Cobra Pressure test results

[LAC_STS]

Ok so Ive been having water in my drive oil. I took the drive off to fix this and do the other maint items like the bellows.

I put 15 PSI in the drive and I can hear it leaking out around the propshaft. So, I got a bottle of soapy water and started spraying. I cant find any leaks anywhere except the propshaft.

Its not the seal that you can see on the prop shaft, its farther back. I have attached a pic but its hard to get a shot in there.

You can see the bolts inside the housing. Its coming from one of the bolt areas, top left in the pic.


So what seal is this that is leaking? And how hard is it to fix? Am I going to need special tools or to reshim anything?


Much Thanks

 

[LAC_STS]

Re: Cobra Pressure test results

Well I called around and tried to get some guesstamites on how much to fix this if I dont do it myself.

Im now more confused. I called 4 or 5 places and got everything from one guy saying it just needs re sealed ($200 labor plus parts)said hes done tons that were the exact problem/spot as mine, to one guy saying that almost every cobra he has fixed that was leaking from where I told him the bearing carrier needed to be replaced.

Then one guy told me the whole lower unit needs a rebuild.


So which one is it? I know these guys didnt see the drive but statements of done tons it just needs a re seal, or done tons and it needs replaced or rebuilt makes me think.


I dunno, I might do it myself. Ive been looking at the manual but need some input from someone whos done it.

 

[Don S]

Re: Cobra Pressure test results

No one can give you a quote over the phone if they don't know what is leaking or where. Even if they could see the bubbles, they couldn't tell you what it would cost because they have no idea if just a seal is bad, or the shaft is bad, or housing is cracked or "___Fill in the blank___".
It may very well be the oring for the carrier, or a leak between the upper and lower. Hard to say.
Do you have the OEM service manual?
Are you mechanically inclined?
Do you have the special tools for the job?

 

[LAC_STS]

Re: Cobra Pressure test results

Thanks Don. I just told them it wasnt leaking from where the actual prop shaft enters the housing kinda like the seal on a hydraulic ram where it goes into the cylinder. Its not that seal its the bolts behind the prop shaft.

The only thing Im concerned about is which tools I absolutely need and which ones I can improvise. I have no problems buying the tools I need, which is kinda why I was asking. If I need more tools than its gonna cost to pay someone to fix it then I might pay to have it done.

I got a pretty good quote from one guy to reseal the entire lower unit. But is it true that when the prop shaft seals leak the bearing carrier usually needs replaced?

Im gonna separate the upper and lower units and pressure test the lower (I guess both actually) and see if it is still leaking.

 

[LAC_STS]

Re: Cobra Pressure test results

Well after researching all day I have come to the conclusion that I should take it somewhere. The cost of the tools is almost double or more what I can get it fixed for. Also I read that when used in salt water the bearing carrier can be a PITA to remove. Heat is needed. And then I read that the prop shaft has to be checked 1st to see if its bent. .003 or more and it will make the new seals leak quick. So cost of tools vs cost of repair vs having not done it before vs .....

I have another thought though. I might be able to get a SEI lower unit replacement for $845 or maybe I should look around first for a new or rebuilt lower unit. If the prop shaft is bent (which I am thinking it is because of how bad the leak is and also when I put a heavy SS prop on it it made the whole boat vibrate like crazy) the cost of re sealing it plus the prop shaft, plus maybe bearing carrier will be maybe more or close to what I can get a lower unit for.


I dunno but I thank you for the help Don and if you (or anyone else) have a suggestion which way I should go Im all ears.

 

[Don S]

Re: Cobra Pressure test results

SEI does not have lower units for Cobra drives, those $845 lower units are for outboards.

You really need to drain the gear lube and do a pressure check of the drive and determine where the leak really is before you go looking for new parts. The leak could be from above and leaking down an puddling in the lower unit. Read this thread before you give up on the pressure check. http://forums.iboats.com/showthread.php?p=1573303#post1573303

 

[LAC_STS]

Re: Cobra Pressure test results

I did drain the lube and pressure test it. When I said in post 4 I was saying Im gonna seperate the upper and lower units and just pressure test the lower to see if the leak was coming from inbetween the upper and lower.

When I pressure tested the while drive I sprayed soapy water all over the entire drive and the only place I saw a leak was behind the prop shaft in the lower unit housing.

 

[Joshua Nichols]

Re: Cobra Pressure test results

You are going to have to pull the bearing carrier out of there.. If you pick up a puller and decide to do it.. Make sure you have the drain plug out.. That will ruin ur day..
Is the leak coming from around the bolt head or between the carrier and the case?

Never had to heat the carrier or case to get one off, but I play in the lake world not the salt water...

 

[LAC_STS]

Re: Cobra Pressure test results

I think it's from the bolts (2 of em) back there. I'm workin on getting the upper and lower separated. One of the bolts doesn't wanna come so I gotta go get my torch set from my friend.

There's not a bunch of corrosion onthe drive but I'd imagine if I'm needing heat to separate the lower and upper the bearing carrier is gonna need it too.


But once I get theses separated I'm gonna pressure test just the lower and see.

 

[Joshua Nichols]

Re: Cobra Pressure test results

there are little seals on those bolts.. Might be where ur failure is coming from... Be careful with that torch

 

[LAC_STS]

Re: Cobra Pressure test results

I saw in the manual the bolts had sealant on them. I'm hopeful but I doubt it. I have to go to a machine shop to drop some heads of from another project. I might just see if theyll get the bolt out.

Once I get the lower off Ill pressure test the lower and see what I can see. If it looks like its the bolts Ill order new ones or re seal them.

 

[Joshua Nichols]

Re: Cobra Pressure test results

I would say replace all four of number 29

 

[LAC_STS]

Re: Cobra Pressure test results

Well I cant believe it myself but I replaced all four washers and screws that you recommended and now I pressure tested it again it has had 17 PSI in it for about 30 mins. I replaced them one at a time becuase I didnt know if I could just take all four out at the same time if I wasnt completely taking the carrier and stuff out. I also rotated the prop shaft to see if it would leak.

My manual says to put 16-18 PSI in it and that it shouldn't loose more than 1 PSI in 3 mins. So going by that I'm good. Of course I cant find my vacuum gauge but I'm gonna go get one tomorrow and do a vacuum test.

I still cant believe it. I usually dont luck out like that. I really hope it passes the vacuum test. Then I'll be painting it!



THANKS!!!

 

[Joshua Nichols]

Re: Cobra Pressure test results

Then I'll be painting it!

Seems like all the cobras I seen need paint..I painted mine last summer... Had it looking beautiful... Then I hung up on a sandbar.:facepalm:. Now looks like Freddy Kruger took his claw to the bottom... I used a coal metallic.. I know it's not a factory match but dang it looked good...Lots of coats and lots of clear... I had nothing but time to paint it cause I was waiting on parts...

Glad it seems like you stopped your leak easy.. I had a 65hp johnny leak at the same place..