GEN II Lower Unit Bolt/Stud ?

[tahoejag]

2006 Gen II lower unit. Is that supposed to be a bolt or stud and nut that is directly in front of the speedo tube? When I did my impeller it was a bolt. It was very hard to thread out from start to finish as well as re-assemble, which to me was not right at all. This was the first time I've had the lower and upper separated. Since, I've seen pics and videos and it appears that there is a stud and nut for the lower and not a bolt. Did merc make them both ways or could a service shop had it off and/or tampered with the drive. I did have issues with the dealer recently after purchase, but nothing to do with the drive.

 

[achris]

Re: GEN II Lower Unit Bolt/Stud ?

Yep, just checked my 2006, it's a bolt. And it's definitely from the factory.... as I'm the only one who touches my gear, and I haven't replaced it..

 

[Don S]

Re: GEN II Lower Unit Bolt/Stud ?

Always been a stud and nut.
Below is the parts look up page from the Merc dealer program. Items 4 and 10

 

[tahoejag]

Re: GEN II Lower Unit Bolt/Stud ?

That what I thought what Don S posted....I've seen it as a stud and nut from parts/manuals. Mine is a bolt. It seemed like it was stripped in from the factory. We're talkin I had to reef on this thing to get it out AND back in. Next time I just may carefully have to run a tap down the threads. Or just may look into getting the stud and nut parts as listed....after all it will be serviced from time to time and don't want to risk stripped threads or a busted bolt.

 

[MarkSee]

Re: GEN II Lower Unit Bolt/Stud ?

My 2005 I separated the halves 3 times and it was absolutely a bolt in my case; the only nuts were the ones on the sides.
I was not the original owner so maybe the shop the PO used changed it for some reason.

Mark

 

[Pete104]

Re: GEN II Lower Unit Bolt/Stud ?

Gen II has ALWAYS been a bolt! There are no studs, anywhere on a Gen II gearcase.

 

[ktbarrentine]

Re: GEN II Lower Unit Bolt/Stud ?

So Don's picture is not accurate as far as the stud - nut combination is shown? and what's with that impeller? Thought the vanes curved the other way. I'm sooo confused!

 

[Don S]

Re: GEN II Lower Unit Bolt/Stud ?

Gen II has ALWAYS been a bolt! There are no studs, anywhere on a Gen II gearcase.

?????? Merc might disagree with you.

 

[MarkSee]

Re: GEN II Lower Unit Bolt/Stud ?

The picture Don has is the same as what is showing on the Perf Pro Tech site so.........the conspiracy continues......

http://www.perfprotech.com/store/assembly/GEAR-HOUSING(DRIVESHAFT)(STANDARD-ROTATION),2686-140.aspx

Mark

 

[Don S]

Re: GEN II Lower Unit Bolt/Stud ?

Being a marine tech for many years, I have never seen a Gen II with a bolt, always the stud. I have pulled the stud out with the nut a few times, but I did put it back the way it was and not just throw a bolt in it.

 

[Pete104]

Re: GEN II Lower Unit Bolt/Stud ?

I shouldn't have put it the way I did.
I've been around awhile also Don. I can't possibly recall every Gen II pump I've replaced but there have been plenty that have had a "bolt" at the front of the drive. 1/2" hex bolt with 7/16-14 threads.

 

[achris]

Re: GEN II Lower Unit Bolt/Stud ?

OK.. Here we go..

I have another Gen II here, a 1995, and it has a ...... nut and stud. I also know this one has not been changed since factory, as I am the only one to have worked on it since I installed it new. So it looks like Merc have changed it some time between 1995 and 2006...

Chris.....

EDIT: "Mystery" solved... Have a look at THIS PARTS BREAKDOWN, item #4. In the part number listing it lists two item 4s. One is a stud, the other a 'screw' (bolt).... So, you might have either....

 

[Fun Times]

Re: GEN II Lower Unit Bolt/Stud ?

It shows the stud, but reads either or.
ALPHA ONE (GEN.II) 1998 AND UP
0L100040 & Up
Item #4 16-57984 ----STUD, (.437-14/.437-20 x 2.380) $12.88 $12.56 1
Item #4 10-806327 ----SCREW, (.437-14 x 1.750) $4.48 $4.37 1
http://www.mercruiserparts.com/Show...c=GEAR+HOUSING(DRIVESHAFT)(STANDARD+ROTATION)

I believe the change was in 04.
ALPHA CHANGES, 0W535000 and above
Only cosmetic changes are occurring on the Alpha, which include a redesigned decal.

 

[achris]

Re: GEN II Lower Unit Bolt/Stud ?

...Only cosmetic changes are occurring on the Alpha, which include a redesigned decal.

Mine has that...

 

[oldjeep]

Re: GEN II Lower Unit Bolt/Stud ?

Mine is a bolt and I'm the original owner

 

[Don S]

Re: GEN II Lower Unit Bolt/Stud ?

I guess Merc just uses what ever they have on hand at the time.
I haven't seen one with a bolt, but then again I haven't seen every drive either. I did check the OEM Merc parts site and the picture showed only the stud, but the text stated the bolt as well. No mention of the bolt in my 2009 dealer parts program I have on my computer. I also looked in the service manuals, no mention, even the new 2012 version of manual 14 makes no mention of the bolt.

So to the Original Poster, both bolt and stud have been used. Clean the threads and use some gasket sealer, or grease on the bolt and threads going into the aluminum and it should be easier to remove next time.

 

[tahoejag]

Re: GEN II Lower Unit Bolt/Stud ?

A thanks to all! After reading all the posts...I agree with whatever was on hand at the time if it fit, merc used it. Sounds like a car company I know.....LOL!

 

[MarkSee]

Re: GEN II Lower Unit Bolt/Stud ?

.....whatever was on hand at the time if it fit, merc used it....

Happened all the time in the old days with IBM mainframes; the onsite IBM guys called this "a loosely documented EC (engineering change)".....

Mark