Oil and Water in Drive Shaft Bellows

Hello Everyone,

I've been reading through the Forum trying to find my answers before posting a question that has been dealt with before, but I can't seem to find any posts mentioning my list of problems all together.

OK where to start, the boat is a 1988 Bayliner 1952 with a 3.0L OMC Cobra, its kept on a trailer and thus not left in the water for any great length of time. When moored I noticed water leaking in from the sterndrive, and assumed a problem with the bellows, so pulled the leg with a view to changing it.

Now for the list of problems. When I took the prop off I found fishing line wrapped around the shaft and as I drained the gearbox oil there was water in the lower leg (oil on dipstick was clean and NOT emulsified) so I'm assuming a prop shaft seal has gone? Upon removing the drive there was water and oil inside the UJ Bellows (see attached photo), (there is no rust on the UJ or drive shaft so the water can't have been there long) and in the immortal words of most posters upon inspection the rubber of the bellows seems fine.

So the questions:-
Has water got into the bellows (through poor sealing or a split I haven't found yet) and from there into the boat and the leg, or is it probably two separate faults.

Next if the UJ bellows are fine and correctly sealed, can water get into them from anywhere else?

Lastly any ideas on the oil? I've got a feeling the engine was overfilled with oil when I had the boat, so can engine oil get into the UJ bellows? Engine oil and gearbox oil levels are fine now.

Hope I haven't gone into too much detail but I believe in giving as much info as you can when asking for advice and help!!!

Thank you all


Matt

Welcome aboard first of all. Second you can never give too much info when working on a boat.

Matt1952 said:

1988 Bayliner 1952 with a 3.0L OMC Cobra

So the questions:-

1.... Has water got into the bellows (through poor sealing or a split I haven't found yet) and from there into the boat and the leg, or is it probably two separate faults.

2.... Next if the UJ bellows are fine and correctly sealed, can water get into them from anywhere else?

3.... Lastly any ideas on the oil? I've got a feeling the engine was overfilled with oil when I had the boat, so can engine oil get into the UJ bellows? Engine oil and gearbox oil levels are fine now.

Hope I haven't gone into too much detail but I believe in giving as much info as you can when asking for advice and help!!!

Click to expand...

Matt, you are among the few who provide enough information from the get-go....... kudos to you!


1.... Protocol is to perform a Pressure/Vacuum leak down test on the drive.
Oil must be drained for the pressure test.
Note that a leak-down test involves a time frame.
See the OEM procedure for this.


2.... If the drive has been leaking, oil can exit during the mild pressure build from operation.
When it cools later on, a negative pressure can build within.
If a seal breach allows water to enter, then the cycle repeats itself, therefor it may be possible that the main seal would allow this now water contaminated oil to enter the bellows area.
You'll want to verify this, as I'm not an OMC guy, but the main drive seals are generally single lip seals.

Prop shaft seals are generally installed back-to-back, so if fishing line damaged the AFT-most prop shaft seal, the FWD seal may not hold against a mild interior Negative pressure.
Again, verify this as I'm not an OMC guy.


3.... Short anwer, NO!


Matt, if you have no history of this drive having been re-sealed, now is the time to do this.
Money well worth spending, IMO.

OH.... as for the no rust.... oil that has recently become hydrogentated, does not rust steel as quickly.
So you dodged a bullet, so to speak.

Also note the important OEM drive oil fill procedure.
This is not the same as the Merc drive, for example.
If improperly filled, drive damage will result.

.

Thanks for the welcome, following browsing for the past week or so I'd realised that this was a very friendly forum with a wealth of knowledge, I just hope there's someone who can give me some pointers re the sterndrive. I've done a lot of work on the rest of the boat myself and the engine is this winters project but reading the manual the number of special tools needed is putting me off working on the sterndrive, the problem is I can't find any marine engineers who want to work on a Cobra!!!

Hi Rick, that'll teach me to start responding to someones message, and then stop to answer the phone (I am at work so I suppose the phone should come first ) net result it looks as if I've ignored your response Sorry!!!

Anyway thanks for the good advice, I was reading about pressure testing and may have a go at making my own tester for the experience, the drives fully drained and sitting in the workshop at work. Your point about having it resealed is well taken, as I don't know it's history, I bought the boat two years ago (looking very sorry for itself) and since it worked mechanically most of the time I've been using it while I got the cosmetic work done.

I'm also happy to say I understood most of your answer to part 2, just about, though you're pushing my engineering knowledge to the limit, having said that understanding is one thing actually carrying out the necessary repair work is a different matter, after all I'm just an accountant with a misspent youth , but as I mention above I'm having a hard time finding a good OMC mechanic!!

As for dodging a bullet on the UJ, the more I read the more I realise you're right, and while I'm happy to accept luck whenever it comes my way, I don't depend on it.

Thanks again

Matt

Matt1952 said:

............. the problem is I can't find any marine engineers who want to work on a Cobra!!!

Click to expand...

Yes, very true in many areas.
The OMC company went under in/around 1993 when Volvo Penta purchased the company.
All drives since then, are Volvo Penta cone clutch drives.
Which also means that with a conversion kit, the Volvo Penta SX and DP-S can be retro-fit to the Cobra transom unit.

Just an FYI on that, should you end up having severe and costly Cobra issues.

If you were to upgrade, the ESA and the two shift cables can be completely eliminated.
You'd now have cone clutch engagement, and only one shift cable.

.

That's an interesting thought but I'd better see if the Cobra can be fixed first. I've got to be practical as to costs, its a 1988 boat and has a limited value, when that's reached the accountant in me will say enough's enough.

The boater in me will then go out and buy a newer and bigger boat!!!

Water can get into the bellows with drive oil being pushed past the seal. Eventually you would have seen water and drive oil coming into the bilge via a weep hole in the inner transom bracket. Then the bearing would have to be replaced as well.
So if you are sure the bellow is good you need to pressure test the drive, then vacuum test the drive.
If you find the only seals that went is the propshaft seals then i believe it is a double seal. Pop them out and replace with the 2 seals back to back and your good to go.
Make sure the washers are new on the plugs.

Good call!
This tester is by Tom Green.
Nice guy, and his product is a good one.
You won't be disappointed.

Matt1952 said:

..... I've got to be practical as to costs, its a 1988 boat and has a limited value, when that's reached the accountant in me will say enough's enough.

Click to expand...

Matt, when you've been a boat owner, or boats (plural), for any length of time, you'll soon realize that being somewhat "up-side-down" financially, is
just par for the course.
Lesson #1:
Boats are NOT investments in the normal sense, and are ALWAYS Expenses!
We simply use it up in the form of family enjoyment, much like any other sport, hobby, activity, etc.

DO NOT go into a boat project thinking that you will have a return in terms of Dollars.
It just aint gonna happen............... Well, not often, anyway!


Enjoy the project, but budget yourself for correct and long lasting repairs, upgrades and/or amenities.
If you are upside down to the tune of $x,xxx just check-off $x for each hour of enjoyment. And know that those extra $$$ may have prevented an "on-the-water" failure.

Do not look for a $$$ return..... look for a return in the form of safety first, then fun/enjoyment!
You won't regret it.

Think of the fun this little guy will have.




Nut shelling this.... don't be overly concerned if you end up with (example only) $15K in a $12K boat that runs near perfectly and suits your family needs. Just do it!

Its been a busy day today so sorry for the delay in responding.

Master Mechanic the pressure tester looks great, I'll look into the costs for getting it into the UK, if I can't find one locally. If it turns out to be the prop seals you mention "popping them out" which sounds great, do you not need to dismantle the whole bottom drive or need any obsolete special tools? the manual seems to want me to start taking the whole unit apart to do anything?

Rick, I've owned a couple of boats and while they weren't quite bottomless pits to pour money into, sometimes it felt like it . That said if you asked me I'd have told you every penny was worth it, so no worries on that score, and yes safety first, second and always and even more so now.
I'll post some pictures of the refurb work I've already done and you'll see I don't tend to cut corners, boating's one of my few vices. It's just when I start thinking of a 5-6K engine/drive swap on a boat I paid £2100 for it makes more sense to put that money towards a new boat. (or is this just me trying to justify buying that 27ft cruiser I looked round last week??????

http://www.marineengine.com/parts/o...cturer=OMC+Stern+Drive&section=Lower+Gearcase
#31 in the diagram...... just yank them out with a needle nose pliers. The lips of the seals face outwards.

Just a quick update, took your advice Rick and ordered the pressure tester. If I've got to take it into a marine engineers to get it repaired I at least want to be sure of what is wrong first!!

Can't complain it only took 2 1/2 weeks to get here (standard type post) and at least a week of that was UK Customs clearance and local post.

So once I've tested, probably the weekend now, I'll let you know what I find. If it's prop seals I might even be brave enough to "yank" them out and replace them myself Master Mechanic , and then I'll be back to you for more advice.

Once again thanks for all the help.

Matt

Matt, couple of things..... excuse any redundancy:

Drain the oil before doing the pressure "Leak-Down" test. The vacuum "Leak-Down" test doesn't care!
If you have no history of them being replaced, replace the seals regardless..... and especially since the fish line issue.

Master mechanic said:

http://www.marineengine.com/parts/o...nufacturer=OMC+Stern+Drive§ion=Lower+Gearcase
#31 in the diagram...... just yank them out with a needle nose pliers. The lips of the seals face outwards.

Click to expand...

MM, I don't mean to bust your chops here, but please be careful when making suggestions to these guys.
The lips on the two seals are to oppose one another!
IOW, one seal faces towards the oil side, the other faces towards the water side.
If both are installed as you suggest, the drive will not hold pressure.

Matt, in this image, you can see SEQ #31 (the two seals) and how OMC wants these to be installed.
Pretty much like Merc and Volvo Penta.

Hi Rick,

Thanks for the pointers, the leg is already drained and off the boat.

Just to check when you say

"If you have no history of them being replaced, replace the seals regardless..... and especially since the fish line issue"

do you mean all of the gaskets / seals in the whole leg???? or just the two prop seals. I'm hoping that the pressure test will prove its the prop seals, if it is I'd like to have a go myself.

Thanks about the warning on the directionality of the seals I had noticed that already from MM's drawing, but always better safe than sorry.

Is it really as simple as pulling the old ones out and sliding new ones onto the shaft (right way round of course) the manual offers no real info, and a couple of other threads refer to removing the bearing carrier and special tools?

The only problem I then have is sourcing the seals, OMC parts are hard to come by in the UK, the Sierra Catalogue only seems to list a complete lower leg seal kit!!!

Matt

Matt........

Matt1952 said:

Hi Rick,

Thanks for the pointers, the leg is already drained and off the boat.
FYI..... the lower unit and upper unit must be assembled for the test.

Just to check when you say

"If you have no history of them being replaced, replace the seals regardless..... and especially since the fish line issue"

do you mean all of the gaskets / seals in the whole leg???? or just the two prop seals. I'm hoping that the pressure test will prove its the prop seals, if it is I'd like to have a go myself.
What I mean, is that if the drive has not undergone a complete re-seal since you've owned it, or in the last five years or so......, it's probably time.

Thanks about the warning on the directionality of the seals I had noticed that already from MM's drawing, but always better safe than sorry.
Well again, I don't mean to bust anyone's chops, but this is pretty darn important.
MM's verbiage did not match the schematic, and all too often we tend to follow verbiage.
MM, no offense intended!

Is it really as simple as pulling the old ones out and sliding new ones onto the shaft (right way round of course) the manual offers no real info, and a couple of other threads refer to removing the bearing carrier and special tools?
I'm not an OMC guy, so I can't actually answer this for you.
My guess is that a special tool is required to remove the prop shaft bearing carrier retainer.

Click to expand...

Back to back.

20 bucks for the whole kit for the lower.

You have a pm