OMC Transom (Big Rubber Circle) Seal.. How Long Do They Last?

Hey guys,

I need some good advice from boat owners who know alot about these older OMC style Transom seals.

My scenario is that I'm looking at possibly purchasing a boat that has this type of transom seal. Now the owner claims the seal was replaced 3 years ago. Told me boat is nice n dry and has been in the water once since replacing because he was in the process of re-doing the interior and never finished. He said the boat has been stored in his shed for the last 3 years.

I asked him once on the water in the last 3 years and he told me that he is an auto mechanic, has alot of projects going, including couple other boats, and never finished the interior on this boat so the boat & new transom seal has been in the shed (non-heated) up in Minnesota winters.

How long do these seals last?

Do they tear easily?

Does the cold & hot seasons shorten the life of this seal (rubber) I believe it is?

My fear is I'll be in 50ft of water and the boat sinks because this seals leaks due to tearing, wear, age, or puncture wound... Please help me over come my fear with this boat because it's a nice older boat with an OMC 350 5.7L in the boat.

Re: OMC Transom (Big Rubber Circle) Seal.. How Long Do They Last?

The seals are pretty robust. And they are about $100 each (give or take depending on whose you buy). I've got a '72 OMC Stringer with the big 'ol transom hole. I've only had the boat a couple of years, but the boot is holding nicely. I have heard that the OEM boots can last 20 years. I've also heard the other manufacturers out there making replacements are not worth purchasing. If you had a catastrophic failure of the boot on the water, your bilge pump probably couldn't beat it out - however if you've got room, go to WOT and the water should go out the back. Best bet would be to beach it probably.

That said, of all of the things I've heard against the Stringer outdrives, failure of the transom boot is the least common. If you're concerned ... replace it. It's pretty easy.

If you haven't bought the boat yet, I will suggest some caution and research. As an owner of a vintage OMC Stringer ... it'll make a mechanic out of you. Don't get me wrong, I like my boat and I have found several things I like about the Stringer drives. But it's a museum piece and takes more effort than a Merc or Volvo would.

Re: OMC Transom (Big Rubber Circle) Seal.. How Long Do They Last?

southkogs said:

The seals are pretty robust. And they are about $100 each (give or take depending on whose you buy). I've got a '72 OMC Stringer with the big 'ol transom hole. I've only had the boat a couple of years, but the boot is holding nicely. I have heard that the OEM boots can last 20 years. I've also heard the other manufacturers out there making replacements are not worth purchasing. If you had a catastrophic failure of the boot on the water, your bilge pump probably couldn't beat it out - however if you've got room, go to WOT and the water should go out the back. Best bet would be to beach it probably.

That said, of all of the things I've heard against the Stringer outdrives, failure of the transom boot is the least common. If you're concerned ... replace it. It's pretty easy.

If you haven't bought the boat yet, I will suggest some caution and research. As an owner of a vintage OMC Stringer ... it'll make a mechanic out of you. Don't get me wrong, I like my boat and I have found several things I like about the Stringer drives. But it's a museum piece and takes more effort than a Merc or Volvo would.

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The boat is a 1980 Crestliner 18ft Bowrider with an OMC 350 5.7 / OMC Outdrive. Was the same seal used in 1980 as the one that is on your boat?

I have heard the OMC outdrive is almost "Bullet Proof" as long as they are maintanced yearly.

What about the OMC engines?

Have you put alot of money into your engine so far?

Some of the repairs you've done so far?

Re: OMC Transom (Big Rubber Circle) Seal.. How Long Do They Last?

jmw129 said:

The boat is a 1980 Crestliner 18ft Bowrider with an OMC 350 5.7 / OMC Outdrive. Was the same seal used in 1980 as the one that is on your boat?

I have heard the OMC outdrive is almost "Bullet Proof" as long as they are maintanced yearly.

What about the OMC engines?

Have you put alot of money into your engine so far?

Some of the repairs you've done so far?

Click to expand...

Ayuh,... From yer other thread 'bout blow-by, We know yer not yer own Mechanic...
Sooo,...
An OMC Stringer drive ain't something You need...

Re: OMC Transom (Big Rubber Circle) Seal.. How Long Do They Last?

most i/o boats are relying on rubber parts below the waterline to keep them floating. On some designs, the rubber is simply more visible than others.
to chime in on the original question. I've seen original boots go 25 years and look great - still supple. I've seen aftermarket ones last only 1 season due to a rubber compound issue some suppliers had.

Re: OMC Transom (Big Rubber Circle) Seal.. How Long Do They Last?

Bond-o said:

Ayuh,... From yer other thread 'bout blow-by, We know yer not yer own Mechanic...
Sooo,...
An OMC Stringer drive ain't something You need...

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Yes you are correct! I have been active on the forums lately & everyone has been very kind to offer helpful advice.

Yes I'm not my own mechanic but I'm also quickly learning that is if you don't want to get hammered in the pocket book by paying for outrageous mechanic lablor & part mark up that you'll be doing some or most of your own work on the boat while constantly improving & self studying to help me save money & have the confidence to just go for it.

I have a mechanic that seems to lean heavily towards mercruiser I /O and dosen't seem to be a fan of OMC unless it's an Evinrude or Johnson.

He told me if the transom seal ever needed to be replaced that it would cost me $1,600? Sound right?

Re: OMC Transom (Big Rubber Circle) Seal.. How Long Do They Last?

Howard Sterndrive said:

most i/o boats are relying on rubber parts below the waterline to keep them floating. On some designs, the rubber is simply more visible than others.
to chime in on the original question. I've seen original boots go 25 years and look great - still supple. I've seen aftermarket ones last only 1 season due to a rubber compound issue some suppliers had.

Click to expand...

That's good to know and also bad on this crestliner if the rubber transom seal that was replaced 3 years ago falls quickly into the "Junk" group.

Re: OMC Transom (Big Rubber Circle) Seal.. How Long Do They Last?

jmw129 said:

He told me if the transom seal ever needed to be replaced that it would cost me $1,600? Sound right?

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$75 to $150 for the part. (aftermarket vs. OEM)
1.5 hours labour to change it.

You do the math...

I'll do it for ya for $800... save half your money!!
I think he's just trying to steer you away from an OMC... wisely

Re: OMC Transom (Big Rubber Circle) Seal.. How Long Do They Last?

I have a mechanic that seems to lean heavily towards mercruiser I /O and dosen't seem to be a fan of OMC unless it's an Evinrude or Johnson.

Click to expand...

Ayuh,... You'll want to line up yer New Mechanic that does work on OMCs before ya buy this boat...
The Mechanics who'll work on 'em, are gettin' as rare as the drives, 'n their parts are...

Re: OMC Transom (Big Rubber Circle) Seal.. How Long Do They Last?

Howard Sterndrive said:

$75 to $150 for the part. (aftermarket vs. OEM)
1.5 hours labour to change it.

You do the math...

I'll do it for ya for $800... save half your money!!
I think he's just trying to steer you away from an OMC... wisely

Click to expand...

Have you changed one of these yourself?

My mechanic told me that the outdrive has to come off in order for the old seal to be removed, new seal attached & sealed, and then the outdrive put back on?

Is that correct or BS?

Re: OMC Transom (Big Rubber Circle) Seal.. How Long Do They Last?

Howard Sterndrive said:

$75 to $150 for the part. (aftermarket vs. OEM)
1.5 hours labour to change it.

You do the math...

I'll do it for ya for $800... save half your money!!
I think he's just trying to steer you away from an OMC... wisely

Click to expand...

You made the comment "Wisely" at the end. Just curious to know what your experience has been with OMC engines & OMC Transom Seals? Or what you know from trusted sources?

Re: OMC Transom (Big Rubber Circle) Seal.. How Long Do They Last?

jmw129 said:

You made the comment "Wisely" at the end. Just curious to know what your experience has been with OMC engines & OMC Transom Seals? Or what you know from trusted sources?

Click to expand...

Ayuh,.... Howard is 1 of our resident OMC Experts here at iboats,....

Re: OMC Transom (Big Rubber Circle) Seal.. How Long Do They Last?

jmw129 said:

Have you changed one of these yourself?

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yes

jmw129 said:

My mechanic told me that the outdrive has to come off in order for the old seal to be removed, new seal attached & sealed, and then the outdrive put back on?
Is that correct or BS?

Click to expand...

both. The manual says to remove outdrive. and that is included in my 1.5 hours. 15 minutes off, 15 minutes back on. 1 hour for the seal which includes mixing some marinetex if the screw holes in the transom are spotty.
However, on a hot sunny day, with a pail of hot soapy water, all that needs to be removed is the propeller, trim tab, and water directors....cuts about 20 minutes off the job.

OMC went out of business for the most part 15 or 20 years ago. That style of drive you are looking at was last made in 1985. Your mechanic doesn't want to work on it because it is old, and stuff breaks easier when it is old. And OMC drive parts are typically 3 to 10 times more expensive than Mercruiser Alpha One parts.

Re: OMC Transom (Big Rubber Circle) Seal.. How Long Do They Last?

Howard Sterndrive said:

yes

both. The manual says to remove outdrive. and that is included in my 1.5 hours. 15 minutes off, 15 minutes back on. 1 hour for the seal which includes mixing some marinetex if the screw holes in the transom are spotty.
However, on a hot sunny day, with a pail of hot soapy water, all that needs to be removed is the propeller, trim tab, and water directors....cuts about 20 minutes off the job.

OMC went out of business for the most part 15 or 20 years ago. That style of drive you are looking at was last made in 1985. Your mechanic doesn't want to work on it because it is old, and stuff breaks easier when it is old. And OMC drive parts are typically 3 to 10 times more expensive than Mercruiser Alpha One parts.

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Howard, thank you for the helpful input. I didn't realize at first that you work on these outdrives or should say have worked on many of these outdrives back in the day when they were once common probably.

Howard, what do you think of these after market seals that are sold here on iboats such as Sierra or Mallory? Do they have the 1-2 year need to be replaced problem?

Re: OMC Transom (Big Rubber Circle) Seal.. How Long Do They Last?

Bond-o said:

Ayuh,.... Howard is 1 of our resident OMC Experts here at iboats,....

Click to expand...

I'm doing two posts here, but the first is to agree with Bond-O and suggest that you listen closely to Howard. He's saved my bacon with his advice a number of times. The "Obi-Wan-Kenobi" of OMC.

Re: OMC Transom (Big Rubber Circle) Seal.. How Long Do They Last?

Big post ... hope it helps

jmw129 said:

The boat is a 1980 Crestliner 18ft Bowrider with an OMC 350 5.7 / OMC Outdrive. Was the same seal used in 1980 as the one that is on your boat?

Click to expand...

I don't think it's the same part number, but it's the same application. 1980 should be a 800 Stringer and mine is an electric shift.

jmw129 said:

I have heard the OMC outdrive is almost "Bullet Proof" as long as they are maintanced yearly.

Click to expand...

That's true of most things. Honestly, I've found my system to be pretty robust - but I got into this deal REAL cheap.

jmw129 said:

What about the OMC engines?

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That is a little past me beyond what I have. When I was looking at the boat I bought, I had a buddy with me who was very familiar with the engine in it (Chevy 250 I6). The motor itself ran exceptionally well, and has been a gem for the couple of years that I've been running it. It's easy to work on and there seem to be plenty of parts for it.

jmw129 said:

Have you put alot of money into your engine so far?

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Had a purchase budget of $2K, and wound up getting this boat for $500. The hull and interior are in incredible shape for the boat's age. Since I've had it, I've probably spent about another $1,000 on parts for the steering, starter, trim motor and reserve outdrive (happened across a good deal). Between all the stuff I've done, and will do this winter, I'll be just hitting my original $2K budget and she'll be a pretty trustworthy boat. If I can keep her going for a few years, I'll be in good shape. I'll probably start looking for something else within the next five years and this one will be the fun antique that I own ... and sometimes works

jmw129 said:

Some of the repairs you've done so far?

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I got the deal I did because the sterndrive locked up on sea trial. That required a little work on the upper gearcase, and became the reason for the reserve outdrive (which is what I've been running on this season). I've also had the tilt motor rebuilt, changed the solenoids, had the starter rebuilt, replaced the steering cable and helm, and done a bunch of general cleaning. This winter, I'll have the trim motor rebuilt, change the thermostat out, change the impeller on the lower unit and do some trailer work.

Latest pics of my boat are here: http://forums.iboats.com/showthread.php?t=507096

I like my boat, and am glad that I got it. It's been fun to play with, and I've even enjoyed the garage time puttsin' around on it. But, like the guys are telling you ... OMC is an abbreviation for "you'll learn to be a marine mechanic in short order."

Re: OMC Transom (Big Rubber Circle) Seal.. How Long Do They Last?

Its correct and takes about 1-2 hours taking your time and thats generous. The price quoted to you is theft.

Re: OMC Transom (Big Rubber Circle) Seal.. How Long Do They Last?

jmw129 said:

Howard, what do you think of these after market seals that are sold here on iboats such as Sierra or Mallory? Do they have the 1-2 year need to be replaced problem?

Click to expand...

I would only use OEM. an extra $40 or $50 for peace of mind that your boat will be floating as you sleep... pretty cheap sleeping pills

most of the aftermarket stuff is fine, but there were some aftermarket boots made that rotted in 1 season. They fixed the issue and warrantied the parts, but were the bad parts 100% purged from every dealer's inventory? who knows.

Re: OMC Transom (Big Rubber Circle) Seal.. How Long Do They Last?

Howard,

When was the issue fixed?

Where do I buy an OEM seal?

That crestliner I like, the seal was replaced 3 years ago and been in the water once. The guy claims it was air tight and the boat ran good. Hasn't been in the water since. The seller claims he was re-doing the interior and never finished it as the boat sat in a protected non-heated Minnesota shed the last 3 years.

Don't know if the guy used an OEM seal but it's worth asking.

Re: OMC Transom (Big Rubber Circle) Seal.. How Long Do They Last?

I don't know the answer but in my boat that I bought 2 yrs old, its now 20 yrs and its the original one.