Merc 5.7 Mag Alpha One Gen 2 - Drive Issue - Any mechanic guidance pls ?

[s50cam]

Hi

I have a 2005 21ft bowrider with the merc 5.7 350 mag / alpha one drive

Have been using her alot over the last few weeks with no issues. Was out on Saturday and on the return journey travelling at about 25 knots I noticed some intermittent loss of drive, then complete loss. There was a burning smell at the rear and following that if you try to engage forward or reverse nothing happens other than some rattling noise. The engine appears to be fine and fully operational. We got a tow back to port.

I'm not the most experienced when it comes to mechanic's and will have it lifted out tomorrow to get it looked at, just wondered if anyone had an idea what its likely to be and the best fix rather than me being reliant just on the boat yards advice.

Thanks !

 

[julians]

It sounds like the drive coupler has failed,the burning rubber smell and lack of drive being the key symptoms.

A lack of drive on its own could be due to a spun prop hub,but along with the burning rubber smell points to a worn out coupler

See here for more info

http://www.mercstuff.com/spunprop.htm

 

[rafiki_]

Before you lift the boat, lift the leg up and see if you can spin the prop.

 

[s50cam]

Great thanks, I'll check the prop first

 

[paultallett]

Send Mercuryman aka TomParker a message. He's the Mercruiser guru at Tompa Marine. Top bloke and really knows his stuff. service@tompamarine.co.uk

 

[benchmark]

I agree that it sound pretty much as if you have spun your propeller hub, this is a nylon/teflon interchangeable part designed to protect your driv in the event you strike something underwater with the prop. An easy part to change yourself .
Lots of guide videos on the internet.

 

[s50cam]

Hi,

So we pulled the boat out yesterday, my friend has taken it apart this morning to diagnose. When moving her we noticed there was alot of gearbox oil coming out just with the engine running.

He's just sent over the photo's attached and said its the universal joint knuckle which has sheared. Is this now a rebuild or just a new U-Joint Assembly Yoke fitted in ?

There is a local company which rebuilds legs so I'll contact them and tompamarine (Thanks Paul for above) for advice but I did read that the costs of rebuild vs new leg aren't that different if that is the case but there are alot of videos online for replacing the U-Joint on its own ?

Once again any advice appreciated

Cameron

 

[s50cam]

Couple of further photos . . .

My friend is now wondering if we could get the parts and fix it himself

 

[paultallett]

Sorry to see the bad news. Send Tom an email, he'll give you dead straight, honest advice.