sealant or gasket when mounting to transom?

[anthonybradley]

Hi,

Rebuilding an old speedboat (gutted back to bare hull) and about to reinstall the Mercruiser (Pre Alpha) gimbal housing and inner transom mount.

Whats the normal accepted method of sealing between the transom and the gimbal housing? Just use a sealent like Sikaflex, or is there a special gasket (searched but can find one)?

Thanks,

Anthony

PS just to clarify, not talking about putting the final drive leg back on, but the actual gimbal mount unit on to the bare transom.

 

[Don S]

Re: sealant or gasket when mounting to transom?

What year? The words "Pre Alpha" really doesn't help much since Merc and many different models that were "Pre" Alpha. And some had different types of gaskets/seals

 

[anthonybradley]

Re: sealant or gasket when mounting to transom?

Hi,

I belive it to be a type "1" according to the Clymer manual; the drive serial number is 4531802. The engine serial number dates from mid- late 70s, and so presume outdrive the same as it appears original.

Many thanks,

Anthony

 

[Don S]

Re: sealant or gasket when mounting to transom?

according to the Clymer manual

You aren't using that for anything but knee pads,...... right!
Does your transom shield have a big cork gasket or seal ring around the parimiter of the transom shield?

 

[Coors]

Re: sealant or gasket when mounting to transom?

The Clymer is not even good for knee pads; the spine glue ain't good, and the pages come loose and blow all over your yard.

 

[Don S]

Re: sealant or gasket when mounting to transom?

The Clymer is not even good for knee pads; the spine glue ain't good, and the pages come loose and blow all over your yard.

LOL, sounds like someone used to have a Clymers at one time and has some serious experience on using them.

 

[Coors]

Re: sealant or gasket when mounting to transom?

After buying an old i/o, Took me 3 weeks to find a real oem on ebay; meanwhile...
What a useless, get you in trouble, piece of s, clymer and seloc are
New boaters; BEWARE.

 

[anthonybradley]

Re: sealant or gasket when mounting to transom?

Does your transom shield have a big cork gasket or seal ring around the parimiter of the transom shield?

Its the 'transom shield' I am talking about reinstalling (I think there are some terminology differences across the pond :redface: ); and its whether it should have a cork or rubber gasket, or just use a good sealant, between it and the transom; thats my question.

I thought the pages fell out my Clymer just because it was old and cheap, didnt realise it was a design feature; hmmm knee pad, thats a good idea.....

 

[Bondo]

Re: sealant or gasket when mounting to transom?

and its whether it should have a cork or rubber gasket, or just use a good sealant, between it and the transom; thats my question.

Ayuh,.....

You should have Either a Cork Gasket, Or the Rubber O-ring......

If your Transom Assembley has a Groove around the parameter,... It needs the O-ring....
If the sealing surface is Flat,..... It needs the Cork Gasket......

None of them are installed with Just Chaulking......

As noted a few days ago,.....
I Don't have a Crystal Ball,+ Don's is Broken, awaiting NLA Parts.....

Got a Picture,..??..??......

 

[Don S]

Re: sealant or gasket when mounting to transom?

In this picture the gasket is item #44. I use a small bead of NON adhesive marine polysulfide sealer (Not Silicone) on both sides of the gasket.

Many of the older drives like that also used a rubber oring type seal that gets glued into a groove in the transom sheild. When you took it apart, it would appear flat and like hard rubber. That is because it's old and used up, scrape it out and put a new round one in. It gets glued into the transom shield with rubber cement (I use bellows adhesive since it's usually handy. This kind takes no sealant on the ring or transom of the boat, when you use a new seal ring.

 

[anthonybradley]

marine polysulfide ??

marine polysulfide ??

Hi,

Thanks for the info so far, think I have got the gasket bit sorted now.

With regards to polysulfide sealant, do they vary much? I see 3M 101 seems to be the popular sealant in the US, but its not generaly available here in UK. Here Sikaflex 291 is commonly used, but its polyurethane rather than polysulfide, and tends to adhere a bit to well for somthing you may want to remove in future.

Does 'marine' polysulfide differ from regular polysulfide? I have used a builders polysulfide sealant above the waterline before now, just wondering if there is anything special about the marine version ?


Thanks Anthony

 

[fishrdan]

Re: sealant or gasket when mounting to transom?

I use a small bead of NON adhesive marine polysulfide sealer (Not Silicone) on both sides of the gasket.

Sorry for digging up this old post, but it I'm not clear on something.

Is this the sealer you are talking about?

http://www.iboats.com/mall/image/vendor/7/big/76-1052.jpg

Black 2 oz. Tube
Part # 1055
# The Industry"?s Number 1 Sealant
# Liquid LifeCulk is the only liquid type sealant that does not shrink when cured.
# It flows into the smallest cracks and seams and stays.
# Cures to a firm bond with the same lifetime adhesion as regular LifeCulk.
# The seal is durable, flexible and stops seepage for good.
# Made from Thiokol LP Polysulfide Polymer.

The "NON adhesive" part threw me. Couldn't I use 3M 5200 or 4200 on the cork gasket,,, or would this make gimble housing removal near impossible in the future? I want to make sure this puppy is sealed up as I found an old dried up, crushed and leaky foam gasket + corroded bolts when I removed the transom assembly.

I'd rather use 5200 or 4200 that I all ready have, but will use the BoatLife if needed.

Thanks!
Dan

 

[Bondo]

Re: sealant or gasket when mounting to transom?

Ayuh,...

4200 will work,... 5200 is more Permanent...

 

[Fishermark]

Re: sealant or gasket when mounting to transom?

Even with the cork gaskets, there are at least two different "sizes" - you would need to measure which you need:

 

[fishrdan]

Re: sealant or gasket when mounting to transom?

AH HA!

I was wondering what the difference was between those 2 gaskets. Thanks for posting that info, I almost ordered the wrong one

*EDIT*

I looked at the gimble housing and from the bottom to the center of the lower bolt hole if 1 1/4", from the lowest part of the gimble housing (drop down in the center) to the center of the bolt is 1 3/8",,, it looks like the gasket for 1 1/2" would fit better

Look at how the original foam gasket sucked up on the bottom

What do you think,,, 65373 gasket or 70974? Is the only difference between the 2 gaskets the bottom section, all bolt holes in the same location?

 

[Fishermark]

Re: sealant or gasket when mounting to transom?

Looks to me like the #5373 would fit better - if you look at the material between the bottom bolt holes it would appear that you want the one with the bigger cut out.

 

[fishrdan]

Re: sealant or gasket when mounting to transom?

Yeah, that's what's throwing me off. The 65373 gasket looks like a better fit, even though SeaSwirl originally used the 70974... My 72 gimble ring has the trim limit switch on top as mentioned in the description of the 65373 gasket, so I think I'm going to order that one,,, hope it's right

Here's some more transom gasket info for the pre-Alphe drives,,, in case someone finds this thread in the future:

27-70794 , Transom Gasket Fits I IA/IB/IC & EZ Shift 120/140 & 160/165 drives (1963-1973)

27-65373 , Transom Gasket Fits MC-I drives having trim limit switch mounted on top of gimbal ring (1977 & older)

 

[fishrdan]

Re: sealant or gasket when mounting to transom?

The 27-65373 gasket fits perfect on my 72 Mercruiser "Pre Alpha" gimble housing.

Just wanted to update the thread in case anyone needs the info in the future.