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Newbee Needs advice

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gonflyn

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Hello, Newbee here with a older (1991) Wellcraft Monaco with twin 5.7lt V8 Alpha One engines and Alpha One Gen two Sterndrives. I bought the boat about 6 months ago, and have had it out about 6 or 8 times on the water. I had to replace a Trim Pump and a Starter Relay. It had been running great, and then...dramatic drum roll.... today, after coming out of the marina and just pushing up the power, got up to about 3200RPM on each engine for about 2 minutes, when the port engine rev'd to about 6000RPM and the boat's forward travel yawed. I brought the power levers back to idle, then tried the port engine in forward with no movement from the boat. Shut it down and single engine back to my marina.

The engine starts and run fine, but not forward or reverse from the Sterndrive. I checked for prop movement with it in gear, and I can turn the prop by hand with the engine off and the shifter in either forward or reverse. So...my question is what did I break? U-joint , gears, shaft? Any ideas?? I figure I'm going to have to tear it apart, just wondering if anyone else has ever had this happen to them?

Thanks in advance for any help!!
 
gonflyn said:
Hello, Newbee here with a older (1991) Wellcraft Monaco with twin 5.7lt V8 Alpha One engines and Alpha One Gen two Sterndrives. I bought the boat about 6 months ago, and have had it out about 6 or 8 times on the water. I had to replace a Trim Pump and a Starter Relay. It had been running great, and then...dramatic drum roll.... today, after coming out of the marina and just pushing up the power, got up to about 3200RPM on each engine for about 2 minutes, when the port engine rev'd to about 6000RPM and the boat's forward travel yawed. I brought the power levers back to idle, then tried the port engine in forward with no movement from the boat. Shut it down and single engine back to my marina.

The engine starts and run fine, but not forward or reverse from the Sterndrive. I checked for prop movement with it in gear, and I can turn the prop by hand with the engine off and the shifter in either forward or reverse. So...my question is what did I break? U-joint , gears, shaft? Any ideas?? I figure I'm going to have to tear it apart, just wondering if anyone else has ever had this happen to them?

Thanks in advance for any help!!
Click to expand...

I'm no expert but had something similar a few years back. Turned out I spun the prop hub. Did it twice actually.... could not get above a fast idle speed without the hub spinning. Cost me about $75 to have it repaired each time (I did not have the proper tools to do it myself). Hope it may be something that easy to repair.....
 
Hi Thanks for the response. I went out the other day and thought about pulling the sterndrive off, but being that my boat is on a mooring on a Airberth, had to rethink the idea of dropping the whole unit or parts into the bay! I did crack it open, to see how difficult it might be to pull it apart. found that there is no gasket between the upper unit and the swivel housing or Gimbal? Just silicone sealant..yeah..not good, when I cracked it, had a little water come out? Guessing that's probably not suppose to be there either! Going to have to wait a few weeks until I have the time to tackle this.
 
Two things

look at very back center of engine and you will see a drive shaft coming from the center of transom into the back of engine. If you can reach this make a white mark on the shaft for visual reference with a piece of chalk if you can if not then just observe closely.

Start engine, does drive shaft spin? If not the coupler is bad and the engine will need to be removed to replace coupler.

If the drive shaft is spinning then either you have a gear (stripped) issue or a propeller hub issue?

As far as all the other issues............once boat is serviced they should find all the crap hidden/disguised by the seller of the boat to you
 
gonflyn said:
Hi Thanks for the response. I went out the other day and thought about pulling the sterndrive off, but being that my boat is on a mooring on a Airberth, had to rethink the idea of dropping the whole unit or parts into the bay! I did crack it open, to see how difficult it might be to pull it apart. found that there is no gasket between the upper unit and the swivel housing or Gimbal? Just silicone sealant..yeah..not good, when I cracked it, had a little water come out? Guessing that's probably not suppose to be there either! Going to have to wait a few weeks until I have the time to tackle this.
Click to expand...

Haul the boat. Drive has to come off anyway to clear the water in the bellows and look for leaks. You can inspect your engine coupler at this time.
 
Thanks for all the info. I can see the "drive shaft" out of the back of the engine spin when the engine is running. I put it back up on my lift, and thought, hey," it's going to be sitting for a while need to flush the engines with fresh water!" hooked up my water, started the engine and waited a minute to have it spit out the exhaust, when the big light bulb above my head went on....duh...the shaft for the water pump isn't spinning! Not familiar enough yet with these drives, but I know that shaft should spin even when the engine/drive is in neutral. So.....what could that tell me??
 
So, I finally got some time to pull the sterndrive off. Due to the fact is on an Airberth, and I don't have a place to take it to hull out, I puller the sterndrive in pieces, first took off the prop, then the lower unit, then upper unit. The only thing I see so far is the oil seal at the top of the drive shaft in the upper unit looks trashed? I can put the lower unit in gear either forward or reverse, and now when I turn the prop shaft, it does turn the drive shaft up through the water pump? It all feels ok, without tearing it apart? So I guess next, I'll look at the upper unit. the spline into the coupler looks fine as well as the U-Joints, so I'm thinking it might be a gear problem in the upper unit aft of the U-Joint? Does anyone have a good way to test or check any of this with it out of the boat?
 
Remove the top cap and look..............4 3/8" 12 point screws. so you will need a 12 point socket, 3/8" size
 
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gonflyn said:
I can see the "drive shaft" out of the back of the engine spin when the engine is running.
That part is technically refered to as a splined "propeller shaft". It is driven by the engine's drive coupler. It powers the two upper unit gears, which in turn rotates the vertical shaft, which in turn operates the "seawater pump".


I put it back up on my lift, and thought, hey," it's going to be sitting for a while need to flush the engines with fresh water!" hooked up my water, started the engine and waited a minute to have it spit out the exhaust, when the big light bulb above my head went on....duh...the shaft for the water pump isn't spinning! Not familiar enough yet with these drives, but I know that shaft should spin even when the engine/drive is in neutral.
That is correct!

So.....what could that tell me??
..... Drive coupler female spline failure..... even if the shaft appears to rotate sporadically or intermittently.
..... Upper unit gear failure.
Click to expand...
 
I would have thought all that oil would make a mess but .....................
The only thing I see so far is the oil seal at the top of the drive shaft in the upper unit looks trashed?
On a GEN II you cant see the seal ? If the oil was not at its correct level or was low this is what happened.
44593f1f.jpg
 
Gears Gone Bad! New movie staring an old set of upper gears the look like Meth Addicts....no teeth left!! Well, pretty sure I found what failed. My biggest question is why? It looks like there has not been a whole lot of oil in the upper unit? I know you're supposed to service it from the bottom until oil runs out of the top from the fill hole once you remove the small screwed in plug. I can see the oil passageway from the lower unit to the upper unit and it looks like it comes in around the Drive shaft where it meets these gears. I had the water pumps replaced when I bought the boat, hence it should have been serviced correctly then. Might have put 15 maybe a max of 20 hours on it since then? How often should the outdrive gear oil be changed, checked or added?
 
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