-joints, 'n gimbel bearin',.....

The symptoms suggest yer diagnosis, but a drive fulla 90% water is another problem all it's own,.....

 

[Bt Doctur]

Do not leave the drive empty, fill with a light oil for storage so the internals dont rust

 

[harringtondav]

+1 ^^, plus...

That watery drive could need a full re-seal job. This involves a full tear down which will reveal the condition of the gear sets and bearings and needle bearing shaft surfaces. Check Don S's stickies at the top of this forum for how-to on a pressure test on that drive. This will confirm bad seals, and help ID their location(S).

If you're anxious to see any bad news, pull the top cap from the upper hsg. of the drive. You'll have a good look at the drive shaft bearing race, tapered bearing rollers, and that input gear set. But you have to get to the root of the water entry. Pressure test.

 

[Scott Danforth]

Pull the drive apart and re-seal ASAFP. As in today.

Make sure to find your leak

 

[Oshawapilot]

Thanks all. I'm going to run on the assumption that this is two separate issues at this point, assuming everyone agrees that the rattle is u-joint or gimbal bearing....?

If so, two separate issues:

1/ Gimbal bearing and/or U-joint.
2/ Water intrusion in the drive itself.

As for #2, I have a sneaky suspicion that it may be less expensive to buy a used/refurbished Alpha 1 and just pull and replace it in it's entirety. The drive is in pretty rough shape, a lot of external corrosion, pitting, etc. This time of year (end of the season across most of the country here) I can probably find something for comparable money to what they'll end up spending getting the old crusty one diagnosed and repaired..if it turns out to be repairable at all.

I guess then the big question is...there's multiple gear ratios in these, correct? How do we identify what's in the boat now?

 

[Oshawapilot]

I suspect someones going to say "Get the serial number and we can figure out the ratio that way". Except like I said, the corrosion on this old girl is really, really bad...assuming it's stamped on the drive itself somewhere I question if it's even possible it'll be readable anymore.

 

[Rick Stephens]

If you were full of water I sure wouldn't assume the u-joints were rattling. Water makes a **** poor lubricant for bearings. You need to take a look in there, specially the bottom box where the water would displace the oil.

 

[Oshawapilot]

But would a noise in the drive translate to a very loud rattle in the cabin of the boat itself?

The noise was very evident in the engine bay directly. To the contrary, off the stern even when underway, everything was quiet.

Anyhow, it may be moot, as like I said, it's entirely possible I can find a replacement drive for <$500 which will certainly be cheaper than the labour to tear down, diagnose, and rebuild the existing one. Thankfully Alpha1 Gen1's seem to be reasonably plentiful up here from some cursory searches so far.

 

[achris]

Most likely you have 1.84:1 ratio... That's all the 470 was supplied standard with... But here's the rub... If they are in a bigger boat, it may be that someone changed those drives to 1.98:1 and put a slightly bigger prop on... Pull the top cover off the drive and count the gear teeth....

If you have 17 on the drive gear and 19 on the driven gear (the one on the bottom) it's 1.84. If it's 20 and 24, then it's 1.98:1...

Best thing. Post some data and I can work out, with reasonable confidence, what the ratio is.
I need, engine speed at full throttle, boat speed at full throttle (with a GPS, and preferably in knots) and the propeller pitch in inches (it's stamped into the prop hub)

Chris.......

 

[harringtondav]

Thanks all. I'm going to run on the assumption that this is two separate issues at this point, assuming everyone agrees that the rattle is u-joint or gimbal bearing....?

If so, two separate issues:

1/ Gimbal bearing and/or U-joint.
2/ Water intrusion in the drive itself.

As for #2, I have a sneaky suspicion that it may be less expensive to buy a used/refurbished Alpha 1 and just pull and replace it in it's entirety.

I guess then the big question is...there's multiple gear ratios in these, correct? How do we identify what's in the boat now?

If you or your BIL don't have the tools to tear down and repair the drive as Scott Danforth suggests, I'd go with the lowest cost replace option. Having a shop do the autopsy will be pricey. A rebuild will probably put you over the top compared to a replacement. A refirb or SEI drive comes complete with new U joints. You're on you own with the gimbal bearing.

You can count the gear teeth on the top gear set. This will define your ratio. But you need to let this team know the year of the drive. I think ratios in Alpha I and II are different.

Pull the drive, and remove the lower prop shaft hsg. Remove the top cap of the upper gear hsg where you can see the top gear set. Clean things up enough to get a sharpie mark to stay on a gear tooth on the input pinion and the drive gear. Rotate the splined engine coupler shaft and count the teeth on the input pinion. Then do the same to count the teeth on the vertical drive gear. This will define your gear set. The year/model of the drive will define it's ratio.

 

[achris]

The ratios for the various drives didn't change going from Alpha One to Alpha One Gen II... A 1.94:1 Alpha behind a 3L was still a 1.94:1 with an Alpha One Gen II... The V8 Alpha Ones were 1.5:1, so were the Gen II drives....

Also, the 470 production finished before the Gen IIs came out. So it can only be Alpha One or earlier.

Also, just be a bit careful defining the overall drive ratio by the top housing tooth count alone. A couple of ratios required a different tooth count in the lower box, like the 2:1, which uses the 24/24 top box count, the same as the 1.65:1, but with different gears in the lower housing. And the 2.4:1, which uses the same gears (20/24) in the top box as the 1.98:1...

Chris...

 

[wellcraft-classic210]

Wondering about the condition of yuor main bellows around the u joints -- if that's leaking the ujoints will get soaked and also the water will get pushed into the drive through the upper shaft seals --

 

[harringtondav]

The ratios for the various drives didn't change going from Alpha One to Alpha One Gen II... A 1.94:1 Alpha behind a 3L was still a 1.94:1 with an Alpha One Gen II... The V8 Alpha Ones were 1.5:1, so were the Gen II drives....

Also, the 470 production finished before the Gen IIs came out. So it can only be Alpha One or earlier.

Also, just be a bit careful defining the overall drive ratio by the top housing tooth count alone. A couple of ratios required a different tooth count in the lower box, like the 2:1, which uses the 24/24 top box count, the same as the 1.65:1, but with different gears in the lower housing. And the 2.4:1, which uses the same gears (20/24) in the top box as the 1.98:1...

Chris...

Chris, I knew about this, but I wasn't sure about Oshawapilot 's interest in counting teeth on the FWD gear set. Would the counting coupler shaft revs against prop shaft revs method be the best way? If so, would you be so kind as to explain that method? I'll just embarrass myself if I try.

 

[achris]

Chris, I knew about this, but I wasn't sure about Oshawapilot 's interest in counting teeth on the FWD gear set. Would the counting coupler shaft revs against prop shaft revs method be the best way? If so, would you be so kind as to explain that method? I'll just embarrass myself if I try.

That's the one I suggested for people who can't count teeth...

It's usually done with the drive still on the boat, and you remove the spark plugs, put the drive in forward gear and start turning the engine. Have someone on the outside counting turns of the prop shaft... When they get 10 turns on the prop shaft, you divide the number of turns you needed to make on the engine by 10 and you have the drive overall ratio....

You can do exactly the same with the drive off. Just put the drive in forward gear and start turning the input yoke. Count the turns required to get 10 turns of the propshaft, divide that number by 10 and you have the ratio.....

Chris.......

 

[Oshawapilot]

Thanks all. Went back up to the boat briefly this morning and refilled the drive with lube to at least put it in a safe state of storage and displace the water until it's decided what to do.

Managed to get a mostly readable serial number off the portside engine (the starboard was completely corroded out of existence) - the bad drive in question is actually the starboard, but it's safe to assume that both are the same ratio of course, so hopefully the serial number helps identify the ratio for those who know how to decode that? There's also a large "D" stamped to the right of the serial number and I found some references online indicating that on some A1's this corresponds to the ratio, but in searching afterwards I can't find anything that correlates to a "D" marking and the ratio.

I think it's 8440758?

And the "D" Stamp:

 

[Rick Stephens]

D is 1.84:1

Here's a chart, top chart says u-joint stamp, but they use the same one externally too.

 

[Oshawapilot]

Awesome, I knew I was just missing a piece of the puzzle somewhere.

Ok, we have something to work with now.

I'm putting out some feelers to see if this drive is worth rebuilding or not now vs replacing. Here's why I'm thinking the latter may be wise.

 

[harringtondav]

If you decide to bail, and if you have the energy, spray it down, and repeat with CLR until it looks presentable. Then post it on eBay as is for a few - several hundred $$. Be honest with what you know, "took on water, ran OK". Some salvager or a handy DIY in worse shape may bite and part it out for the housings and whatever else may be salvageable. This could defray the costs of a rebuilt unit or a SEI replacement.

 

[achris]

The serial number is B440758, it's a 1987 1.84:1 drive.

As that ratio is no longer available in a new or aftermarket drive you would have to go with a 1.81:1... The difference at 4000rpm would be 36rpm, enough to make a difference in a twin engine installation.

One option is of course to find a second hand unit with the right (1.84) ratio... The other would be to also replace the lower housing on the port drive (it's the gears in the lower housing that made the difference between 1.81 and 1.84)..

The change was made by Mercury in the 90's because of 'gear noise' complains with the 17:28 gear set (in the lower housing). The change was to a 13:21 gear set... In a single engine set up, it made no difference, but in twins, it created a few problems.

Chris.....