Omc Leg Gasket

[Sugo]

When re-installing an OMC Cobra leg back on the boat should the gasket be installed dry or should it have some Black Permatex on it? I have heard I should not use the same stuff I used on my oil pan and valve cover ? I have also heard it should not have anything on it.

 

[Don S]

Re: Omc Leg Gasket

I have heard, ---- I have also heard

That always scares me. Did this stuff you "Heard" come from a qualified tech, or just some guy on the dock trying to sound like he knows something ? Makes a big difference. It's right up there with "I read" Yeah, right, you can read any thing you want to believe on the internet.

Ok, enough of that.
According to the OEM service manual (#508289 if you want to know which one), it says to install new gasket. Nothing about any sealer of any kind. In the places where they do want sealer, they say so. In the manual and show pictures.

So now you have heard/read, my version.
PS: It's on page 9-3 of that manual if you want to look.

 

[Sugo]

Re: Omc Leg Gasket

Good point about where info comes from, Thanks for your time.

 

[zbnutcase]

Re: Omc Leg Gasket

I coat the gasket with grease, easy to remove next time and might even help prevent corrosion-and Cobras have thin enough sealing surfaces as it is. 'nutcase

 

[Sugo]

Re: Omc Leg Gasket

If the gasket has a small tear would this cause water to mix with the leg oil when running? (In the driveway hooked up to the hose w/Ear Muffs)

 

[Don S]

Re: Omc Leg Gasket

Depends on where the tear is, Put a new gasket on it.

 

[Lou C]

Re: Omc Leg Gasket

The gasket between the drive and the pivot housing needs to be coated on both sides with OMC Gasket Sealer (the equivalent is Permatex Aviation Sealer) before installing it. I've done it this way always and never had a problem getting it off because this stuff never hardens..
see:
http://support.crowleymarine.com/article/17323945/

there are a number of articles here right from the factory service manuals....

 

[Sugo]

Re: Omc Leg Gasket

Once I pulled off the leg I realized that gasket is not my problem. I took off the inspection plate off the top of the leg and it is full to the top with oil/water mix. The leg oil was clean before I took it off to swap the motor so it has only run for 2 min with the oil in this condition. Could this be caused by a fault in the water pump ? Any ideas?

 

[havasuboatman]

Re: Omc Leg Gasket

You are going to have to drain that crap out of that drive and do a pressure and vacuum test to find out where the water is getting in.
Do the test with the water pump housing and impeller removed so that you can see if the water pump drive shaft is leaking.

 

[Sugo]

Re: Omc Leg Gasket

I took the water pump off and it looks like it is the water pump drive shaft that is leaking. It there a trick to remove the circular cast plate behind the water pump so that I can get to the seal behind it ?

 

[havasuboatman]

Re: Omc Leg Gasket

Book says to grab it with a pair of visegrips between the water passages and pull it straight back. From the look of yours, All I can say is wiggle it, work at it and be prepared to need a new one by the time you get it out. The part name is adapter plate.

 

[Sugo]

Re: Omc Leg Gasket

Thanks,
I will give that a try on Monday, If I am going to replace the adapter plate and seals I guess I should replace the two bearings on the shaft as well. Do I need any specialty tools to remove the u joint water pump shaft to replace the bearings?

 

[bruceb58]

Re: Omc Leg Gasket

What makes you think it is the water pump gasket. It may very well be but what made you come up with that conclusion? Did you pressure test the drive?

 

[cr2k]

Re: Omc Leg Gasket

Yes if you start messing with the bearings you will need stuff to ensure that they have the proper spacing and preload.

Unless the bearings are rough or pitted that amount of run on "wet" oil should not hurt them.

 

[Don S]

Re: Omc Leg Gasket

When you took the outdrive off the boat, was the water in the bellows by any chance?

 

[Sugo]

Re: Omc Leg Gasket

The reason I believe it is the seal behind the adapter plate is that there is milky oil seeping on the outside of the adapter plate on the bottom of the water pump drive shaft. There is also traces of milky oil on the water pump impeller. There is no water in the bellows. The reason I asked about the bearings is that I herd a bit of a high pitch ringing in the top of the leg while the new motor was running and something must have caused a seal to become faulty all of a sudden. The gears don't appear to have any chip or abnormal wear.

 

[bruceb58]

Re: Omc Leg Gasket

You need to pressure test your drive. You have no idea that is the only place that you have a leak.

 

[Lou C]

Re: Omc Leg Gasket

For sure you need to do a pressure test...there are a number of other places the water could get in and on mine that water pump shaft seal was replaced but also a seal on the bearing retainer and the retainer itself had to be replaced to stop it from leaking....I'd probably try to find a good OMC shop and take it to em...

 

[Sugo]

Re: Omc Leg Gasket

I think thats what I am going to do, thanks