alpha 1 gen 2 not holding pressure

[Jcris]

If I do this can all the shims be re-used? It looks like I will need to buy 2 special tools, the bearing carrier retainer wrench and spanner.. Are those all I'll need?
I'm going to read this over in the manual and get back with you guys

 

[achris]

Being careful when you disassemble and not losing shims. And the only special tools required are the retainer spanner and an inch-pound torque indicator. You will also need a torque wrench, and some drivers for the seals.

 

[boatguya1]

26-88397A1 looks good on my parts catalog.

 

[Jcris]

Thanks guy's,
I do not have an inch pound torque indicator but I do have a torque wrench that measures in inch pounds. I assume the indicator is more accurate? Is the indicator necessary?To me a good torque wrench is one that is consistently accurate. That usually means expensive. Can a decent indicator be had for $100? I'm also going to take the drive shaft housing to a shop and have them give me an estimate. I'm going to order the spanner and repair kit today. The spanner I can get for $25 and the kit will be much cheaper online. If I buy an indicator what range would I need?
Jcris
also, my torque wrench range is 25--250 lbs/in

 

[Jcris]

[No message]

 

[achris]

No good. You'll be measuring a torque of 6 to 8in-lb... Have a look at my video on setting the rolling torque on the drive gears.

 

[Jcris]

I decided to pressure check the drive again. I put 15 psi on it and could detect no leaks. So I turned the drive shaft by hand and still no leaks. Toggled the shift shaft to try reverse direction and still no leaks. Then I reached into the exhaust cavity and lightly pushed on the drive shaft. Instant leak! With the drive separated I can't get any discernible movement out of the gear that mates with the top of the drive shaft. So those seals are bad? I can't feel any issue with the seal and it doesn't seem worn. There are some wear marks on the shaft where those seals ride but only "polished" marks. Nothing that I can feel. I got an estimate of 2 hours labor to reseal that drive ($170 plus parts) Considering the cost of the tools I need that might be money well spent. What do you guys think?
Could I have damaged those seals when I put the halves together?

 

[Jcris]

For $170 in labor I've decided to let the local Mercruiser mechanic handle it. That seems reasonable to me and I won't have to buy the spanner or the inch pound indicator. Hopefully I'll get it back this week.
Jcris

 

[kenny nunez]

Well you gave it your best shot. You have made the right choice. These drives are very hard to work on without the holding fixtures and without them it is easy to do even more damage.

 

[achris]

...
Could I have damaged those seals when I put the halves together?

No. The leak is not due to anything you did.

 

[achris]

Well you gave it your best shot. You have made the right choice. These drives are very hard to work on without the holding fixtures and without them it is easy to do even more damage.

??? What 'holding fixtures'? I work on them all the time. I have a vice and a bench, nothing more. The only special tools I have are the retainer spanners, an inch-pound torque indicator and the shim tools. Everything else is standard hand tools and the factory service manual. If you take your time, follow the book and apply a modicum of common sense it's not difficult and you won't 'do more damage'.

 

[kenny nunez]

I had a complete shop with the correct drive forks and upper housing mounts from Bob Kerr .

 

[Jcris]

Guy's,
Got the drive shaft housing back from the mechanic yesterday , put them back together and pressured them up. Held 15 psi no problem, life is good. Or so I thought! As I spun the driveshaft I could feel how tight the bearings were, in comparison to before this reseal was done. The bearings feel very rough. There is no way I'd put this drive back on the water. Something is not right . Could it be the pre-load was not set right or checked on these bearings on reassembly. Is that necessary? This drive shaft spun very smooth before the work. Is this the kind of thing that happens when you take apart a 21 year old housing? I've yet to talk with the mechanic so I don't know what his take on this is. Can this be fixed by pulling it apart and adjusting the pre-load? Is this a likely scenario given the age of the bearings and maybe this being the only time this work has been done? I have not put any oil in the drive yet, I doubt that would make any difference. Opinions please.
Jcris

 

[achris]

Guy's,
Got the drive shaft housing back from the mechanic yesterday , put them back together and pressured them up. Held 15 psi no problem, life is good.

Sounds good so far.

Or so I thought! As I spun the driveshaft I could feel how tight the bearings were, in comparison to before this reseal was done. The bearings feel very rough. There is no way I'd put this drive back on the water. Something is not right . Could it be the pre-load was not set right or checked on these bearings on reassembly. Is that necessary?

In order to replace the front seal, the bearing pack needs to come off the yoke. When it's put back on, the pre-load MUST be set, with all the right tools. Anyone who just 'does the nut up' is asking for a very short-lived gear set.

This drive shaft spun very smooth before the work. Is this the kind of thing that happens when you take apart a 21 year old housing?

About 4 months ago I did exactly the job you had done, on a drive of about the same age. When I took the bearings off the yoke they didn't feel right, so I washed them and rechecked. The bearings were unserviceable, too much 'roughness' for my taste, so I replaced them. It's very likely you have the same scenario, given the similar ages.

I've yet to talk with the mechanic so I don't know what his take on this is. Can this be fixed by pulling it apart and adjusting the pre-load?

At the very least the bearings need to be disassembled, cleaned and inspected, closely. If they 'look' ok, then put the inners with the outers and see how they feel. ANY roughness, toss them. Get new bearings from a local bearing shop, not Merc. Shimming will not change if the same brand bearings are used (tolerance on bearing manufacture is better than 1/10th thou). Just set the preload and you should be good. Don't forget to check the bearing in the top housing.Almost a guarrantee that one will need changing.

Is this a likely scenario given the age of the bearings and maybe this being the only time this work has been done? I have not put any oil in the drive yet, I doubt that would make any difference. Opinions please.
Jcris

Hope this helps.

 

[Jcris]

Yes this is very helpful Chris,
I need to talk with the mechanic tomorrow. Very disappointed at this point
Jcris

 

[Jcris]

I talked to the mechanic today and the news is good. He checked it by spinning the drive shaft by hand and was convinced that what I was feeling was the gears meshing without oil. He also said I should vacuum test this drive as well as pressure test it. I read somewhere that vacuum testing on these drives is not recommended. Best not to check vacuum?
I should have this back together this afternoon and if all goes well a driveway test on muffs. What kind of temps would be considered normal in that area?

 

[achris]

..... I read somewhere that vacuum testing on these drives is not recommended. Best not to check vacuum?

Bollocks! When you UNDERSTAND how things work you can make the right 'judgement' call. Forget what 'other people' think (becuase most of the time they don't!), and apply logic to the problem. In this case ask why there are 2 seals ('back to back') on the rotating shafts that have water on one side and oil on the other. Then apply your knowledge of lip seals.

So, let's science the s..t out of this.... Lip seals best seal in one direction, and the higher the pressure the better they seal (without applying ridiculous pressures!). So, one seal faces the oil, and is oriented so that the oil can't get out, but if it was the only seal, the water could be sucked in past it. Like when you run the drive, the oil and gears heat up and you shut it all down. As the oil cools the pressure becomes slightly negative with respect to the surrounding water, and Bob's your aunt and in goes a little slurp of water. Do that enough times and you get a belly full of water and it's goodnight gears. A drive pressure test is very good for picking a leaking OIL seal. But what about the other seals? The ones facing the water. With those in place you eliminate that little slurp of water... So how do we test them? We put a negative pressure (a vacuum) on the inside of the drive. The oil seals open up enough to try and pull air into the drive (to reduce that vacuum) and the water seals now 'lock up', or should. If you see a lose of vacuum, means a water seal is leaking. The only 'qualifiers' on a vacuum test are the shift shaft seal, (only one as it's not a dynamic shaft) and the input yoke, and although it's dynamic but being inside the bellows, it does not have water on the other side (or at least shouldn't ) So you start pulling a vacuum and if the shift shaft seal is a few years old, it may start to leak at around 6" of Hg. That's normal. The drive should never see that sort of 'negative pressure' anyway.

I should have this back together this afternoon and if all goes well a driveway test on muffs. What kind of temps would be considered normal in that area?

If you have good water flow to the drive, then the engine shouldn't get any higher than thermostat opening temperature.

Chris.......

 

[Jcris]

I will pull a vacuum (6 inches) on the drive tomorrow and see how it does. The water temp as read on the dash gauge usually runs around 170. I've not inspected the thermostat since I bought the boat. Also, there has been a change to the reseal kit for the drive shaft housing. There used to be 2 seals on the upper portion of the vertical drive shaft. There is now only 1. A double lip seal that eliminates the need for 2 seals back to back. I'm not sure when this change occurred.
Thanks again Chris,
Jcris
What temp thermostat should I run? 140 or 160?

 

[achris]

Treat the double lip as 2 singles as far as testing goes. Yes, I was aware of that change.

For raw water cooling system, 160?.... And be aware that the gauge temp is just an indication, it's not a 'calibrated' instrument...

Chris..........

 

[Jcris]

I put the drive back together and pressure and vacuum tested it. It passed both tests without issue. My concern at this point remains the tightness of the drive shaft bearings. According to the mechanic the the tightness I'm feeling was from the gears meshing without oil in the drive. He said the tightness would improve a lot after I filled the drive with lube. The tightness remains the same and I'm thinking it's a mistake to run this , even on muffs. These drive shaft bearings were absolutely smooth prior to this work. It seems logical that these bearings would loosen up just a touch when run. But these are the original bearings and again according to the mechanic the races looked good and the bearings were smooth. So why the tightness? This mechanic is very experienced and his reputation is good. He say's it's good to go but also that if I'm concerned he can replace the bearings. He quoted me $160 for just the 2 bearings on the yoke plus labor. He commented that he didn't think the other bearings needed to be done. So what's the smart play here? If I have him replace the yoke bearings, I would also have all the other bearings done. This is very frustrating because I think these drive bearings were in good shape to begin with. When this all started I looked at possibly just replacing this drive with a new one. That drive shaft housing from SEI costs about $900 shipped. If I have this drive repaired (all bearings replaced) that will cost about $400-500 all in. Is this drive worth continued repair? It's an OEM Mercruiser that costs $2500 to replace.Geez!
At this point I have not run the motor but the drive is back on the boat. Do I just run it on muffs and monitor the drive shaft housing temperature? Which I can only do by touch. And I have no frame of reference for how hot/warm it should get at idle or under load. If it seems OK at idle on muffs do I take it to the lake and test it further at higher rpm's? The only way I can afford this boat is if I do most of the maintenance myself.
Jcris