Missing transom bolt on Mercruser outdrive to bellhousing.

[dmiles452]

This past weekend my boat started taking on water in the engine bay. When I pulled the boat up out of the water and onto the trailer I noticed that one of the bottom bolts that go thru the transom at the outside mounting bracket was missing. My question is with the engine installed I cannot even see where this bolt comes thru to the engine bay. Is there some trick to getting this bolt back in and tightened properly

 

[alldodge]

You didn't mention which drive but I'll guess it's a R or MR but motor needs to come out, and while your at it check the transom
https://www.mercruiserparts.com/bam/subassembly/30872/2203/40

 

[nola mike]

You didn't mention which drive but I'll guess it's a R or MR but motor needs to come out, and while your at it check the transom
https://www.mercruiserparts.com/bam/subassembly/30872/2203/40

+1, those bolts corrode either because of rotten transom or lead to rotten transom. Guessing that if you try to turn the other one it will just spin.

 

[Bondo]

This past weekend my boat started taking on water in the engine bay. When I pulled the boat up out of the water and onto the trailer I noticed that one of the bottom bolts that go thru the transom at the outside mounting bracket was missing. My question is with the engine installed I cannot even see where this bolt comes thru to the engine bay. Is there some trick to getting this bolt back in and tightened properly

Ayuh,..... The very bottom bolts are the anode bolts which are aluminum, 'n generally speakin', when they corrode in two, the transom is very rotten,.....

Ya gotta pull the drive, then the motor to get at 'em,.....

 

[kenny nunez]

If you are very lucky and the transom is still solid the bolts can be replaced.
This depends on how flexible you are, what engine, the boat‘s design.
Punch out the remains tith a slender punch, clear the hole with a 1/2” drill bit. Depending on what model you have you will need an anode bolt kit with the self locking 1/2” 13 nuts.
Otherwise as AD & Bondo posted the whole power package, Transom assembly have to come out.

 

[nola mike]

I'll note that when I encountered this, I had some localized rot around the holes. I was able to scrape out the rotten areas (maybe 1/2"), fill with epoxy, redrill the holes, and then slather the whole mess in 4200 before reinstalling. I probably could have just used 4200 instead of the epoxy--those are through bolts with low clamping force between the transom shield and gimbal housing. I was able to do it with the transom assembly in place, but motor out.

 

[tank1949]

This past weekend my boat started taking on water in the engine bay. When I pulled the boat up out of the water and onto the trailer I noticed that one of the bottom bolts that go thru the transom at the outside mounting bracket was missing. My question is with the engine installed I cannot even see where this bolt comes thru to the engine bay. Is there some trick to getting this bolt back in and tightened properly

Crappy early MC design to minimize electrolysis (I guess). My 86 Sea Ray had aluminum bottom bolts. When I replaced engines, I went back with SS. Lots of 5200 too.... Luckily, my transom was OK.

 

[dmiles452]

Does anyone know of a "fix" for a missing bolt in the outdrive. It needs to be able to go thru the transom and expand as tightened kind of like a hollow wall fastener but a bit stronger.

 

[dmiles452]

If you are very lucky and the transom is still solid the bolts can be replaced.
This depends on how flexible you are, what engine, the boat‘s design.
Punch out the remains tith a slender punch, clear the hole with a 1/2” drill bit. Depending on what model you have you will need an anode bolt kit with the self locking 1/2” 13 nuts.
Otherwise as AD & Bondo posted the whole power package, Transom assembly have to come out.

The engine is the GM 350, so there isnt a lot of room. I cant even see where the bolt comes thru the transom. I am not even sure I should be able to see it. The motor was rebuilt 3 years ago and has less than 50 hours on it. It was rebuilt before I owned it. I did check with the marina that did the work and it was legit. Why they didnt replace the bolts is unknown to me.

 

[jimmbo]

Which Bolt are you referring to, on what Outdrive? You could look up a Parts Diagram for the Outdrive involved, and get the Part Number

 

[dmiles452]

Which Bolt are you referring to, on what Outdrive? You could look up a Parts Diagram for the Outdrive involved, and get the Part Number

since making this post i did look up the part and maybe I can find it at the local marina

 

[jimmbo]

You might be able to order it online from a couple of places. Marine Engine dot com, is one

 

[JASinIL2006]

Those are a challenge enough with the motor pulled... I can't see any way you could replace it with the motor in place.

 

[tank1949]

The engine is the GM 350, so there isnt a lot of room. I cant even see where the bolt comes thru the transom. I am not even sure I should be able to see it. The motor was rebuilt 3 years ago and has less than 50 hours on it. It was rebuilt before I owned it. I did check with the marina that did the work and it was legit. Why they didnt replace the bolts is unknown to me.

They got their money and figured that you would be a repeat ($$$$$). That particular MC design has sunk a lot of boats.

 

[Bondo]

The engine is the GM 350, so there isnt a lot of room. I cant even see where the bolt comes thru the transom. I am not even sure I should be able to see it. The motor was rebuilt 3 years ago and has less than 50 hours on it. It was rebuilt before I owned it. I did check with the marina that did the work and it was legit. Why they didnt replace the bolts is unknown to me.

Ayuh,.... Because it wasn't broken 3 years ago, 'n is well outside the scope of work they were doing,.....

 

[dmiles452]

They got their money and figured that you would be a repeat ($$$$$). That particular MC design has sunk a lot of boats.

Yep I can understand why. If I had not made a return trip to the marina where the boat was docked it would have been sitting on the bottom by the following weekend.

 

[dmiles452]

Ayuh,.... Because it wasn't broken 3 years ago, 'n is well outside the scope of work they were doing,.....

I see your point, its a money thing. I would never complain about hardware being replaced during a rebuild, especially when the failure results in a sinking boat. The outdrive was rebuilt at the same time.

 

[tank1949]

I see your point, its a money thing. I would never complain about hardware being replaced during a rebuild, especially when the failure results in a sinking boat. The outdrive was rebuilt at the same time.

go back with ss and lots of 5200.

 

[dmiles452]

go back with ss and lots of 5200.

Do you know what size bolt it is and thread pitch? Once thru the transom what does it thread into? The bell housing?

 

[tank1949]

Do you know what size bolt it is and thread pitch? Once thru the transom what does it thread into? The bell housing?

Mine were 7/16 or 1/2". I can't remember. No threads or mine were not there. You probably could use a 1/2" regardless. I used carriage bolts and lock nuts. Hard to find C bolts in ss, but I don't see why a hex-head and fender washer and lots of 5200 wouldn't work. Make sure no rot in bolt hole or you are just prolonging more headaches. You had better be double jointed since accessing the backside w/o pulling motor will be a pain in the butt.