mercruiser transom assembly questions

[woodrat]

So I hope you guys can bear with me here, but I can see that I am going to have a lot of questions by the time I finish replacing my outdrive. I'm a pretty good mechanic and I know I will get it figured out, but this outdrive is a Rube Goldberg device if I've ever seen one! I started taking all the broken stufff off tonight; hopefully I will get it all apart tomorrow so I can take the remains with me when I look at a new gimbal ring and housing on Wednesday.

Questions on replacing my outdirve that I ran into a rock or something at 16 knots:

Can I replace the inner transom plate without pulling the engine? Can I use ordinary marine grade white caulk to seal the gimbal housing to the transom?
Can I replace the engine coupler (if I need to) without pulling the engine?
How can I tell if I need a new coupler?
When I look in my orange mercruiser service manuals, it looks like they are calling my outdrive "mercruiser I". Is that right? I have a 72 120 hp setup.
What else should I be replacing as preventative maintenence as long as I've got things torn apart? I assuming all new bellows and water impeller in the lower unit.

Thanks in advance!

 

[ziggy]

Re: mercruiser transom assembly questions

i don't know the answer to all yer questions.
but i would suspect that you can not replace the transom plate w/o pullin the engine. probably have to pull the engine to do the coupler too. as for how ya can tell if the coupler is spent. look at the splines on the inside of the coupler. they would need to be nice and distinct. look for signs of wear on the side of the slines. look at the drive shaft that ya stick into the coupler. if it has wear i'd think the coupler does too.
a 72 could be a model 1 drive. my 72 in my boat is. i think over on boatfix they have a excerpt on determinin the kind of drive ya have. yer orange merc bible would also tell ya.
don't know about the sealing gimble houseing to transom. i'd find out what the proper stuff is before sealin it though. ya probably don't want to do that twice.

as for pm, perhaps ya might consider havein the drive resealed and inspected for wear. my 72 has a worn drive shaft in the lower that needed to be replaced. it got a speedi sleeve instead. good thing i didn't waste my bread. my boat is in need of stringers and ft motor mount board now.
bummer ya hit something at 16Knots...... a boaters worst nightmare come true.......
make sure yer boat is worthy of botherin to fix anything. mine wasn't... ie floors, stringers, transom in good condition.....ya gotta have something to mount all them new parts onto.....
good luck......

 

[woodrat]

Re: mercruiser transom assembly questions

I haven't gotten down to where I can see the coupler yet, but the shaft that came out of there looks fine, so maybe I lucked out on that. Boat is in good shape, solid transom, floor, etc, so I will be fixing it.

I'm hoping to leave the inner transom plate in place and just replace the outer part that is broken. The inner stuff all looks fine.

 

[Reel Poor]

Re: mercruiser transom assembly questions

Can I replace the inner transom plate without pulling the engine?

No..........You cant change the gimble housing without pulling the engine either.

Can I use ordinary marine grade white caulk to seal the gimbal housing to the transom?

I would recommend 3M 4200 not 5200

Can I replace the engine coupler (if I need to) without pulling the engine?

No.......But the motor will be out anyway

How can I tell if I need a new coupler?

If the rubber is all cracked up, or the splines are worn it should be replaced. If the coupler is original , I would recommend relpaceing it.

When I look in my orange mercruiser service manuals, it looks like they are calling my outdrive "mercruiser I". Is that right? I have a 72 120 hp setup.

Thats what should be there.

What else should I be replacing as preventative maintenence as long as I've got things torn apart?

All bellows, water inlet hose, lower shift cable, raw water pump assembly, gimble bearing and grease seal, have the drive pressure tested, service drive lube, check the u-joints, check the upper shifter shaft and bushings for wear, hinge pins and pivot pins for wear, and make sure all grease zirks will take grease.

There may also be things inside the boat that may need serviced or replaced while the engine is out.

 

[woodrat]

Re: mercruiser transom assembly questions

Yes, I figured out yesterday after several hours of trying, that the engine needs to come out. Heck, I've almost got everything undone for taking the engine out anyway by now...

The splines on the coupler and the shaft look nice and sharp and unworn; I don't know if it is the original or not.

My original idea was to get this baby back together this week, so I could keep fishing, but yesterday I realized that that plan is a bunch of hooey. As long as the engine is coming out, I might as well clean it up really nice, and remount the bilge pump in a better place, (and get a much BIGGER bilge pump!) and put the dual batteries in, etc etc. I may even rob the trim tabs off my other boat, that doesn't really need them, and install them on this one.

Going to pick up a new gimbal assembly today, but I'm still looking for a new lower unit. The upper unit looks fine and undamaged, but the lower is trashed.

So, fishing is over for a while... :-(

It has made me realize that I need to get my little aluminum boat back together so I have a standby when something like this happens.

 

[Haut Medoc]

Re: mercruiser transom assembly questions

FYI, there is an assy that just came on ebay for $250. "Buy it now", that looked pretty clean....
If the one you are picking out doesn't work out.....JK

 

[woodrat]

Re: mercruiser transom assembly questions

Thanks, I hadn't seen that one. The one I am going to check out today is supposedly tight, fresh water only and only $175. I'm hoping it is as described. I had one of the local boat salvage guys down here quote me $375 for a used transom assy, and $775 for each half of the drive. Ouch! And this is all used stuff, with no specific guarantee! I guess I should have just parted out my boat as soon as I bought it and pocketed the profit!

I ordered a bellows and gasket kit off of eBay this AM, and made an appointment with the local aluminum welder tomorrow to finish fixing my skiff so I can get back on the water.