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Alpha 1 breakdown

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Yankee Pride

New member
My Alpha 1, Gen 1 CR outdrive recently broke down while under way. After removing the outdrive and getting it to my shop, I removed the gear lube plug and was showered with oil. How can pressure build up in the gear case?
 
A drive with no oil monitor will naturally pressure up in use due to increased temperature but that should return to normal once it cools down.
Maybe the upper shaft seal has leaked a little exhaust gas into the upper gear housing and that has become trapped? Just a guess.

Rod
 
This is a Mercruiser Alpha 1 Gen 1 counter rotating and is only 6 years old. I had the impeller replaced this spring before going into the water. I put about 2 hours on the drive before the breakdown.
 
If this drive is six years old, is it aftermarket?
Was the drive cold when the gear oil came out under pressure?
Did you remove the lower plug or the upper?
I would take both plugs out and attach the pressure tester to the lower and see if you can pump air out of the upper.
 
This is not an aftermarket out drive. The outdrive was cold when I removed the plug and I did remove the upper plug first only because I was having difficulty getting the bottom plug out. I will do a pressure check on it. Thank you both for your advise.
 
Did you notice any level fluctuations or pressurizing tendency in the drive oil monitor while in use?
Normally newer drives with the monitor bottle do not pressure up; as the drive warms up the fluid simply backs up a little into the monitor bottle.
It sounds as if something is wrong with your oil line connecting the bottle to the drive such that the fluid is not flowing.
Perhaps the anti-dribble valve is blocked, or the line is pinched.

There is no way a drive that new should have failed already. How many hours on it total?
Has there been a recent prop strike that might have caused internal gear damage?
Was the drive properly filled with oil?


Rod

Rod
 
This drive was a replacement (6 years ago) of the original port drive on my boat. The boat is a 1990 and has no oil monitor system on it. The drive was filled to the correct capacity in the spring through normal maintenance I have done every year. When the drive broke down, I was under way and smelled gear lube just before I felt a couple of good thumps coming from the drive. I slipped into neutral at that point and saw a sheen of oil on the water at the stern. I put the drive into gear and heard and felt a couple more good thumps before putting it back into neutral. I made it back to my marina on the starboard drive. there is only about 25 hrs on the drive and no prop strike. I'm thinking your original thought about an exhaust leak may be correct. When I drained the rest of the gear lube out, it had a much stronger smell than usual as could be from over heating.
 
Gotcha now. I missed the fact that it was an original Alpha One.
The bummer about pre-Gen II drives (up to and including 1990) is that if they overpressure for some reason the pressure has no where to go, and eventually a seal will go allowing fluid out, and later water in.
Merc does stock a lube oil monitor kit that can be retro-fitted to any earlier drives. It connects by a fitting into the vent screw hole and provides the same functionality as the newer drive monitors. You may want to consider adding them for the future.
As far as the failed drive is cincerned it seems suspicious to me that it failed that quickly for no apparent reason.
Was it an OEM new drive or rebuilt?
Since you cannot simply bolt a new gen II leg onto an earlier transom assembly, you are going to be stuck with finding a repalcement Alpha One CR drive. Thumps and bangs from a drive usually mean complete gear failure and an expensive service job. Then there is no guarantee how long it will last.
You maybe want to consider trying to find a NOS OEM replacement drive. 1.5 gear ratio, right?

Rod
 
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